Nanodevices for THz Applications Tomás González University of Salamanca, Spain Research Group on Semiconductor Devices THz Nanodevices at USAL Research Group on Semiconductor Devices - Modeling of nanodevices for THz applications - Design of optimized structures (feedback to technology) THz Laboratory - Detection and emission of THz radiation from plasma wave nanodevices - Time-domain spectroscopy and imaging in the THz range T. González - Nanodevices for THz Applications December 12, 2012 Research Group on Semiconductor Devices http://campus.usal.es/~gelec/ CONTACT: Prof. Tomás González ([email protected]) Staff: 8 permanent researchers, 3 post-doc, 2 students Collaborations with several EU (IEMN, Chalmers, Manchester, Montpellier, etc.) and USA Labs. (Rochester) Monte Carlo simulation of high-frequency nanodevices InGaAs/InAlAs, InAs/AlSb and GaN/AlGaN HEMTs RESEARCH LINES (FP6 project METAMOS) Advanced Si MOSFETs InGaAs based THz ballistic nanodevices (FP5 project NANOTERA ) 100nm TBJs YBJs MUX/DEMUX SSDs Coordinator of the FP7 STREP Project ROOTHz (FP7-243845) Characterization Laboratory (DC-GHz) Semiconductor Nanodevices for Room Temperature THz Emission and Detection - http://www.roothz.eu/ GaN diodes InGaAs/InAlAs diode Research Group on Semiconductor Devices EQUIPMENT Computer Clusters Probe station (Cascade M150) Keithley 4200: DC and pulsed VNA Agilent PNA-X: measurements (Keithley 4225) RF measurements up to 43.5 GHz THz Laboratory Contact: Dr. Yahya Meziani ([email protected]) Plasma-wave nanodevices A glimpse of the considered structures: Doubly interdigitated grating Strained Si/SiGe n-MODFET gates in III-V HEMT THz detectors based on Graphene transistors THz Laboratory Si/SiGe MODFETs used as sensors in THz signals detection Si/SiGe MODFETs used as sensors in THz imaging THz Laboratory Facilities Terahertz Spectroscopy System Probestation THz-Time Domain Spectroscopy System: EKSPLA Cascade Summit 11000B manual probestation with Spectrometer+Ti:Sapphire Laser (Spectra-Physics) FemtoGuard® and PurelineTM technologies (200mm-chuck) THz imaging: Gunn Diode at 0.2TH + frequency tripler + Agilent B1500 (4 SMUs, 1 multifreq CMU and 1 WG/FMU Outline Outline Introduction. Importance of THz ROOTHz Project Self Switching Diodes (SSDs) Conclusions / Perspectives T. González - Nanodevices for THz Applications December 12, 2012 The THz Band 1 THz = 1012 Hz THz range (100 GHz to 10 THz) (300 GHz to 3 THz, 1 - 0.1 mm) T. González - Nanodevices for THz Applications December 12, 2012 Potential applications THz radiation can penetrate poor weather, dust and smoke far better than infrared or visible systems. Aeronautics: guidance and landing Satellite Telemetry Image of sea surface temperature (European Space Agency) T. González - Nanodevices for THz Applications December 12, 2012 Potential applications: medical diagnosis THz radiation can penetrate organic materials without ionizing Readily absorbed by water: distinguish between materials with varying water content Medical imaging Skin Cancer Detection Courtesy of Teraview Courtesy of Teraview T. González - Nanodevices for THz Applications December 12, 2012 Potential applications: security THz radiation can penetrate dielectrics such as windows, paper, clothing and in certain instances even walls T. González - Nanodevices for THz Applications December 12, 2012 Potential applications: testing THz radiation can penetrate dielectrics such as windows, paper, clothing and in certain instances even walls Non-destructive testing: integrated circuit package inspection Courtesy of Teraview T. González - Nanodevices for THz Applications December 12, 2012 Potential applications: security THz radiation can penetrate dielectrics such as windows, paper, clothing and in certain instances even walls THz radiation can penetrate organic materials without ionizing Weapon or Explosive Detection (metallic or non metallic) Courtesy of Qinetiq Courtesy of Qinetiq Courtesy of Thruvision T. González - Nanodevices for THz Applications December 12, 2012 Potential applications: security THz radiation can penetrate dielectrics such as windows, paper, clothing and in certain instances even walls Full-body security screening, body scanners Passive Detection - no THz source is needed T. González - Nanodevices for THz Applications December 12, 2012 Potential applications: spectroscopy THz radiation can be used to identify spectral fingerprints of explosives, narcotics, or active pharmaceutical ingredients THz Spectroscopy Active Detection - THz sources are needed (narrow or broadband) Driving force of THz technology so far: spectroscopy, imaging, sensing T. González - Nanodevices for THz Applications December 12, 2012 Potential applications: communications T. González - Nanodevices for THz Applications December 12, 2012 Evolving THz market T. González - Nanodevices for THz Applications December 12, 2012 The THz gap PHOTONICS THz Gap ELECTRONICS All-optical sources All-electronic sources • Mixing lasers with close frequencies • Gunn diodes + frequency multipliers (Schottky diodes) • Excitation of semiconductors or superconductors with fs laser pulses • Quantum cascade lasers Very low power in the THz range Bulky and expensive equipment Backward wave oscillators - BWOs Useful for spectroscopy and sensing, but (vacuum electronic device) not for communications T. González - Nanodevices for THz Applications December 12, 2012 The THz gap Signal generation at THz frequencies 500 GHz – 5 THz Quantum cascade lasers (QCL) QCL at cryogenic T Frequency multipliers _ Other electronic devices: amplifiers, RTDs, IMPATT and Gunn diodes SemiconductorPROBLEM Nanodevices for RoomLack Temperature of a compact, THz room-temperature, The THz Gap Emissionhigh-power, and semiconductor Detection (ROOTHztunable source Project) Source: T. H. Crowe, W. L. Bishop, D. W. Porterfield, J. L. Hesler, and R. M. Weikle “Opening the Terahertz Window with Integrated Diode Circuits” IEEE J. Solid-State Circuits 40, 2104 (2005) T. González - Nanodevices for THz Applications December 12, 2012 Outline Outline Introduction. Importance of THz ROOTHz Project Self Switching Diodes (SSDs) Conclusions / Perspectives T. González - Nanodevices for THz Applications December 12, 2012 The Project Semiconductor Nanodevices for Room Temperature THz Emission and Detection (ROOTHz Project) • Funded under: 7th FWP (Seventh Framework Programme) • Area: FET Open (ICT-2007.8.0) • Project Reference: 243845 • Total cost: 2.1 M€ • EU contribution: 1.57 M€ • Execution: from 1st January 2010 to 30th June 2013 • Duration: 42 months • Website: www.roothz.eu T. González - Nanodevices for THz Applications December 12, 2012 Partners J. Grahn Chalmers University of Technology Gothenburg, Sweden A.M. Song The University of Manchester Manchester, UK C. Gaquiere Coordinator: J. Mateos Institut d’Electronique Microélectronique University of Salamanca et de Nanotechnologie, Lille, France Salamanca, Spain T. González - Nanodevices for THz Applications December 12, 2012 Semiconductor nanodevices in ROOTHz Final objective: fabrication of THz detectors and emitters with the same technology Self Switching Diodes (SSDs) Ohmic Ohmic Contact Contact Contact Contact Insulating Trenches Current Cap Layer Top View Barrier Channel Narrow Bandgap Buffer Wide Bandgap Semiconductors (NBG): Semiconductors (WBG): InGaAs/AlInAs GaN/AlGaN InAs/AlSbSlot Diodes (Ungated HEMTs) T. González - Nanodevices for THz Applications December 12, 2012 Outline Outline Introduction. Importance of THz ROOTHz Project Self Switching Diodes (SSDs) Conclusions / Perspectives T. González - Nanodevices for THz Applications December 12, 2012 Self-Switching Diodes (SSDs) 1 µm 3.0 2.5 W approx. 60 nm 2.0 A) W approx. 70 nm 1.5 1.0 Current ( 0.5 0.0 -0.5 -3 -2 -1 0 1 2 3 V (V) – – – – – nanochannel d doping + + + + + InP – + InP – – – – – + + + + + InGaAs V<0, channel closed V>0, channel open InP - substrate InGaAs channel T. González - Nanodevices for THz Applications December 12, 2012 Self-Switching Diodes (SSDs) Simple technological Tuneable threshold voltage process: etching of insulating from almost zero to more than trenches on a semiconductor ten volts by adjusting the surface channel width Easy downscaling and parallelization: THz Adequate geometry operation can be for the onset of Gunn obtained oscillations T. González - Nanodevices for THz Applications December 12, 2012 Self-Switching Diodes (SSDs) • THz Detection: non-linear I-V characteristics Use of NBG materials (Room Temperature ballistic transport) for increased sensitivity and broadband • THz Emission: Gunn Effect in InGaAs, and GaN !! Use of WBG materials for increased power and frequency • Planar geometry (and antennas) allow for a better coupling • Parallelization for enhanced performances (and correct thermal management) T. González - Nanodevices for THz Applications December 12, 2012 Outline Outline Introduction. Importance of THz ROOTHz Project Self Switching Diodes (SSDs) SSDs as THz detectors Conclusions / Persp. SSDs as THz emitters T. González - Nanodevices for THz Applications December 12, 2012 SSDs as THz detectors: experiments B 20 V 16 12 A) 8 2DEG 4 Current ( 0 4 diodes in 3 m -4 parallel -1.0 -0.5 0.0 0.5 1.0 Voltage (V) 0 1 mm -5 RoomResponsivity temperature 1330THz V/W detection @ 12 K -10 -15 150 mV/mW Free Electron Laser at 1.5 THz -20 -25 -30 300 mV/mW T = 300 K Output DC Voltage (mV) Voltage DC Output -35 0.0 0.2 0.4 0.6 0.8 C. Balocco et al., Appl. Phys. Lett. 98, 223501 (2011) Bias Current (A) T. González - Nanodevices