-
Article
Nonradiative Recombination, Carrier Localization, and Emission Efficiency of AlGaN Epilayers with Different Al Content
The interplay between nonradiative recombination and carrier localization in Al x Ga1−x N epilayers (0.11 < x < 0.78) was studied using the photoluminesce...
-
Article
Negative Differential Conductivity in AlGaN/GaN HEMTs: Real Space Charge Transfer from 2D to 3D GaN States?
We report on non-thermal negative differential conductivity (NDC) in AlGaN/GaN HEMTs grown on sapphire substrates by low-pressure MOCVD. The sheet electron density was on the order of few times 1012cm−2 and the H...
-
Article
Low-Frequency Noise in SiO2/AlGaN/GaN Heterostructures on SiC and Sapphire Substrates
The low-frequency noise in GaN-based Metal-Oxide-Semiconductor Heterostructure Field Effect Transistors (MOS-HFETs) and HFETs on sapphire and n-SiC substrates were studied. Hooge parameter at zero gate bias wa...
-
Article
The Influence of Substrate Surface Polarity on Optical Properties of GaN Grown on Single Crystal Bulk AlN
Photoluminescence of the GaN layers grown both on N-face and Al-face bulk AlN is studied under CW and pulsed laser excitation in the temperature range from 8 K to 300 K. We compare localization of excitons, re...
-
Article
Growth and Characterization of Deep UV Emitter Structures Grown on Single Crystal Bulk AlN Substrates
We report on high Al-content AlGaN-based deep UV emitter structures grown over single crystal, slightly off c-axis (5.8 degrees) bulk AlN substrates. AlN/AlGaN multiple quantum well (MQW) structures with up to...
-
Article
Disorder Induced IR Anomaly in Hexagonal AlGaN Short-Period Superlattices and Alloys
We report an experimental (infrared reflectance spectroscopy) and theoretical study of the polar optical phonons in hexagonal ternary nitride compounds: AlNm/GaNn (n=2-8, m=4, 8) superlattices (SL) and spontaneou...
-
Article
Pyroelectric and Piezoelectric Properties of Gan-Based Materials
We review pyroelectric and piezoelectric properties of GaN-based materials. Pyroelectric effects in GaN have been studied in two different regimes: (i) uniform sample heating regime and (ii) under applied temp...
-
Article
Progress in the Preparation of Aluminum Nitride Substrates from Bulk Crystals
Large (11-mm diameter) single-crystal AlN boules have been prepared using sublimationrecondensation growth. X-ray topography shows that substrates prepared from those boules have a dislocation density of less ...
-
Article
Stimulated Emission at 258 nm in AlN/AlGaN Quantum Wells Grown on Bulk AlN Substrates
We report on observation of stimulated emission at 258 nm in AlN/AlGaN multiple quantum wells. The structures were grown over Al-face single crystal bulk AlN substrates. AlN/AlGaN structures with 50% of Al in ...
-
Chapter
Insulated Gate Nitride-Based Field Effect Transistors
Polarization do** related to the piezoelectric and spontaneous polarization induced electric fields in nitride-based (III-N) semiconductors and large conduction and valence band discontinuities at the hetero...
-
Article
Study of Optical Gain in Thick GaN Epilayers by Variable Stripe Length Technique
We report on the gain study in high-quality thick GaN layers using the Variable Stripe Length (VSL) technique. The layers were grown by Migration Enhanced Metal Organic Chemical Vapor Deposition (MEMOCVD™). Th...
-
Chapter and Conference Paper
III-Nitride Based UV Light Emiting Diodes
The development of deep UV LEDs requires growing high quality AlGaN epitaxial layers with high molar fractions of Al. Our Strain Energy Band Engineering approach has considerably improved the quality of such l...
-
Chapter and Conference Paper
III-Nitride Based Ultraviolet Surface Acoustic Wave Sensors
Large piezoelectric constants of AIN, GaN, and their alloys make these materials attractive for applications involving surface acoustic waves (SAW). The electrical conductivity and, thus, SAW velocity in these...
-
Chapter and Conference Paper
Optical Measurements Using Light-Emitting Diodes
Recent advances in optical measurements using light-emitting diodes (LEDs) are reviewed. The review covers applications of LEDs as stable and compact sources of light, fluorometry including fluorescence lifeti...
-
Article
Quaternary AlInGaN MQWs for Ultraviolet LEDs
We report a pulsed atomic layer epitaxy (PALE) growth technique for quaternary AlInGaN films for ultraviolet optoelectronic applications. Using the PALE approach high quality quaternary AlInGaN/AlInGaN multipl...
-
Article
High Magnetic Field Studies of AlGaN/GaN Heterostructures Grown on Bulk GaN, SiC, and Sapphire Substrates
We present the results of the high magnetic field studies of properties of two-dimensional electron gas (2DEG) in AlGaN/GaN heterostructures grown over high-pressure bulk GaN, sapphire, and insulating SiC subs...
-
Article
Two-dimensional electron gas scattering mechanisms in AlGaN/GaN heterostructures
We present the results of the experimental and theoretical studies of the low field mobility of two-dimensional electrons in the homoepitaxial AlGaN/GaN heterostructures and in the AlGaN/GaN heterostructures g...
-
Article
Low-Frequency Noise in SiO2/AlGaN/GaN Heterostructures on SiC and Sapphire Substrates
The low-frequency noise in GaN-based Metal-Oxide-Semiconductor Heterostructure Field Effect Transistors (MOS-HFETs) and HFETs on sapphire and n-SiC substrates were studied. Hooge parameter at zero gate bias wa...
-
Article
Negative Differential Conductivity in AlGaN/GaN HEMTs: Real Space Charge Transfer from 2D to 3D GaN States?
We report on non-thermal negative differential conductivity (NDC) in AlGaN/GaN HEMTs grown on sapphire substrates by low-pressure MOCVD. The sheet electron density was on the order of few times 1012cm−2 and the H...
-
Article
Pyroelectric and Piezoelectric Properties of GaN-Based Materials
We review pyroelectric and piezoelectric properties of GaN-based materials. Pyroelectric effects in GaN have been studied in two different regimes: (i) uniform sample heating regime and (ii) under applied temp...
