Michael Shur

AlGaN/GaN metal oxide semiconductor heterostructure field effect transistor

We report on the AlGaN/GaN metal oxide semiconductor heterostructure field effect transistor (MOS-HFET) and present the results of the comparative studies of this device and a base line AlGaN/GaN heterostructure field effect transistor (HFET). For a 5-/spl mu/ source-to-drain opening, the maximum current was close to 600 mA/mm for both devices. The gate leakage current for the MOS-HFET was more than six orders of magnitude smaller than for the HFET.

Electron transport in wurtzite indium nitride

We present the velocity-field characteristics of wurtzite indium nitride, determined using an ensemble Monte Carlo approach. It is found that indium nitride exhibits an extremely high peak drift velocity at room temperature, 4.3×107u2009cm/s, at a doping concentration of 1.0×1017u2009cm−3. We also demonstrate that the saturation drift velocity of indium nitride, 2.5×107u2009cm/s, is comparable to that of gallium nitride, and much larger than that of gallium arsenide. Our results suggest that the transport characteristics of indium nitride are superior to those of gallium nitride and gallium arsenide, over a wide range of temperatures, from 150 to 500 K, and doping concentrations, up to 1.0×1019u2009cm−3. Hence, indium nitride has considerable potential for device applications.

Pyroelectricity in gallium nitride thin films

We report on the measurements of the pyroeffect in wurtzite n‐type GaN films deposited over basal plane sapphire substrates. We measured the voltage drop between the contacts while the sample was subjected to the uniform heating or cooling. The pyroelectric voltage coefficient extracted from our data is comparable to that of the pyroelectric ceramics (∼104 V/mu2009K). Our results show that the pyroelectric effect in GaN is a combination of a fast response to an initial heat flow and a slower response related to a change in the sample temperature.

Terahertz sensing technology

Sensing applications of THz technology include applications for space exploration, detection of concealed objects, explosive identification, and THz cancer detection. This paper will review these and other emerging applications and existing and potential THz sources and detectors, including photonic and electronic THz devices, such as plasmonic field effect transistors capable of detecting and emitting THz radiation. Plasma wave electronics devices demonstrated THz detection using GaAs-based and GaN-based HEMTs, Si MOS, SOI, and FINFETs and FET arrays. This technology has potential to become a dominant THz electronics technology.

Plasma Wave Electronics

Plasma waves are oscillations of electron density in time and space. In deep submicron field effect transistors plasma wave frequencies lie in the terahertz range and can be tuned by applied gate bias. Since the plasma wave frequency is much larger that the inverse electron transit time in the device, it is easier to reach ballistic regimes for plasma waves than for electrons moving with drift velocities. In the ballistic regime, no collisions of electrons with impurities or lattice vibrations occur on a time scale on the order of the plasma oscillation period, and the device channel acts as a resonant cavity for the plasma waves, making possible tunable resonant detection or even emission of the electromagnetic radiation in the terahertz range. We review the theory of plasma waves in field effect transistors; discuss instabilities of these waves in different device structures and their applications for detection and generation of the terahertz radiation.

GaN-based materials and devices : growth, fabrication, characterization and performance

The unique materials properties of GaN-based semiconductors have stimulated a great deal of interest in research and development regarding nitride materials growth and optoelectronic and nitride-based electronic devices. High electron mobility and saturation velocity, high sheet carrier concentration at heterojunction interfaces, high breakdown field, and low thermal impedance of GaN-based films grown over SiC or bulk AIN substrates make nitride-based electronic devices very promising. The chemical inertness of nitrides is another key property. This volume, written by experts on different aspects of nitride technology, addresses the entire spectrum of issues related to nitride materials and devices, and it will be useful for technologists, scientists, engineers, and graduate students who are working on wide bandgap materials and devices. The book can also be used as a supplementary text for graduate courses on wide bandgap semiconductor technology.

UV solid-state light emitters and detectors

Contributing Authors. Preface. Basic Device Issues in UV Solid-State Emitters and Detectors M.S. Shur, A. Zukauskas. HVPE-Grown AlN-GaN Based Structures for UV Spectral Region A.S. Usikov, et al. GaN-Based Laser Diodes S. Einfeldt, et al. Quaternary AlInGaN Materials System for UV Optoelectronics E. Kuokstis, et al. III-Nitride Based UV Light Emitting Diodes R. Gaska, et al. UV Metal Semiconductor Metal Detectors J.-L. Reverchon, et al. Characterization of Advanced Materials for Optoelectronics by Using UV Lasers and Four-Wave Mixing Techniques K. Jarasiunas. Quantum Phosphors A.P. Vink, et al. Optical Measurements Using Light-Emitting Diodes A. Zukauskas, et al. Novel AlGaN Heterostructures for UV Sensors and LEDs M. Stutzmann. Nitride Photodetectors in UV Biological Effects Studies E. Munoz, et al. Promising Results of Plasma Assisted MBE for Optoelectronic Applications A. Georgakilas, et al. Low Dislocations Density GaN/Sapphire for Optoelectronic Devices B. Beaumont, et al. Stimulated Emission and Gain in GaN Epilayers Grown on Si A.L. Gurskii, et al. Materials Characterization of Group-III Nitrides under High-Power Photoexcitation S. Jursenas, et al. Small Internal Electric Fields in Quaternary InAlGaN Heterostructures S. Anceau, et al. MOCVD Growth of AlGaN Epilayers and AlGaN/GaN SLs in a Wide Composition Range W.V. Lundin, et al. Gallium Nitride Schottky Barriers and MSM UV Detectors B. Boratynski, M. Tlaczala. III-Nitride Based Ultraviolet Surface Acoustic Wave Sensors D. Ciplys, et al. Optically Pumped InGaN/GaN/AlGaN MQW Laser Structures V.Yu. Ivanov, et al. High Power LED and Thermal Management A. Mahlkow. Detection of Blue Light by Self-Assembled Monolayer of Dipolar Molecules O. Nielands, et al. Atomic and Molecular Spectroscopy with UV and Visible Superbright LEDs G. Pichler, et al. Semi-Insulating GaN and its First Tests for RadiationHardness as an Ionizing Radiation Detector J.V. Vaitkus, et al. Towards the Hybrid Biosensors Based on Biocompatible Conducting Polymers A. Ramanaviciene, A. Ramanavicius. Optically Pumped UV-Blue Lasers Based on InGaN/GaN/Al2O3 and InGaN/GaN/Si Heterostructures G.P. Yablonskii, et al. Key Word Index. Author Index.

Terahertz Science and Technology for Military and Security Applications

Fire Damage on Carbon Fiber Materials Characterized by THz Waves (N Karpowicz) Fingerprinting Insulins in the Spectral Region from Mid-IR to THz (R Song) Ambient Air Used as the Nonlinear Media for THz Wave Generation (X Xie) Time Domain Terahertz Imaging of Threats in Luggage and Personnel (D Zimdars) Designed Self-Organization for Molecular Optoelectronic Sensors (M Norton) An Optically-Triggered I-RTD Hybrid THz Oscillator Design (D Woolard) New Technique to Suppress Sidelobe Clutter in Perimeter Security Systems (G W Webb) Remote Identification of Foreign Subjects (A Sokolnikov) and other papers.

Low-frequency noise in GaN/GaAlN heterojunctions

We report on the results of the measurements of the low-frequency nitride/gallium aluminum nitride (GaN/GaAlN) heterojunctions grown on sapphire substrates. The noise spectra have the form of the 1/f noise with the Hooge parameter of approximately 10−2. The effects of band-to-band and impurity illumination on the low-frequency noise show that the nature of the 1/f noise in GaN might be a result of the occupancy fluctuations of the tail states near the band edges. This mechanism of the 1/f noise is similar to that in GaAs and Si.

GaN And Related Materials For High Power Applications

Unique properties of GaN and related semiconductors make them superior for high-power applications. The maximum density of the two-dimensional electron gas at the GaN/AlGaN heterointerface or in GaN/AlGaN quantum well structures can reach 5×10 13 cm −2 , which is more than an order of magnitude higher than for traditional GaAs/AlGaAs heterostructures. The mobility-sheet carrier concentration product for these two dimensional systems might also exceed that for GaAs/AIGaAs heterostructures and can be further enhanced by doping the conducting channels and by using “piezoelectric” doping, which takes advantage of high piezoelectric constants of GaN and related materials. We estimate that current densities over 20 A/mm can be reached in GaN-based High Electron Mobility Transistors (HEMTs). These high current values can be combined with very high breakdown voltages in high-power HEMTs. These breakdown voltages are expected to reach several thousand volts. Recent Monte Carlo simulations point to strong ballistic and overshoot effects in GaN and related materials, which should be even more pronounced than in GaAs-based compounds but at much higher electric fields. This should allow us to achieve faster switching, minimizing the power dissipation during switching events. Selfheating, which is unavoidable in power devices, raises operating temperatures of power devices well above the ambient temperature. For GaN-based devices, the use of SiC substrates having high thermal conductivity is essential for ensuring an effective heat dissipation. Such an approach combines the best features of both GaN and SiC technologies; and GaN/SiC-based semiconductors and heterostructures should find numerous applications in power electronics.