CQD Atomic Engineering of III-V Semiconductors for optoelectronic Quantum Devices from; Deep UV(200nm) to THZ( 300 microns)

Manijeh Razeghi

Center for Quantum Devices Dept. of Electrical Engineering and Computer Science Northwestern University, Evanston, IL 60208

email: [email protected], Ph: (847) 491-7251, Fax: (847) 467-1817

Boston Chapter of IEEE Photonics Society: Emerging Optical Materials Workshop Wednesday, April 12, 2017 1 Major Achievements of 20th Century CQD

Physical Science Q-mechanics Atomic Structure

•Semiconductors •Superconductors •Simulation •Polymers •Interconnection

Natural Information Electronics Science Science Computer& Internet

•Artificial Neural •Simulation Networks •Interconnection •Fuzzy Logic

Life Science Genetics Gene & Cell Structure

2 Quantum Optoelectronic Devices and ResearchCQD optoelectronic devices will be involved in all areas of a human’s life, trying to improve the functionality of its body and mind. Examples of Quantum device applications are given below. EXPLORATION (Space & Underwater) needs reliable electronics in all these domains • Pollution sensors • Food safety • Solar Cells • ... • Energy efficient • Virtual reality • Bullet medicine devices (LEDs...) Food • ... • Sensors • Biomimetrics Energy Health • ... Medicine Needs of each individual in Society Entertainment Transportation • Virtual reality Communication • Computers • Electrical vehicles • Optical fiber (WDM, DWDM) • Video games • Computers • Wireless • Interactive media • Sensors • Personal Digital Assistant • Internet • ... • ... • ...

3 What Is a Semiconductor? CQD

conduction band

n-doping p-doping E band gap

valance band

IIA III-V isolated atoms crystal distance in real space

Be IIIA IVA VA VIA A B A C D E Mg B C N O

Ca IIB Al Si P S

Sr Zn Ga Ge As Se

Ba Cd In Sn Sb Te Ra Hg Tl Pb Bi Po band gap engineering 4 4 CZOCHRALSKI Bulk SC, Epitaxy & CQD Processing

Epitaxy

Bulk Semiconductor

Semiconductor lasers

Photo Lithography

5 Artificial Atoms and Molecules “Mimicking” Nature CQD Toward 0-D confinement Density of State 3D

Bulk Q-DOT

3D 

Material  DOS (3D) DOS • Artificial Atom such as Quantum

Eg 2D Dots are the basic building blocks of

the Artificial Molecules.

2D  Quantum  • Artificial Atoms enhance our

knowledge about the nano-structures DOS Well DOS (2D) due to their simple structures. E E E g 1 (c)2

(a) (b) 1D

1D 

Quantum  DOS Wire DOS (1D) Eg E11 E12 E13 (a) (b) (c) 0D • Information Technology can be revolutionized by Artificial Molecules:

0D Quantum  • Artificial Active material can be Dot DOS produced: (0D) •Nano-Sensors and nano-Machines Eg E111 E112 E113E211 •Smart Material (adjustable (c) viscosity, density, elasticity, ...) 6 (a) (b) 6 Quantum Sensing CQD Inspirations from nature The five basic Neurons for human senses Moving Information The Human Brain

Sight Hearing Signals from various Smell senses in the body are Basic functions of the brain: carried to the brain as • Signal Processing Taste • Cognition electrical pulses. Touch • Emotion • Judgment • Memory 7 Sense of Sight: CQD Electromagnetic Wave Detection

Cone Rod Ganglion cells

Axons to brain

The rods and cones contain photo-sensitive pigments. Light strikes the pigments and causes the pigment to release energy. This ultimately leads to the nerve firing and eventually the perception of light. Optic nerve

IEEE Spectrum May 96

8 Background: Human sense of sight and the EM spectrum CQD

• Human Vision is limited to a very narrow band of the spectrum (400–700 nm). • Humans must rely on technology to extend the limits further into the infrared and ultra-violet regions.

UV VIS NIR MWIR LWIR VLWIR 9 9 Our Goal: “Mimicking” Nature CQD

To processing unit

Interaction Nature inspires us Artificial sensors modify nature

To processing unit

10 10 #

CQD History: Razeghi’s Group in Paris (Thomson CSF-LCR) - Sep1980-1991 CQD

11 CQD

1.3 &1.5 mm Lasers for low Loss and Low Dispersion Silica Optical Fiber WDM

12 LP-MOCVD GaInAsP-InP BRS Laser Emitting at 1.3mm CQD

Light-current and voltage-current characteristics of BRS laser under CW operation at 20C.

M. Razeghi, The MOCVD Challenge Volume 1 (Philadelphia: Adam Hilger, 1989)

13 GaInAsP 1.3 mm Lasers on Silicon CQD

M. Razeghi, The MOCVD Challenge Volume 1 (Philadelphia: Adam Hilger, 1989) 14 CQD

15 Results of Photonocs for near IR CQD

!982-1992

M. Razeghi M. Razeghi M. Razeghi CRC press CRC press CRC press published 1989 published 1995 published 2010

16 Northwestern University CQD

• Founded 1851, by John Evans and others • Private University • Spread over 2 campuses: – Evanston (240 acre) – Chicago (25 acre)

17 CQD History: Bringing Razeghi from Thomson to Northwestern CQD

“It’s probably our biggest hire in 20 years,” said Cohen

18 19 CQD History: The Very Beginning of the CQD CQD

19 20 CQD’s First Open House: May 14th, 1992 CQD

20 SSE Curriculum General Overview CQD EECS / McCormick Engineering

202 Undergrad 223 Solid State Engineering Curriculum

250 Undergrad/ 381 Graduate 384 388 385 401 403 405

402 Materials, 409 Graduate Processing, 495 Physics

Electronic Optoelectronics Transport 21 Books CQD

M. Razeghi M. Razeghi M. Razeghi Springer Science Springer Science CRC press published 2009 published 2010 published 2010

22 Overview of CQD Approach and Research Facilities CQD

• 5 MOCVD reactors • Windows PC • 2 MBE reactors • Matlab • Mathematica • X-ray diffractometer • Finite element • SEM Material • House engineered software • AFM Growth • PL, FTPL, topo-PL • FTIR • Ellipsometer Material Device • Optical pumping Characterization Physics • Hall Modeling • DLTS Chemistry Material Science • Focal plane arrays Mechanical Engineering • Laser pointers • E-beam evaporator Electrical Engineering • Ion beam sputtering Processing • Thermal evaporator Device Bio Engineering Systems • ECR-RF dry etcher • RTA Fabrication • PECVD • Optical lithography Device • E-beam lithography Measurement • Lapper / polisher • Wire bonder • Laser diode bench • UV photodetector bench • Laser diode life testing • IR photodetector bench • Electrical benches (for I-V, C-V, C-f) 23 • Black body 23 Inauguration of the CQD June 6th, 1993: Ribbon Cutting CQD

Leo Esaki Manijeh Razeghi Klaus von Klitzing 24 Research at the Center for Quantum Devices CQD

<0.2 mm Wavelength >300 mm

UV VISIBLE I N F R A R E D THz

III-NITRIDES QCL QDIP-QDWIP TYPE-II SL InP & Nitride QCLs

AlSb AlSb GaSb GaSb GaSb GaSb

InAs InAs InAs

25 Research at the Center for Quantum Devices CQD

<0.2 mm Wavelength >300 mm

UV VISIBLE I N F R A R E D THz

III-NITRIDES QCL QDIP-QDWIP TYPE-II SL InP & Nitride QCLs

AlSb AlSb GaSb GaSb GaSb GaSb

InAs InAs InAs

26 Applications of UV Quantum Devices CQD Space UV Astronomy Situational (Various l) SUN Awareness

UV countermeasures (l < 280 nm)

Chemical/Biological agent detection (agent specific l) UV Flame detection and combustion monitoring (l < 340 nm)

Ozone layer

Bio-Florescence Imaging Power line monitoring (specific l) (l < 280 nm) 27 27 Overview of III-Nitrides Al2O3, SiC, Si substrates CQD

Bandgap Tunability of III-Nitrides and III-Nitride Material System Select Materials Properties AlN Wurtzite crystal structure with hexagonal 6 symmetry Direct bandgap in the entire tunability: 5 AlXGaYIn(1-X-Y)N (Ideal for optoelectronic devices)

Wide bandgap (Eg(AlN) = 6.2 eV, Eg(GaN) 4 ZnS MgSe = 3.4 eV, E (InN) ~ 0.7 eV) => Low ZnO g GaN intrinsic carrier density, low leakage, low dark current UV 3 ZnSe SiC ZnTe High thermal conductivity, High AlP CdS GaP breakdown voltage (Ideal for high- AlAs 2 CdSe frequency, high-power transistors) AlSb CdTe GaAs InP Strong piezoelectric effects (Lack of center IR of symmetry along c-axis – beneficial for 1 GaSb transistors)

Bandgap Energy (eV) InN Direct Bandgap Indirect Bandgap InAs InSb Very strong chemical bonds (Large 0 difference in electronegativity between group 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 III elements and nitrogen) Robust materials: high melting point, Lattice Constant (A) mechanically strong, resistant to radiation damage 28 III-NitridesMaterial Growth Growth via Metal Organic Vapor Deposition (MOCVD) CQD

• Growth method: Aixtron Horizontal flow, low-pressure MOCVD reactor • Group III sources: TMGa, TMIn, TMAl

• Group V sources: NH3

• Dopants: n-type SiH4 & p-type DcpMg • Conditions: Pressure ~10-250 mbar, Temperature up to 1350 °C

29 Operation principles of photodetectors and lasers CQD

p-Type - p-Type + n-Type -

n-Type +

Photodetector Laser / LED

A V 30 30 World’s First Demonstration of AlGaN Photodetectors: Covering A Broad Range of The UV Spectrum CQD

Ti/Au Thin Ni/Au -1 x=0 p-GaN:Mg (500 Å) 10 QE=1 p-Al0.36Ga0.64N (500Å) x=0.45 i-Al Ga N (2000Å) 0.36 0.64 10-2 x=0.30 n-Al0.45Ga0.55N (1000Å) x=0.70 x=0.18 Al Ga N:Si-In Ti/Al 0.5 0.5 -3 x=0.15 (600nm) Contact layer 10 AlN ~ 75nm x=0.05 Al0.85Ga0.15N/AlN -4 SL (30x100Å) 10 AlN (350nm) Responsivity (A/W) Responsivity -5 LT- AlN buffer 10 Sapphire (0001) -6 For Back-Illumination 10 200 300 400 500 600 Wavelength (nm)

The Center for Quantum Devices has demonstrated photodetectors with cut-off wavelengths ranging from 360 nm down to 227 nm.

D. Walker, …, M. Razeghi, Appl. Phys. Lett. 76(4), 4003 (1999). 31 World’s First 254, 265, 280, & 340 nm Biological and chemical Sensing

p- p-type Ti/Au Current blocking layer Thin Ni/Au 2nd barrier: p-GaN:Mg (500 Å) Al0.4Ga0.6N, 5nm CQD p-Al0.45Ga0.55N (50nm) Quantum well: Al Ga N, 5nm p-Al0.6Ga0.4N:Mg (100 Å) CBL 0.36 0.64 Active layer (asymmetric SQW) 1st barrier:

n-Al0.45Ga0.55N (100nm) Al0.4Ga0.6N(:Si), 10nm Ti/Al Al0.5Ga0.5N:Si:In n-type cladding layer (600nm) Contact layer UV Emitters AlN 50nm

Al0.85Ga0.15N/AlN SL (30x100Å)

AlN (350nm) LT- AlN buffer Sapphire (0001)

254 nm 265 nm 280 nm 340 nm

EL Intensity (a.u.)

EL Intensity (a.u.) Intensity EL

EL Intensity (a.u.) EL Intensity (a.u.)

200 250 300 350 400 450 200 250 300 350 400 450 250 300 350 400 450 500 300 400 500 Wavelength (nm) Wavelength (nm) Wavelength (nm) Wavelength (nm)

340 nm 470 nm 257.5 nm 278 nm 279.5 nm 356 nm Tyrosine Tryptophan

A A F F

Normalized Intensity (a.u.) Normalized Intensity (a.u.)

250 300 350 400 450 500 550 250 300 350 400 450 500 550 Wavelength (nm) Wavelength (nm) A. Yasan, …, M. Razeghi, Appl. Phys. Lett. 83, 4701 (2003). A. Yasan, …, M. Razeghi, Appl. Phys. Lett. 81, 801 (2002). K. Mayes, …, M. Razeghi, Appl. Phys. Lett. 84, 1046 (2004). A. Yasan, …, M. Razeghi, Appl. Phys. Lett. 83, 4083 (2003). A. Yasan, …, M. Razeghi, Appl. Phys. Lett. 81, 2151 (2002).32 First Demonstration of Blue Lasers at CQD/NU New Year’s Eve – 10:00 PM CQD

33 CQD

34 Focal Plane Arrays: FPA Fabrication is a Multi-Step Process CQD

Indigo 320×256 ROIC FPA layout (Read Out Integrated Circuit) Fabrication process There are well over 50 Five FPA photomasks Four main phases: 30 µm pitch individual steps No.1 Pixel definition 1. Pixel definition involved in FPA No.2 Metallization 2. Metallization or passivation processing ! No.3 Passivation window 3. Indium bump fabrication No.4 FPA indium bump 4. Hybridization (flip chip No.5 ROIC indium bump bonding)

Semiconductor material grown Array pixel by ECR or Metallization for ohmic In bump evaporation and reflow MOCVD or MBE ICP dry etching contact on the detector on detector arrays and ROIC

ROIC ROIC

QDIPFPA QDIPFPA

Flip chip bonding Test for imaging Packaging on a leadless Substrate removal chip carrier after underfilling 35 Indium Bumps for FPAs CQD

36 World’s First AlGaN-based Solar-Blind UV Imaging SensorCQD

UV Detector Structure Ti/Au Thin Ni/Au Spectral Response 50 Un-Biased UV (280 nm) Image 40 External Q.E. 43% @ 278 nm Ti/Al Al0.5 Ga0.5 N:Si-In 30 (600nm) Contact layer

20

10 AlN (350nm)

Sapphire (0001) Efficiency Quantum External 0 200 225 250 275 300 325 350 375 400 425 450 For Back- Illumination Wavelength

Reflective Imaging Geometry Visible Image

• Reflective image of an Aluminum mirror pattered with an image of Professor Razeghi. • Inset in upper-left shows the band-pass spectral response of the back illuminated hetero-junction device. 37 R. McClintock, M. Razeghi et. Al Applied Physics Letters, 86(1), 011117 (2005) 37 World first Structural properties of LED epilayers CQD SEM & AFM measurements/on Si substrate

• To fabricate the SP-enhanced UV LED, 340 nm LED epilayer was grown on LEO AlN/Si(111) template with dimension of 2 µm trench and 2 µm ridge (4 µm period).

Coalesced LEO AlN on patterned AlN/Si(111)

RMS = 0.234nm

10µm × 10µm RRMS=1.07 Å

LEO AlN Ridge

Si (111) substrate Trench RRMS=1.34 Å

R. McClintock, M. Razeghi et al., Applied Physics Letters 102, 211110 (2013) R. McClintock, M. Razeghi et al., Applied Physics Letters 103, 191108 (2013) 38 Structural properties of UV LED CQD World first demonstration(SEM measurement) LED structure grown on LEO AlN/nano-patterned Si(111)

LED structure 3.5 um LEO AlN [111]Si

[1-10]Si Si (111)

• 340 nm LED full structure was grown on the optimized 2 um-thick LEO AlN/Si. • In order to improve the electrical properties of LEDs, the thickness of n-AlGaN was increased. • Total thickness of LED epilayer was 3.5 um.

R. McClintock, M. Razeghi et al., Applied Physics Letters 102, 211110 (2013) R. McClintock, M. Razeghi et al., Applied Physics Letters 103, 19110839 (2013) 39 History of III-Nitride Research at CQD Timeline of world first selected accomplishments CQD

Year Accomplishments References Ultraviolet Detectors st 1993 1 extensive study of choice of substrates for the MOCVD growth of GaN APL 63, 973 (1993). 105 Gain 1st crystallographic modeling of III-Nitride growth JAP 75, 3964 (1994). 1994 st 4 ~ 53,000 1 high quality AlN APL 64, 339 (1994). 10 st 1 high quality AlxGa1-xN APL 67, 1745 (1995). 1995 3 530 1st p-n junction GaN photovoltaic detector APL 67, 2028 (1995). 10 st 2 1996 1 MOCVD growth of GaN on LiGaO2 and LiAlO2 APL 69, 2116 (1996). 10 Gain ~ 100 1997 1st and only demonstration of entire range of Al Ga N photoconductors APL 70, 949 (1997). x 1-x 1 st 1 Lateral Epitaxial Overgrowth of GaN on Silicon APL 74, 570 (1999). 10 st

1999 1 visible blind AlxGa1-xN photodiodes APL 74, 1171 (1999). 0 Gain (log. scale) st 1 use of superlattices for enhanced p-type doping in AlGaN APL 74, 2023 (1999). 10 Avalanche Gain st -1 2000 1 and shortest wavelength AlxGa1-xN photodiodes (227 nm) APL 76, 403 (2000). 10 1st 280 nm UV LED APL 81, 801 (2002). 0 -20 -40 -60 -80 -100 2002 Bias Voltage (V) 2003 1st 265 nm UV LED APL 83, 4701 (2003). 2004 1st back-illuminated solar blind AlGaN photodiode with external QE  68 % at 0V APL 84, 1248 (2004). Visible LEDs 1st solar blind AlGaN FPA realized entirely within a University APL 86, 011117 (2005). 2005 1st back-illuminated solar blind AlGaN avalanche photodiodes APL 87, 241123 (2005). 1st back-illuminated linear mode GaN avalanche photodiodes APL 90, 141112 (2007). 2007 1st back-illuminated Geiger mode GaN avalanche photodiodes APL 91, 041104 (2007). 1st back-illuminated Separate Absorption & Multiplication GaN APD APL 92, 101120 (2008). 1st back-illuminated APD with -doped p-GaN APL 93, 211107 (2008). 2008 1st hybrid green LED with ZnO/InGaN/GaN hybridization APL 93, 081111 (2008). Intersubband Devices 1st inherently high quantum efficiency ultraviolet APDs APL 93, 211107 (2008). st 6 15 1 GaN nanostructured ultraviolet photodiodes APL 93, 221104 (2008). Mid-IR Negative

1st MOCVD-grown AlN/GaN superlattices with intersubband absorption at 1.5µm m) 5 APL 94, 121902 (2009). m differential st 10 2009 1 MOCVD-grown AlN/GaN SLs with intersubband absorption at 1.1µm APL 95, 201906 (2009). 4 resistance

1st MOCVD-grown AlGaN/GaN SLs with intersubband absorption at 5.3µm APL 95, 131109 (2009). Absorption Peak

st 3 1 MOCVD-grown AlN/GaN resonant tunneling diodes APL 96, 042103 (2010). 5 1st nonpolar ultraviolet avalanche photodiodes APL 96, 201908 (2010). 2 Near-IR

2010 |Current| (mA) at room Highest filter-free ultraviolet single photon detectors APL 96, 261107 (2010).

Wavelength ( 1 temperature 1st reliable and reproducible negative resistance in GaN resonant tunneling diodes APL (submitted - 2010). 0 1 2 3 4 5 6 7 -2 0 2 4 6 GaN Well Width (nm) Voltage (V) 40 40 CQD World First LP-MOCVD of Al Free 808-980 nm lasers , for Silica Optical Fiber WDM Applications Using; Si, GaAs & InP Substrates

41 World first LP-MOCVD Results of Photonocs for InP Developed by RAZEGHI CQD 1982-1992 (at Thomson-France)

M. Razeghi CRC press published 2010 M. Razeghi CRC press published 2010 42 World first High Power Aluminum-free InGaAsP/GaAs CQD UnCoated Laser Diodes

10 InGaAsP/GaAs Pulse 1.31.41.51.61.71.81.9 (l= 808 nm) Eg (eV) h = 1.3 W/A 8 d Uncoated facets GaAs:Zn W=100mm Schottky Gold TiPt/Au L=780mm CW Ga0.51In0.49P:Zn 6

GaInAsP W 4

Ga0.51In0.49P:Si Growth direction

AuGe/Ni/Au

2 Substrate Output Power (W/2 facets)

0 0 1 2 3 4 5 6 7 8 9 10 Current (A) Light-current characteristics of InGaAsP/GaAs (l=808nm) laser diodes in pulse and CW operations with aperture 100 µm.

M. Razeghi et al., Applied Physics Letters 66 (June 1995): 3087-3089

43

High-power laser diodes based on InGaAsP alloys

n

i

a G Manijeh Razeghi Center for Quantum Devices, Department of Electrical Engineering and CQD Computer Science, Northwestern University. Nature, Vol 369 (23), pp 631-633, 1994.

44 World first Life-time test of Al-free CQD InGaAsP/GaAs lasers (l= 808 nm)

3.0

2.5 1000 mW

1000 mW 60 °C 2.0 50 °C

1.5 1000 mW 500 mW 25 °C 1.0 60 °C

Current (normalized) Current 500 mW 0.5 25 °C

0.0 0 5000 10000 15000 20000 25000 30000 Aging time (hrs) M. Razeghi et al., Applied PhysDeic Letters 71 (Nov. 1997): 3042-3044

45 Research at the Center for Quantum Devices CQD

<0.2 mm Wavelength >300 mm

UV VISIBLE I N F R A R E D THz

III-NITRIDES QCL QDIP-QDWIP TYPE-II SL InP & Nitride QCLs

AlSb AlSb GaSb GaSb GaSb GaSb

InAs InAs InAs

46 Mid- and Far-infrared Laser Applications (Primarily 3- 300 micron wavelengths) CQD

Remote Chemical Sensing / Spectroscopy Laser Infrared Standoff Detection Countermeasures Pollution Abatement Monitoring

Free-Space Communications Chemical Lewisite, Nitrogen Mustard (H-N3), Sulfur mustard (HD), 4-Dithiane, Warfare Agents Diisopropyl methylphosphonate (DIMP), Dimethyl methylphosphonate (DMMP), Isoamyl alcohol, Methylphosphonic difluoride (DIFLUOR), w/ background w/o background Cyclosarin (GF), Sarin (GB), Soman (GD), Tabun (GA), VX, Triethyl phosphate, 2-diisopropylaminoethanol (DIPAE)

Toxic Ammonia, Arsine, Boron trichloride, Ethylene oxide, Nitric acid Industrial Chemicals Active IR Imaging / LIDAR

Surgery

47 Laser Background: Interband vs. Intersubband Lasers CQD

Intersubband Laser Typical Interband Laser (Quantum Cascade Laser) Conduction Conduction band band Electron Hole Photon Current Barrier Valence band Well

Interband lasers emit light through Intersubband lasers emit light from electron recombination of electrons with holes across transitions within the conduction band the bandgap of a semiconductor. The emission wavelength is determined by The wavelength is determined and limited the thickness and composition of the by the bandgap of the material individual layers

48 Principle of quantum cascade laser CQD

electron

 Intersubband transition  Unipolar device  Cascading emission

49 CQD

3-5mm Lasers for Fluoride Based Fiber WDM Applications

Interband, using

In As, GaSb, GaAs, Si Substrates

50 World first LP-MOCVD of InAsSb based Lasers: CQD Strain-Layer Superlattice developed by RAZEGHI Maximum emitting wavelength vs. year Presently, we have displayed record 5.0 Output Power

4.5 Threshold Current Density Series Resistance 4.0

But, at low temperature operation. 3.5

3.0

1996 1998 2000 • Reducing leakage current • Suppressing Auger recombination New superlattice technology developed By RAZEGHI

52 CQD World first GasMBE growth Of GaInAs/ InAlAs/InP

For 3-300mm Lasers Intersuband QCL

using

In As, GaSb, GaAs, Si Substrates

53 Infrared Quantum Cascade Lasers: History & Development CQD

Strain balanced Free-space MM waveguide RT-CW >50% WPE CW operation QCL QCL communications RP THz QCL l~10.2mm LT-Pulsed first demonstrated above LN Phonic crystal (CQD) (CQD) Light RT pulsed Photoacoustic amplification First 2DEG in spectroscopy QCL RT-cw RT-CW >20% WPE InGaAs on InP operation (intersubband) RT CW QCL BR-QCL l~3.8mm watt level RT-CW (Razeghi) Surf. Plas. first postulated DFB-QCL (CQD) (CQD) (CQD) (CQD) waveguide THz QCL

1970 1982 1994 1996 1998 2000 2002 2004 2006 2008 2010

1997 Center for Quantum Devices 2010

Highest RT CW PCDFB RT-CW Temp. l~8First QCL l~11mm DFB QCL 120 W 27% pulsed High mm QCLBar Test (1.5W)QCL QCLs 53% LT 21% CW Power Aging 5.1 W CW testing RT-CW First Single-Step BR-QCL 3.4 W & 16.5% Growth w/ GSMBE

54 Crystal growth MOCVD, Gas -MBE razeghi Based on InP / GaInAs / AlInAs Materials CQD

Low Pressure MOCVD Growth Gas-Source Molecular Beam Epitaxy

55 55 Quantum Cascade Laser A real QCL in different magnifications CQD

~ 1 cm

2 nm

56 CQD

57 High Power Continuous Wave Quantum Cascade Lasers CQD

10 T= 298 K • Maximum CW power Individual Diodes Continuous Operation 5 W at room temperature demonstrated

1 • The QCL is capable of >100 mW output power per diode at room temperature across a 0.1 wide spectral range

Results demonstrated by the • With further effort and the Center for Quantum Devices funding, range is Continuous (CW) Power (W) Northwestern University 0.01 expected to extend from 2 4 6 8 10 12 ~3-14 mm. Wavelength (mm)

58 Major Advances in Quantum Cascade Laser Research at the Center for Quantum Devices CQD 1997: First QCL growth by Gas-MBE. 1999: High temperature CW operation of l~8 mm QCL. 2001: High temperature (T>425 K) operation of l~11 mm QCL. 2003: First CW QCL (l~6 mm) at room temperature. 2005: First room temperature CW single mode QCL at l~4.8 mm. 2006: Development of room temperature CW QCLs from 3.8< l <11.5 mm. 2006: Word’s Longest wavelength (l= 11.5 mm) CW QCL at room temperature. 2008: Demonstration of Watt-level CW QCL at room temperature. 2009: Highest peak power QCL (120 W). 2010: Word’s Highest efficiency QCLs in the world (53% @ 40 K, 26% at 300 K). 2010: Word’s Highest peak power single mode QCL (34 W). 2011: Word’s Highest CW power single mode QCL (2.4 W). 2011: First demonstration of continuous wave surface-emitting ring laser. 2011: Word’s Highest power (5 W) and efficiency (21%) room temperature CW QCL. 2012: Word’s Shortest wavelength (l= 3 mm) CW QCL at room temperature. 2013: Word’s Widest electrical tuning (243 cm-1) for a single mode quantum cascade laser. 2014: Word’s Broadest gain bandwidth (4-12 mm wavelength range) with multi-core heterogeneous QCL. (unpublished) 2014: World’s First CW and highest peak power (1.9 mW) QCL-based THz sources at room temperature. (Appl. Phys. Lett. 104, 221105, 2014) 2014: Word’s Widest monolithically tunable THz sources (2.8-4.2 THz) at room temperature. (Appl. Phys. Lett. 105, 201102, 2014) 2015: World’s First monolithic solid state frequency comb (130 cm-1 span) at l~ 9 mm. (Appl. Phys. Lett. 106, 051105, 2015) 2015: Word’s Highest Power (1W) CW ring QCL with fundamental mode operation. (unpublished) 2015: Word’s Highest peak power (5W) single mode, widely tunable (140 cm-1) QCL. (unpublished) 2015: Word’s Highest Power (203 W) semiconductor laser with near diffraction-limited beam quality (unpublished)

Red = Still current world record 59 The World’s Highest Power QCL: Application of an Angled Cavity CQD 203 W

Angled cavity, broad area laser

W=300 mm

q=12o

 For this angled FP QCL, the tilt angle is 12. The ridge width is 300mm. The cavity length is 5.8 mm. The back facet is HR coated. The front facet is AR coated.  A room temperature output power of 203 W is obtained, which is the highest for any QCL. The wall plug efficiency is 10%.  The far field single lobed at the facet normal direction. The full width at half maximum angle of the far field is only 3, which is only twice of the diffraction limit (1.5).

D. Heydari, Y. Bai, N. Bandyopadhyay, S. Slivken, and M. Razeghi, in preparation (2015) 60 First Demonstration of On-Chip Beam Combiner CQD with Tunable QCL Array Broadband spectrum

Device Layout

• For directed energy applications, tunable emission should come from a single output. • An on-chip beam combiner, based on a tree array, is demonstrated. • This monolithic broadband laser source is highly attractive for spectroscopy, remote sensing, and security applications. Image of Device Die 61 Broadband spectroscopy sensing without moving parts World First demonstration

 The system weighs ~3kg and measures 127mm x 203mm x 184mm  All emission wavelengths are pre-calibrated and can be randomly recalled with a tuning speed up to 1kHz.  Using the laser system, we demonstrated the first broadband spectroscopic sensing without any moving parts. Tunable Laser System Project Evaluation CQD

63 Research at the Center for Quantum Devices CQD

<0.2 mm Wavelength >300 mm

UV VISIBLE I N F R A R E D THz

III-NITRIDES QCL QDIP-QDWIP TYPE-II SL InP & Nitride QCLs

AlSb AlSb GaSb GaSb GaSb GaSb

InAs InAs InAs

64 Nonlinear process in a QCL CQD

PEEEEEE(t)(t)(t)=(1)(2)(3) (t)(t) (t) (t)...

3 (2) e z12 z 23 zNNNN 313132  () ==12 2  021211313123232   iii  

(3) (2) 1,41,1==  1,2 4 2 N e z 1 0  ij  (i/ )(2i/   TTT )(222   i/ ) 3 3(i/0222 )(i/ )(i/  )  TTT   

 The principle of wavelength conversion is based on the nonlinear polarization of a dielectric medium.  In a QCL medium, such nonlinear properties is highly engineerable.  By optimizing the second order nonlinear susceptibility (2), THz light can be generated using difference frequency generation (DFB).  By optimizing the third order nonlinear susceptibility (3), a frequency comb can be formed through four-wave mixing.

65 World first Room Temperature THz DFG Paper and Press Release CQD

66 RT THz QCL sources from CQD CQD World’s highest THz power and wide frequency tuning

Composite DFB 2.0 L=3 mm, W=23mm (a) HR, epi-down, 293K 1.5 THz far field FWHM=12.5

1.0

0.5 -40 -30 -20 -10 0 10 20 30 x Angle (degree) 3.5 THz

THz peak power (mW) P =1.9 mW THz z 0.0 y -2 0 2 4 6 8 10 12 14 (b) (c) Current (A) M. Razeghi, Q. Y. Lu, et al., Proc. of SPIE 9199, 919902-1 (2014). Q. Y. Lu, M. Razeghi et al., Appl. Phys. Lett. 103, 011101 (2013)

 We demonstrate the world’s highest THz power from a room temperature monolithic device with 1.9 2 mW with an efficiency more than 0.8 mW/W . 10 mm 2 mm  The THz wall plug efficiency is 0.510-5, which is one order magnitude higher than previous (d) demonstration 0.1  The far field has a narrow beam divergence angle of 12.5. 0.0 4

4 -0.1 l l 67

1 2

-0.2 3 3 2 l Energy (eV) THz 1 2 -0.3 LO F=43 kV/cm 1 -0.4 40 50 60 70 80 90 100 110 120 Distance (nm) (a) (b) CW operation, 293 K Device 1 CW operation, 293 K Device 2

2.06 3.17 THz 3.20 4.35 THz

Intensity (a.u.) Intensity

Intensity (a.u.) Intensity Monolithic CW Tunable THz Source

1.5 2.0 with2.5 Epi3.0 -Down3.5 Mounting3.0 Scheme3.5 4.0 4.5 FrequencyWorld’s (THz) First Monolithic THz CWFrequency Tuning (THz) (c)

0.6 ) 4 Device 1 Device 2 2 0.5

W)

m 3 0.4

2 0.3

0.2 1 0.1

CW THzpower (

0 0.0 2.0 2.5 3.0 3.5 4.0 4.5 (mW/W efficiency Conversion Frequency (THz)

Q. Y. Lu, M. Razeghi, et al., Sci. Reports 6, 23595 (2016)

 In the tuned THz frequencies, the THz output power ranges from 0.6 mW at 2.06 THz to 4.2 mW at 3.42 THz. 2  The conversion efficiency peaks around 3.0-3.5 THz with hmax=0.36 mW/W at 3.2 THz, and decreases towards the lower and higher frequency ends.. CQD

Frequency comb characterization of a FP QCL at CW operation

69 Frequency comb CQD

5200

70 World first 9 microns Frequency comb CQD operation with high power output

CW operation, 20 C 100  The frequency comb I=1.84 A QCL device emits up 130 cm-1 to 223 mW at RT CW 10

with a spectral range of 130 cm-1 at l~9 mm. 1

Intensity (a.u.)  The measured 0.1 spectrum consists of 1080 1100 1120 1140 1160 1180 1200 evenly spaced 350 Wavenumber (cm-1)

modes with a constant 14 250 L=4 mm, W=12 mm -85 13.0 12 epi-down, CW operation intermode spacing 200 12.5 20 C 3 kHz -1 10 -90 12.0 around 0.38 cm (11.4 150 8 -95 11.5

GHz). 11.0 6 100 -100 10.5

Voltage (V)Voltage 4

Power (dBm) 50 -105 10.0

2 (mW) power Optical

 The corresponding (GHz) spacing Frequency 9.5 0 0 -110 9.0 0.0 0.5 1.0 1.5 2.0 -100-100 -75 -150 -50 -25 -100 0 25 -50 50 75 0 100 intermode beating Frequency 0 50 100 150 200 250 300 signal exhibits a Current (A) Frequency (kHz)+11.05 GHz Mode number linewidth as narrow as 3 kHz.

Q. Y. Lu, M. Razeghi, et al., APL., 106, 051105 (2015) 71 beatnote test for gs5431 device 2

-80 I=823.7 mA

-90 50.5 Hz

-100

-110 Intensity (dBm) Intensity -120

-130 11178.825 11178.830 11178.835 Frequency (MHz)

 A new temperature controller PTC10K-CH is installed for better temperature control. This controller can stabilize the temperature to 0.0012 C level.  With this controller a narrower beatnote spectrum is observed with FWHM of 50.5 Hz. High efficiency QCL Frequency comb Record-high power and efficiency QCL comb is demonstrated

100 QCL comb 11.1 GHz  World’s most powerful @ 293 K

QCL frequency comb was demonstrated by -1 using optimized quantum 10 and dispersion designs.  The device emits up to

Intensity (a.u.) Intensity -2 880 mW at RT CW with 10 the highest wall-plug efficiency of 6.5%. 1140 1160 1180 1200 1220 1240 1260 -1  The measured comb Wavenumber (cm ) Q. Y. Lu, M. Razeghi, et al., Nature Sci. Reports, 7, 43806 (2017)

spectrum spanning 110 1000 -60 12 938 -1 980 950 920 880 cm at l~8 mm consisting QCL frequency comb -65 838 CW operation 1030 805 10 800 1005 of evenly spaced 300 293 K -70 -75 1060 8 modes. 600

-80 1083

6 -85  The intermode beatnote 400 780 mA Voltage (V) Voltage -90

4 Power (dBm) signal exhibits a narrow -95 200 (mW) power Optical linewidth of 50 Hz in a 2 -100 -105 wide current range. 0 0 0.0 0.2 0.4 0.6 0.8 1.0 11.160 11.165 11.170 11.175 11.180 11.185 Current (A) Frequency (GHz) Moving Towards Application: QCL Reliability and Lifetesting CQD

Demonstrated Over 21,000 hours (>2.25 years)

of CW operation with Power >= 100mW 250 Cooling & thermopiles CF PF re-calibrated 200 (I decreased to 0.85 A) PF I increased to1.1 A + Electric Field: - PF QCL Sample A ~80 kV/cm PF PF 150 100 nm 100 mW PF PFPF starting

condition 100

QCL Sample B Power (mW) Two randomly selected l=4.6 mm QCLs 50 Room-Temperature (T=298K) CW Constant Current (I~0.85/~1.1A ) PF=Power Failure Rear Facets HR-Coated CF=Coolant Failure 0 2500 5000 7500 10000 12500 15000 17500 20000

Time (hrs) 350 14 QCL Sample B (1983A) 14 QCL Sample A (1983c) 300 L=3mm, W=11mm L=3mm, W=11mm 300 12 HR-Coated 12 HR-Coated 250 l=4.6 mm Aging l=4.6 mm Aging 250 10 T=298K Current 10 T=298K Current 200 (0.85A) (0.85A) 8 200 8

150

21,000 hrs 6 21,000 hrs 150 6 100 Aging Before Aging Voltage (V) 4 Voltage (V) Aging 100 Output Power (mW) Current 4 (Time = 0) Current Before Aging 50 (0.95A) Output Power (mW) (0.95A) 2 (Time = 0) 2 50 0 0 0 0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.0 0.2 0.4 0.6 0.8 1.0 Current (A) Initial Results published in: Current (A) A. Evans and M. Razeghi, Appl. Phys. Lett. 88, 261106 (2006) 74 World first High Temperature Lifetesting of QCL With power cycling By RAZEGHI CQD

Over 1 W at 100 °C

•Stress testing of high T0 1000 design, HR/AR coatings, 12 and epi-down bonding 800 •Testing at 100 °C 600 •Power cycling every 30

High T0 design 400 Voltage (V) Voltage HR/AR coated (mW) Power minutes 10 CW, epi-down on diamond T=100 oC w/ power cycling 200 I= 1.3 A •High power (1.1 W) after Cross section 0 800 hours 0 200 400 600 800 Duration (hrs)

Cavity dimensions: 5 mm x 10 mm Power at RT (@1.3 A) = 2.2 W

75 High Power Quantum Cascade Laser ‘Pointer’ CQD

76 World First Recent results at Center for Quantum Devices (Prof. Razeghi) CQD

Tunable QCL MOPA Broadband heterogeneous QCL High power, widely tunable QCL with integrated amplifier Pulsed with >5W over 113 cm-1. Gapless emission between 5.9-10.9µm from single wafer CW with >1.25W over 120 cm-1. Applications: Mid-infrared Applications: Mid-infrared spectroscopy, homeland spectroscopy, homeland security, security, industrial control industrial control

Applied Physics Letters 107,251101 (2015) Opt. Express 23, 21159 (2015) Terahertz& Frequency Comb Mid-Infrared beam combiner Room temperature, continuous wave, monolithic tunable Ultra-broadband, electrically tunable, compact Terahertz source based on mid-infrared quantum cascade monolithic, tunable, single aperture output mid-infrared laser (QCL) source Applications: Mid-infrared Applications: ThZ spectroscopy, homeland spectroscopy, airport security, industrial control security, medical imaging

Nature Scientific Reports 6, 23595, (2016) Nature Scientific Reports (2016) 77 Research at the Center for Quantum Devices CQD

<0.2 mm Wavelength >300 mm

UV VISIBLE I N F R A R E D THz

III-NITRIDES QCL QDIP-QDWIP TYPE-II SL InP & Nitride QCLs

AlSb AlSb GaSb GaSb GaSb GaSb

InAs InAs InAs

78 Applications of Infrared Photodetectors CQD

High operating temperature and multicolor FPAs are desirable

Automotive Weather Night vision Industry Forecasting

Electronics Infrared target Astronomy detection Industrial Space Medical Military (MWIR)&(LWIR) (MWIR)&(LWIR) (LWIR) (MWIR)&(LWIR)

79 79

s

r

o

t

c

e

t

e

D R R

CurrentI Infrared Detector Technologies CQDCQD Infrared Detectors

Intrinsic Bolometer Extrinsic Quantum Well QDIP/QDWIP

Type-I Type-II

HgCdTe Vanadium Silicon Blocked InSb dioxide impurity Band InGaAs QDs InAs/GaSb in InGaP QWIP Superlattices + High + High + Room + High + High + High + Less Pro Efficiency Efficiency Temperature Efficiency Uniformity Uniformity Temperature sensitivity + High Efficiency Con - Low - Fixed Cutoff - Low Speed - Very low - Low Developing - Low Efficiency Uniformity Temperature Efficiency Material

InGaP CB EF CB R CB Impurity Band InGaP IR light VB VB VB InGaAs 80 T 80 CQD QWIPs, QDIPs, and QDWIP

QWIPs – Quantum Well Infrared Photodetectors

QDIPs – Quantum Dot Infrared Photodetectors

QDWIPs – Quantum Dot-in-a-Well Infrared Photodetectors

Si, GaAs & InP substrates

81 81 Operation of QWIPs, QDIPs, & QDWIPs CQD QDIP QDWIP Barrier continuum states Barrier continuum states

Barrier Barrier

Excited States of QD Excited States of QW Barrier Possible IR excited transitions Possible IR excited transitions Incoming IR light Ground State of QD QD Incoming IR light Ground State of QD QD

QWIP and QDIP-QWDIP share similar operation principles: QWIP 1. Utilizes intersubband absorption for IR detection. Electrons in Emitter the quantum well or dots with the minimum energy are excited to a higher energy state after Collector absorbing the incident infrared photons. 2. Under the bias, excited - + electrons are collected to 5 10 15 20 25 Wavelength (mm) produce a photocurrent. 82 82 82 Quantum Dot Photodetectors: What Does a Quantum Dot Look Like? CQD

Self-assembled InAs QDs grown on GaInAs/InP matrix

Dot density= 2 x 1010 cm-2 Spherical dot with typical dot SEM image of the active region size of h=5nm and d=50nm of a 10 stacks InAs/GaInAs/InP QDIP.

83 83 83 World first QDWIP MWIR FPA Results: InAs/InGaAs/InAlAs/InP by RAZEGHI CQD

T=130°K T=200°K

25 periods of InAs/InGaAs/InAlAs/InP • Format: 320256 • Operating Temperature: 130K • Detection Wavelength l = 4.1µm • Frame rate: 32.64 Hz • Integration time: 30.41 ms • Applied bias: ~-3.5V Infrared imaging video • Mean NEDT: 340 mK • Working pixels: ~99% (QWIP) (Defined as NEDT < 2K) 84 84 Quantum Dot Photodetectors: Timeline of QWIP, QDIP, and QDWIP Technology CQD

QWIP First First First First demonstration of 640×512 First demonstration demonstration demonstration QWIP Hand- demonstration of 128×128 of Palm-size of two-color held camera of QWIP device QWIP array QWIP camera QWIP camera

1977 1987 1991 1994 1996 1998 1999 2000 2001 2002 2002 2006 MWIR First First First Idea of First demonstration of demonstration of First QWIP demonstration InGaAs/InAlAs intersubband demonstration of IR imaging based Hand-held QWIP array into of Al-free /InP QWIP absorption for 640×480 QWIP on linear QWIP camera space InGaAs/InP FPA array at IR detection camera array QWIP FPA CQD array at CQD

QDIP / QDWIP

Idea of QDIP device intersubband QDIP first proposed by demonstrat absorption for IR Rhyzii detection ed at CQD Stranski- High quality QDIP raster First ever QDIP First InP-based LWIR- High Krastanov III-V material scan imaging FPA array QDIP FPA QDIP FPA temperature growth mode self-assembled Demonstration demonstrated demonstrated at demonstrated demonstrated imaging QDIP discovered quantum dots of first QDIP demonstrated CQD at CQD at CQD FPA at CQD

1937 1977 1993 1996 1997 1998 2002 2003 2004 2006 2007

85 85 Low Dimensional Quantum Systems Physics of the Systems CQD

Low dimensions System Bulks or superlattices (Quantum wells, wires or dots)

Band structure

interband transition intersubband transition

Broad Band Narrow Band

Optical Spectra

• Spectroscopy • “Smart” systems Applications • General imaging / surveillance • Mine detection • Target detection • Target identification 86 CQD

Type-II InAs/GaSb Superlattices a developing material system For Third generation of IR Imaging

GaSb , InAs, GaAs, Si

Substrates

87 Type-II Photodetectors: InAs, GaSb, and the 6.1 Å Family CQD

3.0 Direct band AlP 2.5 Indirect band GaP AlAs Type II misaligned 2.0 AlSb 1.5 InP

(eV) Si GaAs

g

E 1.0 Ge GaSb 0.5 InAs InSb 0.0

5.2 5.4 5.6 5.8 6.0 6.2 6.4 6.6 Lattice Constant (Å) Comparison of the 6.1Å family with other semiconductors Band alignment of the 6.1Å family

• The 6.1Å family includes InAs (6.0583Å), GaSb (6.09593Å) and AlSb (6.1355Å), which are closely lattice-matched. 88 Optical Absorption in Type-II Superlattices CQD

(E2)

(E1) GaSb InAs GaSb Electron (E2)

Electron (E1) h Heavy-hole(HH1) Light-hole(LH1) EC k|| (HH1)

EV (LH1)

ESO

Real Space k-Space

89 89 ETBM-Red Shift from Decreasing GaSb Thickness CQD

Less Electron Interactions

More Electron Interactions M  Z

90 90 Type-II SL Modeling and Experimental Data for 12 mm Structure CQD

A Typical Mathematica Output with an Input of: m=13, n=7, y1=0, y2=0 Structural Optoelectric Behavior Behavior

100000 Lattice mismatch: ~400ppm Superlattice Peak GaSb buffer Peak FWHM~25 arcsec FWHM~16 arcsec

10000 (-1) (1)

1000

(-2) 66 A 66 A 100 (2) (-3) (3) Intensity ( a.u.) (-4) 66 A 66 A

10

26 28 30 32 Omega( degree) The energy band structure of the 12 μm sample

11

10 T = 77 K

)

/ W

1/2

cm.Hz

( D* 1010

The growth parameter of SLS for 3 4 5 6 7 8 9 10 11 12 13 14 15 the 12 μm sample Wavelength (mm) 91 91 Material Growth CQD

13 ML InAs/7 ML GaSb

100 A InAs-n+ 0.5 µm SL-n

3 µm SL-i

0.5 µm SL-p 1 µm GaSb p+

GaSb-p substrate

AFM HRXD AFMAFM HRXDXRD HR-XRDScan (FileName, C:HRD HR-XRDScan (FileName, C:HRD Superlattice peak 100000 GaSb buffer peak Superlattice peak 100000 GaSb buffer peak 10000 10000 Mismatch:+435ppm Mismatch:+435ppm 1000

66A 66A

1000

66A 66A

100 100 10 10 Solid-Source MBE 1 26 27 28 29 30 31 32 33 34 1 Modular Gen II 26 27 28 29 Omega30 (degree)31 32 33 34 Cracked As and Sb 1.5 Å RMS roughness High orderOmega diffraction (degree) Ga, In, Al, Be and Si Cells satellite peaks 92 92 World first Type-II FPAs on GaSb Substrates CQD MWIR & LWIR Movies

MWIR LWIR

93 World first Type-II FPAs on GaSb Substrates MWIR & LWIR Movies CQD

MWIR LWIR

94 World’s First 1k × 1k (MegaPixel) Type-II InAs/GaSb FPA l=11 mm & T= 81 K CQD

P. Manurkar, M. Razeghi, et. Al Applied Physics Letters 97(19), 193505 (2010). 95 Dual-band Infrared Detection Motivation

10000 Band 2 Hot Air Band 1 Space Ship (d) Background - In many cases, single-color imaging is 1000 limited by detector’s dynamic range

when the contrast is too high (Band 1). 100

Good imaging for one object leads to saturation (a) or under-exposure of others (b). 10 Spectral Radiance (a.u.) Band 1’

- In some cases, two objects emit the 1 same irradiance intensity (Band 1’), it Wavelength (a.u) is difficult to delineate the details if the imager looks at that spectral band (c (Fig c). a) b)

- A second detection band (Band 2) will solve the above issues, providing higher contrast and better details.

Raw image for illustration from http://science.ksc.nasa.gov/

96 n+ InAsSb capping layer (Si@1200°C) • The structures N-π-P n+ M-structure contact and P-π-N were grown M-barrier (Si@1080°C) World’s First (640×512) 2-color Red channel on top of each others. (Be@700-760°C) • Blue channel with π- active CQDregion (760°C) LWIR/LWIR Type-II SL FPA design aiming for 2 µm thickness 100% cut-off wavelength of 9.5 µm p+ SL ramped contact (760°C - 890°C) l=13 mm & 9.5 mm, T = 81 K was grown at the p+ SL ramped contact (760°C - 890°C) bottom.

Blue channel • Red channel with π- active region (760°C) 2 µm thickness design aiming for

13µm 100% cut-off (Be@700-760°C) A student is holding a 11.3µm narrow band filter wavelength was grown M-barrier (Si@1080°C) on top. n+ M-structure contact

• The total thickness of n+ InAsSb etch-stop layer (Si@1200°C) this structure was 8µm. n GaSb substrate Red Blue

100% 100% l Red=13mm l Blue=9.5mm E. Huang, M. Razeghi, et. Al OSA Optics Letters 36(13), 2560-2562 (2010). 97 World’s First (640×512) 2-color MWIR/LWIR Type-II SL FPA l=13 mm & 5.3 mm, T = 81 K CQD

Red Blue

100% 100% l Red=13mm l Blue=5.3mm

A student is holding a 11.3 µm narrow band filter

E. Huang, M. Razeghi, et. Al OSA Optics Letters 37(22), 4744-446 (2012). 98 Design for SWIR Type-II Photodiodes GaSb/AlSb/InAs(M-structure) as Absorption Material CQD

AlSb 9 3 mm

GaSb 8 -3000ppm

7 0ppm 2.5 Electron wavefunction 6

5 2

Hole wavefunction 4 Ego Eg1 3 3000ppm 1.5

Thickness of InAs (ML) 2

1 1 1 2 3 4 5 6 7 8 Thickness of AlSb (ML) X  Z InAs Calculated map of 50% cutoff k(Å-1) wavelengths for (InAs)n-GaSb- M-structure GaSb/AlSb/GaSb/InAs superlattice (AlSb)m- GaSb

• By inserting high band gap AlSb into GaSb layer, we are able to create high band gap material for the SWIR. • The AlSb will lift up the conduction band and lower the valence band at the same time, create high band gap material in SWIR regime and keep material in good mismatch with GaSb substrate. • InSb and GaAs interfaces are used. 99 World’s First 2-color SWIR/MWIR Type-II SL FPA l=2.2 mm & 4.5 mm, T = 81 K CQD

Red Blue Passive Imaging Active (Illuminated) Imaging

100% 100% l Red=4.5mm l Blue=2.2mm

E. Huang, M. Razeghi, et. Al OSA Optics Letters 38(21), 22-24 (2013). 100 Type-II Photodetectors: InAs/InAsSb CQD

3.0 Direct band AlP 2.5 Indirect band GaP AlAs 2.0 AlSb 1.5 InP

(eV) Si GaAs

g

E 1.0 Ge GaSb 0.5 InAs InSb 0.0

5.2 5.4 5.6 5.8 6.0 6.2 6.4 6.6 Lattice Constant (Å)

•InAs/InAs1-xSbx type-II superlattices consist of InAs and InAs1-xSbx which are not lattice-matched! It requires careful strain balancing.

•In absence of gallium in the new InAs/InAs1-xSbx type-II superlattices results in, it is expected that the number of defects to be reduced; therefore, the carrier lifetime increases, leading to higher QE, better dark current and noise.

101 3-color SWIR/MWIR/LWIR T2SL-based Photodetectors CQD Motivation

)

-1 SWIR MWIR LWIR VLWIR

m

m 1E22

-2

.cm 2500K -1 1E20 2227oC 1000K 827oC 1E18

photons.s ( 300K 27oC 1E16 230K -43oC 1E14

1E12 1 2 4 8 16

Spectral radiant exitance exitance radiant Spectral Wavelength(mm)

• MWIR and LWIR: Passive imaging: enhance thermal contrast, distinguish thermal objects from the environment. • SWIR: Active imaging: detailed, high contrast images and close to visible perspectives • Multiband detection: Object identification in a close-to-visible perspective rather than mere detection

102 102 3-color SWIR/MWIR/LWIR T2SL-based Photodetectors CQD Photodetector Design Concept

Bias Selectable Operation

Time Three channels can be operated sequentially by changing the amplitude of the applied bias

A. M. Hoang , A. Dehzangi, S. Adhikary, and M. Razeghi, “High performance bias-selectable three-color Short-wave/Mid-wave/Long-wave Infrared Photodetectors based on Type-II InAs/GaSb/AlSb superlattices,” Nature Scientific Reports 6, Article number: 24144 (2016) • The 3-color device has 1m active region for SWIR, 1.5 m active region for MWIR and 1.5 m active region for LWIR. • The SWIR and LWIR channels expected to operate to different polarity of bias, whereas MWIR is expected to operate in between.

103 103 3-color SWIR/MWIR/LWIR T2SL-based Photodetectors CQD Specific Detectivity, T = 77K

V =4.5V T = 77K b 13 V =1V 10 b V =-2V b

)

12

/ W 10

1/2

1011

cm.Hz

(

D* 1010

109 2 3 4 5 6 7 8 9 10 Wavelength (mm)

• The device operates as a SWIR, MWIR and LWIR photodetector at bias of -2, 1 and 4.5 V and provide a D* of 3.0×1013, 1.0×1011, 2.0×1010 Jones at peak responsivity (λ=1.7, 4.0 and 7.2 µm).

104 104 Development of GaSb/InSb Type-II SL Focal Plane Array Development CQD

2014 2013 2012 2011 2010 5 µm, 2008 CQD, 2007 NWU, 2006 2-4 µm, USA CQD, 2005 5-13 µm, NWU, 9-12 µm, USA CQD, IIFPAs Type 2004 12 µm, CQD, NWU, 2003 12 µm, 10 µm, CQD, NWU, USA 1989 CQD, CQD, NWU, USA 1987 9 µm, CQD, NWU, NWU, USA 1971 NWU, USA USA USA

5 µm, multicolor performance High CQD, 5 µm, IAF/AIM, NWU, Germany USA 8 µm, CQD, 2 color, NWU, USA IAF/AIM, Germany 105 World’s First Integrated Type-II SL HOT-MWIR Camera Integrated Dewar, cooler, electronics, battery, and display CQD

Camera System Integration

133 mm

78 mm

97 mm

G. Chen, M. Razeghi, et. Al Optics Letters 40(1), 29-32 (2015). 106 Research Scope(2016) Center for Quantum Devices (Prof. Razeghi) CQD Broadband Infrared detector Short Wavelength Infrared Detector Bias selectable 3 color Short-Mid-Long High-performance short-wavelength infrared photodiode Infrared detector based on based on InAs/InAs(1-x)Sbx/AlAs(1-x)Sbx type-II superlattices. InAs/GaSb/AlSb type-II superlattice Applications: Telecommunication, remote sensing, Applications: Border protection, astronomical observation missile defense, homeland security.

Nature Scientific Reports 6, 24144 (2016) Applied Physics Letters 107,141104(2015) Photo Transistor Quantum Dot in Well Infrared Detector Mid-wavelength infrared heterojunction phototransistor based Transfer of pixels to non-native Si substrate on type-II InAs/AlSb/GaSb superlattices on GaSb with gain D* of 6x1010cmHz1/2/W with 48% Applications: Telecomm, quantum efficiency at 150K remote sensing, astronomical observation Applications: Uncooled Infrared detection for military

Applied Physics Letters (accepted 2016) Manuscript under preparation Major Collaborators:

And Many Universities… 107 Summary CQD

<0.2 mm Wavelength >300 mm III-Nitride Summary

UV VISIBLE• The ICQD N F Played R A aR major E D role in the historical THz development of III-Nitrides—particularly III-NITRIDES AlGaNQCL. QDIP-QDWIP TYPE-II SL Nitride • We have demonstrated the World’s First UV QCLs photodetectors across the AlGaN compositional range. AlSb AlSb • We demonstrated the World’s FirstGaSb IIIGaSb - GaSb GaSb Nitrides based Solar-blind camera. • We demonstrated the World’s FirstInAs UVInAs LEDs InAs at strategic wavelengths for bio-agent sensing. • We demonstrated intersubband transitions from 1.3 to 5.4 µm. • We demonstrated the World’s First reliable II- Nitride resonant tunneling diodes for THz.

108 I N F R A R E D THz CQD

QCL QDIP-QDWIP TYPE-II SL InP QCLs QWIP/Quantum QDWIP/ Cascade QDIP Laser Summary Summary

• The CQD has playedtakenAlSb the pioneered AlSbQuantum the Cascade GaSb GaSb GaSb GaSb developmentLaser from an of idea InP to/InAs a practical/GaInAs tool/InAs thatbased is QWIPs,now transforming QDWIPs, industryand QDIPs. InAs InAs InAs • ByWe usingcurrently quantum hold mostdots weof thecan World’s take advantage ofRecords the quantized for highest density power, of states. shortest The resulting phononwavelength, bottleneck and longest leads wavelengthto long carrier (THz). • lifetimesUsing photonics and thus we high have gains. also demonstrated narrow spectral line-width and good beam- • We were the Word’s first to demonstrate focal shape… all while maintaining high power. plane array cameras based on these novel • quantumWe have alsodot devices. demonstrated wide-range continuous tuning from < 3 µm to > 10 µm • Using difference frequency generation (DFG) we have even demonstrated room-temperature terahertz lasers with powers > 1.9 mW.

109 The FutureI N F R A R E D CQD

TYPE-II SL Type-II Superlattice Summary

AlSb AlSb • The CQD has took Type-II superlattices from a GaSb GaSb GaSb GaSb novel idea to a material that is not revolutionizing military and commercial InAs InAs InAs infrared cameras. • We demonstrated the Word’s first Type-II camera in 2003. • We demonstrated the Word’s first 2-color Type-II camera in 2007. Since then we have demonstrated the Word’s first 2-color combinations from SWIR to MWIR to LWIR. • We demonstrated the Word’s first large- format Type-II camera in 2010. • We have also pinoered the development of novel architectures like pMp and gallium-free InAs/InAsSb superlattices.

110 I N F R A R E D CQD

QDIP-QDWIP TYPE-II SL TypeQWIP/-II QDWIP/Superlattice QDIP Summary Summary

• The CQD has tookplayedAlSb Type pioneeredAlSb-II superlattices the from a GaSb GaSb GaSb GaSb noveldevelopment idea to aof material InP/InAs that/GaInAs is not/ InAs based revolutionizingQWIPs, QDWIPs, military and QDIPs. and commercial InAs InAs InAs infrared cameras. • By using quantum dots we can take advantage • Weof the demonstrated quantized density the Word’s of states. first The Type resulting-II cameraphonon inbottleneck 2003. leads to long carrier • Welifetimes demonstrated and thus thehigh Word’s gains. first 2-color Type-II camera in 2007. Since then we have • We were the Word’s first to demonstrate focal demonstrated the Word’s first 2-color plane array cameras based on these novel combinations from SWIR to MWIR to LWIR. quantum dot devices. • We demonstrated the Word’s first large- format Type-II camera in 2010. • We have also pinoered the development of novel architectures like pMp and gallium-free InAs/InAsSb superlattices.

111 What does the Future hold? CQD • Our inspirations come from Nature. Fundamentally, Nature operates on the quantum level, and is full of wondrous uses of semiconductor Nanotechnology. • We have studied quantum wells, but, Nature is not limited to a single degree of confinement. Going forward we can go more quantum… go to quantum wires, to quantum wells, and ultimately to artificial atoms. This is not easy with current growth an processing techniques, but success here will lead to much smaller and more efficient devices. • We should also take a lesson from VLSI and silicon and go towards integration of optoelectronic components on a single wafer. By using silicon as a substrate we can also integrate these optical components directly with the silicon electronics that drive them. • Taking advantage of the above, we need to go towards more efficient devices—devices that operate at room temperature and that have maximal efficiency in converting electrons to photons, or vice versa. 112 Conclusions CQD • The Discovery of Electronic and Artificial light 130 years ago revolutionized human civilization perhaps more than any other discovery before it. • Today Thanks to semiconductor Quantum Optoelectronic devices light waves flashing along glass fiber or atmosphere is connecting up the global information systems into ever bigger networks.

• SC Quantum Devices act as a foundation for making of electronic and Optoelectronic system.

• So The question remains, could you imagine a world Without SC

113 CQD 20th Anniversery September 5th, 2012: Northwestern Solid-State Division CQD Members

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