63 Result(s)
within
J Han
Materials Science, general
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Article
High sensitivity of hydrogen sensing through N-polar GaN Schottky diodes
N-polar and Ga-polar GaN grown on c-plane sapphire by a metal-organic chemical vapor deposition (MOCVD) system were used to fabricate platinum deposited Schottky contacts for hydrogen sensing at room temperatu...
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Article
Comparison of Implant Isolation Species for GaN Field-Effect Transistor Structures
Different ions (Ti+, O+, Fe+, Cr+) were implanted at multiple energies into GaN field effect transistor structures (n and p-type). The implantation was found to create deep states with energy levels in the range ...
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Article
Properties and Effects of Hydrogen in GaN
The status of understanding of the behavior of hydrogen in GaN and related materials is reviewed. In particular, we discuss the amount of residual hydrogen in MOCVD-grown device structures such as heterojuncti...
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Article
Optical Spectroscopy of Ingan Epilayers in the Low Indium Composition Regime
Photoluminescence (PL) spectroscopy was carried out on a series of Si-doped bulk InGaN films in the low indium (In) composition regime. Room temperature PL showed a factor of 25 increase in integrated intensit...
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Article
Simulation of H Behavior in p-GaN(Mg) at Elevated Temperatures
The behavior of H in p-GaN(Mg) at temperatures >400°C is modeled by using energies and vibration frequencies from density-functional theory to parameterize transport and reaction equations. Predictions agree s...
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Article
Processing and Device Performance of GaN Power Rectifiers
Mesa and planar geometry GaN Schottky rectifiers were fabricated on 3-12µm thick epitaxial layers. In planar diodes utilizing resistive GaN, a reverse breakdown voltage of 3.1 kV was achieved in structures con...
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Article
Lattice Location of Deuterium in Plasma and Gas Charged Mg Doped GaN
We have used ion channeling to examine the lattice configuration of deuterium in Mg doped GaN grown by MOCVD. The deuterium is introduced by exposure to gas phase or ECR plasmas. A density functional approach ...
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Article
The Behavior of Ion-Implanted Hydrogen in Gallium Nitride
Hydrogen was ion-implanted into wurtzite-phase GaN, and its transport, bound states, and microstructural effects during annealing up to 980°C were investigated by nuclear-reaction profiling, ion-channeling ana...
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Article
Group-III Nitride Etch Selectivity in BCl3/Cl2 ICP Plasmas
Patterning the group-III nitrides has been challenging due to their strong bond energies and relatively inert chemical nature as compared to other compound semiconductors. Plasma etch processes have been used ...
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Article
Rapid Thermal Processing of Implanted GaN Up to 1500°C
GaN implanted with donor(Si, S, Se, Te) or acceptor (Be, Mg, C) species was annealed at 900-1500°C using AIN encapsulation. No redistribution was measured by SIMS for any of the dopants and effective diffusion...
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Article
Microstructure of GaN Grown on (111) Si by MOCVD
Gallium nitride was grown on (111) Si by MOCVD by depositing an AlN buffer at 1080°C followed by GaN at 1060°C. The 2.2 μm layer cracked along {1-100} planes upon cooling to room temperature, but remained adhe...
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Article
Photoelectrochemical Etching of InxGal−xN
A comparison of KOH, NaOH and AZ400K solutions for UV photo-assisted etching of undoped and n+ GaN is discussed. The etching is diffusion-limited (Ea < 6kCal-mol-1) under all conditions and is significantly faste...
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Article
Activation Characteristics of Donor and Acceptor Implants in GaN
The ionization levels of different donor and acceptor species implanted into GaN were measured by temperature-dependent Hall data after high temperature (1400 °C) annealing. The values obtained were 28 meV (Si...
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Article
Near infrared imaging of micro-structured polymer-metal surface pattern
Two-dimensional infrared scanning microscopy images of micro-structured surface patterns in an organic transistor device with metal electrode stripes on a polymer channel layer have been demonstrated. A compac...
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Article
Multimodal biometric authentication based on score level fusion using support vector machine
Fusion of multiple biometrics for human authentication performance improvement has received considerable attention. This paper presents a novel multimodal biometric authentication method integrating face and i...
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Article
MOCVD Growth and Characterization of AlGaInN Nanowires and Nanostructures
Growth of GaN and AlGaInN nanowires using metalorganic chemical vapor deposition (MOCVD) is investigated. It is determined that surface kinetics play an important role in non-equilibrium synthesis process such...
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Article
In situ TEM Observations of Grain Growth in Nanograined Thin Films
In situ transmission electron microscopy analysis is used to study the stability of nanograined and ultra-fine grained thin films at elevated temperatures. In the free-standing Au and Cu films, grain growth was d...
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Article
In situ transmission electron microscopy observations of toughening mechanisms in ultra-fine grained columnar aluminum thin films
A unique straining device, fabricated using microlithographic techniques, has been developed to permit real-time investigation in the transmission electron microscope (TEM) of the deformation and failure mecha...
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Article
Growth, Characterization, and Application of High Al-content AlGaN and High Power III-Nitride Ultraviolet Emitters
A study of Si-doped and Mg-doped AlxGa1-xN up to x ~ 50 % and the characteristics of ultraviolet (UV) light emitting diodes (LEDs) with emission wavelengths at 340 nm and 290 nm are reported. By using grading sup...
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Article
Vapor-liquid-solid Growth of III-Nitride Nanowires and Heterostructures by Metal-Organic Chemical Vapor Deposition
We report flexible synthesis of III-Nitride nanowires and heterostructures by metal-organic chemical vapor deposition (MOCVD) via a catalytic vapor-liquid-solid (VLS) growth mechanism. Indium is used as an in-...
