Zhores Alferov The History of Semiconductor Heterostructures Reserch: from Early Double Heterostructure Concept to Modern Quantum Dot Structures

St Petersburg Academic University — Nanotechnology Research and Education Centre RAS • Introduction • Transistor discovery • Discovery of laser-maser principle and birth of optoelectronics • Heterostructure early proposals • Double heterostructure concept: classical, quantum well and superlattice heterostructure. “God-made” and “Man-made” crystals • Heterostructure electronics • Quantum dot heterostructures and development of quantum dot lasers • Future trends in heterostructure technology • Summary 2 The Nobel Prize in Physics 1956 "for their researches on semiconductors and their discovery of the transistor effect"

William Bradford John Walter Houser Shockley Bardeen Brattain 1910–1989 1908–1991 1902–1987 3 4 5 6 W. Shockley and A. Ioffe. Prague. 1960. 7 The Nobel Prize in Physics 1964

"for fundamental work in the field of quantum electronics, which has led to the construction of oscillators and amplifiers based on the maser-laser principle"

Charles Hard Nicolay Aleksandr Townes Basov Prokhorov b. 1915 1922–2001 1916–2002 8 9 Proposals of semiconductor injection lasers

• N. Basov, O. Krochin and Yu. Popov (Lebedev Institute, USSR Academy of Sciences, Moscow) JETP, 40, 1879 (1961) • M.G.A. Bernard and G. Duraffourg (Centre National d’Etudes des Telecommunications, Issy-les-Moulineaux, Seine) Physica Status Solidi, 1, 699 (1961)

10 Lasers and LEDs on p–n junctions • January 1962: observations of superlumenscences in GaAs p-n junctions (Ioffe Institute, USSR). • Sept.-Dec. 1962: laser action in GaAs and GaAsP p-n junctions (General Electric , IBM (USA); Lebedev Institute (USSR). y n s i t t e i n h t i g L Wavelength

“+” n EF n p LD p LD GaAs Eg hν n p EF Cleaved mirror “–”

n p Condition of optical gain: E F – E F > Eg 11 The Nobel Prize in Physics 2000 "for basic work on information and communication technology"

“for developing semiconductor “for his part in the heterostructures used in high-speed- and invention of the opto-electronics” integrated circuit”

Zhores I. Herbert Jack S. Alferov Kroemer Kilby b. 1930 b. 1928 1923–2005 12 13 circuit

14 15 16 Fundamental physical phenomena in classical heterostructures

(a) Ec Electrons ∆Ec One-side Injection Fn Propozal — 1948 (W. Shokley) Experiment — 1965 (Zh. Alferov et al.) Fp

Holes ∆Ev

(b) Electrons Superinjection F n Ec Theory — 1966 (Zh. Alferov et al.) Experiment — 1968 (Zh. Alferov et al.) Fp Ev Holes

(c) Diffusion in built-in Electrons quasielectric field Theory — 1956 (H. Kroemer) Experiment — 1967 (Zh. Alferov et al.)

17 Fundamental physical phenomena in classical heterostructures

(d) Electron and optical confinement Ec Propozal — 1963 (Zh. Alferov, R. Kazarinov) Fn (H. Kroemer)

Fp Experiment — 1968 (Zh. Alferov et al.) Ev

(e) Ec Superlattices Theory — 1962 (L.V. Keldysh) Experiment —1970 (L. Esaki et al.)

Ev Stimulated emission: Theory — 1971 (R. Kazarinov and R. Suris) Experiment —1994 (F. Capasso et al.)

18 Heterojunctions—a new kind of semiconductor materials: Long journey from infinite interface recombination to ideal heterojunction

2.8 Lattice matched ] AlP heterojunctions K

0 • Ge–GaAs–1959 0

3 2.0 GaP (R. L. Anderson) [

) AlSb

V • AlGaAs–1967 e InP ( (Zh. Alferov et al.,

p GaAs a 1.2 J. M. Woodall & GaSb y g H. S. Rupprecht) g r Ge • Quaternary HS e n 0.4 InAs (InGaAsP & AlGaAsSb) E 5.40 5.56 5.72 5.88 6.04 6.20 Proposal–1970 Lattice constant (Å ) [300 K] (Zh. Alferov et al.) First experiment–1972 (Antipas et al.) 19 Radiation spectrum for the first low threshold AlxGa1–xAs DHS laser at room temperature (a) (3) 1.59 eV 1.39 eV

) 300 K 2 t s i Jth = 4300 A/cm n ×100 . u b r (b) a (2) 1.59 eV (2) ( t y

i 1.61 eV s n t e n i n o t i a i (1) 1.61 eV (1) d a R

7100 7700 8300 8900 7760 7820 Wavelength (Å ) Wavelength (Å ) 20 Schematic representation of the DHS injection laser in the first CW-operation at room temperature

200 mA m µ Metal 0 2

SiO2 1 p+ GaAs 3 µm p Al0.25 Ga 0.75 As 3 µm p GaAs 0.5 µm p Al0.25 Ga 0.75 As 3 µm n GaAs Metal 250 µm Copper

21 Heterostructure solar cells

Space station “Mir” equipped with heterostructure solar cells

22 Heterostructure microelectronics Heterojunction Bipolar Transistor

∆Ec Suggestion—1948 (W.Shockley) Ec Theory—1957 (H.Kroemer) F ∆Ev Experiment—1972 (Zh.Alferov et al.) Ev AlGaAs HBT

HEMT—1980 (T.Mimura et al.) ∆E c E1 Ec 10 ns F E0 y

e l a 1 ns ∆Ev Ev t i o n d NAlGaAs-n GaAs Heterojunction g a

o p a 100 ps r P

J–J 10 ps

100 nW 1 µW 10 µW 100 µW 1 mW 10 mW Power dissipation

Speed-power performances 23 Heterostructure Tree Advanced LAN (by I. Hayashi, 1985) Bidirectional Wide Band Video Network Optical Transition Super High Speed Wavelength Division Computer Multiplexity Monolithic One Chip OEIC Repeater Switch Optical All Optical Link Multi- Connection Between Wavelength PIN-FET LSIs Phased LD LD-Driver MSI Optical One Chip Laser Disk Wiring Computer Array SSI Laser Printer LD Integration Inside of Optical LSI LSI and Electronic Detector Devices Optical Sensor Array Integration Integration of HEMT of Optical HBT HS Bifunctional Solar Devices Devices High APD FET GaAs Cell's Power LD PIN IC Electronics Integration LED Technology

Device Technology

Substrate Epitaxi Process Material Crystal Thin Film Technology Characterization 24 Impact of dimensionality on density of states

P

N 3D

Egap Energy Lz

P

N 2D t a e s

E0 E1 o f s Lz t y i

P Lx

1D D e n s N

E00 E01

Lz Lx P Ly N 0D

E000 E001 25 Temperature dependence of the normalized threshold current for different DHS lasers

1.5  — JTth()  T  t h J =   — th = exp  Jth(0) T0 n t J r e u (d)

c 1.0 d l (c) h o

s (b) r e (a) T0 = 104 °C

d t h (a) (a) Bulk

e (b) T0 = 285 °C z i l (c) T = 481 °C

a 0 (b) Quantum well (d) T0 = ∞ o r m (c) Quantum wire N

0.5 (d) Quantum dot –60 –40 –20 0 20 40 60 Temperature (°C) 26 Stranski–Krastanow growth mode

• High surface energy of the substrate — thin wetting layer • High surface energy of the film — 2D growth • High strain energy of the film — 3D Clusters

Frank–van der Merve Volmer–Weber Stranski–Krastanow

27 001

100

2 nm

Cross-section of high resolution electron micrograph image of a single quantum dot for 3-ML InAs deposited; arrows indicate the boundary facets. 28 Cross-section TEM image of MBE-grown laser with InGaAs-AlGaAs QDs 20 nm 2 nm Al0.3 Ga 0.7 As–1 nm GaAs ×50 SL Al0.15 Ga 0.85 As matrix

Ts = 480°C

Vertically coupled quantum dots

2 nm Al0.3 Ga 0.7 As–1 nm GaAs InGaAs ×47 SL Cladding layers are grown at 700 °C High power operation up to 1W CW 29 Vertical-Cavity Surface-Emitting Lasers

Edge Emitting Laser

Vertical Cavity Surface Emitting Laser (VCSEL) VCSELs: • Ultralow threshold current • High beam quality • Monolitically-integrated mirrors Planar technology, on-wafer testing, dense arrays, on-chip integration 140% annual market growth. Need in reliable 1.3 & 1.55 µm VCSELs, in UV VCSELs

30 Quantum cascade lasers Band diagram Layer sequence

Emission spectrum at room Light- and Volt-current temperature characteristics 1 12 80 ) .

u Pulsed 8K .

a room temperature , . 0.1 60

o g 8 V 150K

, ( l m W r , g e r e 40 a 0.01 e t l w o

V 200K p o w 4 P o 0.001 20 c a l i t

p 250K O 0 0 8.5 8.6 8.7 0 0.5 1.0 1.5 Wavelength, µm Current, A 31 Milestones of semiconductor lasers

105

4.3 kA/cm2 104 (1968) Impact of Double Heterostructures

) 2 103 Impact of

m

c 2 / 900 A/cm Quantum Wells

A

(

(1970) 2

h 40 A/cm t 2 Impact of

J 10 160 A/cm2 (1988) Quantum (1981) Dots 19 A/cm2 10 (2000) Impact of SPSL QW 6 A/cm2 (2002) 0 1960 65 70 75 80 85 90 95 00 2005 Years • Evolution and revolutionary changes Reduction of dimensionality results in improvements • 32 “Magic Leather” energy consumption Total throughout the world Reserves Energy Carrier (known and Consumption Period of extractive) rate exhaust (GWatt × year) (GWatt) (years) Oil 200 000 4 600 40–50 Gas 150 000 2 200 60–70 Coal 1 000 000 3 000 300–400 Nuclear Power 90 000 750* 120 (thermal reactors) Total 1 440 000 11 000 130 Nuclear Power 15 000 000 11 000* 1 500 (fast reactors) *Calculated value 33 The evolution of achieved in the world till 2006 and predicted efficiencies of solar cells based on III-V semiconductors

50

n

o i 45

s

r

e

v 40 n III-V Concentrator

o

c

Multi-junction

y 35

g r Concentr. e Concentrator n 30 AlGaAs/GaAs Si

e

r Single-

a l 25

o junction

s

f

o 20

) Cryst. Si

% “one-sun” ( 15

y

c

n 10 Thin-Film

e

i

c Si

i

f f 5

E

1950 1960 1970 1980 1990 2000 2010 2020 Year 34 Concentrator PV installations at the Ioffe Institute

Mirrors, large cells, heat pipes Fresnel lenses, medium Smooth lenses, small (early 1980s) cells (middle of 1980s) cells (late 1980s) The tendency in concentrator PV: from large to small concentrators at high concentration ratio!

35 Multijunction solar cells provide conversion of the solar spectrum with higher efficiency. Achievable efficiency of multijunction cells is > 50%

Ge

Si GaInP GaAs 1600 1600

e 1400 1400

c

n

) 1200 1200 a

i

m d 1000 1000

µ

a

r

r

2

i

800 800

l

m

/

a

r 600 600

t

W

c

(

e 400 400

p

S 200 200 0 0 500 1000 1500 2000 2500 500 1000 1500 2000 2500 Wavelength (nm) Wavelength (nm)

36 The theoretical limit for MJ cells

75 46200 x 850 W/m² AM1,5d T = 333 K 70

) 65

%

(

y

c 60

n

e • Calculation made in i

c

i

f f 55

the radiative limit E

• Calculated for the 50 concentration limit 45 • Optimum band gaps 40 assumed 0 1 2 3 4 5 6 Number of pn-junctions

37 Evolution of the solar electrical capacities till 2030 year

140 USA Europe ) 120 Japan W

G World ( 100 e s i t 80

60

40

20 I n s t a l e d c p i

0 2000 2010 2020 Year 2030 38 Is Solar Energy Conversion an Option to Solve the Energy Problems in Future?

Yes! 39 White light-emitting diodes: efficiency, controllability, reliability, life time Today: Outlook: InGaN-QW/GaN/sapphire Monolithic microcavity LED with light-emitting chip + YAG Ce phosphor InGN/GN MQW active region

White White Phosphor YAG Ce

Sapphire Sapphire

Buffer Buffer

n+GaN n+GaN

InGaN-QW Ti/Ag/Au

p+GaN InGaN-QW p+GaN Bragg resonator Ni/Ag/Au Ti/Ag/Au GaN/AlGaN Ni/Ag/Au

+ simple design + monolithic nature – phosphor loss + absence of additional loss 40 Nanostructures for high power semiconductor lasers

Solid-state lasers pumping

Atmospheric and Fibre fibre optical lasers communication

Medical

m Navigation

n

5 nm

apparatus ,

s

s

e

n

k

c

i

h

T Band gap, eV Energy transport Atmospheric in the atmosphere lidars and fibre

Laser efficiency > 75% Welding and cutting Laser array output power > 100 W Laser power > 10 W Matrix output power > 5 kW 41 Summary 1. Heterostructures — a new kind of semiconductor materials: • expensive, complicated chemically & technologically but most efficient 2. Modern optoelectronics is based on heterostructure applications • DHS laser — key device of the modern optoelectronics • HS PD — the most efficient & high speed photo diode • OEIC — only solve problem of high information density of optical communication system 3. Future high speed microelectronics will mostly use heterostructures 4. High temperature, high speed power electronics — a new broad field of heterostructure applications 5. Heterostructures in solar energy conversion: the most expensive photocells and the cheapest solar electricity producer 6. In the 21st century heterostructures in electronics will reserve only 1% for homojunctions

42