A5007271458- GaN-based semiconductor devices and materials
- Semiconductor Quantum Structures and Devices
- Semiconductor materials and devices
- Silicon and Solar Cell Technologies
- Thin-Film Transistor Technologies
- Ga2O3 and related materials
- Silicon Nanostructures and Photoluminescence
- Semiconductor Lasers and Optical Devices
- Metal and Thin Film Mechanics
- Semiconductor materials and interfaces
- Photonic and Optical Devices
- ZnO doping and properties
- Photocathodes and Microchannel Plates
- Acoustic Wave Resonator Technologies
- Nanowire Synthesis and Applications
- Microfluidic and Bio-sensing Technologies
- Microfluidic and Capillary Electrophoresis Applications
- Advanced Fiber Laser Technologies
- Electron and X-Ray Spectroscopy Techniques
- Advanced Fiber Optic Sensors
- Laser Material Processing Techniques
- Photonic Crystals and Applications
- Ion-surface interactions and analysis
- Biosensors and Analytical Detection
- Advancements in Semiconductor Devices and Circuit Design
Palo Alto Research Center
2013-2023
Xerox (France)
2014
Xerox (United States)
2013
Technische Universität Berlin
2010
Washington State University
1999-2001
Northwestern University
1999
Fritz Haber Institute of the Max Planck Society
1999
Sandia National Laboratories
1994
Stanford University
1993
Friedrich-Alexander-Universität Erlangen-Nürnberg
1990
Abstract Ultrawide‐bandgap (UWBG) semiconductors, with bandgaps significantly wider than the 3.4 eV of GaN, represent an exciting and challenging new area research in semiconductor materials, physics, devices, applications. Because many figures‐of‐merit for device performance scale nonlinearly bandgap, these semiconductors have long been known to compelling potential advantages over their narrower‐bandgap cousins high‐power RF electronics, as well deep‐UV optoelectronics, quantum...
The field of AlGaInN ultraviolet UV light-emitting diodes (LEDs) is reviewed, with a summary the state-of-the-art in device performance and enumeration applications. Performance-limiting factors for high-efficiency LEDs are identified recent advances development deep emitters presented.
The activation kinetics of acceptors was investigated for heteroepitaxial layers GaN, doped with Mg. After growth, the samples were exposed to isochronal rapid thermal anneals in temperature range from 500 775 °C. studied by variable Hall effect measurements and photoluminescence (PL) spectroscopy as-grown condition after each step. treatment reduced resistivity six orders magnitude p-type conductivity found be dominated an acceptor energy ∼170 meV. This is attributed Mg atoms substituting...
The electronic properties of Si donors in heteroepitaxial layers GaN were investigated. n-type grown by metalorganic chemical vapor deposition and either intentionally doped with or unintentionally doped. samples evaluated variable temperature Hall effect measurements photoluminescence (PL) spectroscopy. For both types the conductivity was found to be dominated a donor an activation energy between 12 17 meV. This is attributed atoms substituting for Ga lattice (SiGa). range energies due...
It is demonstrated for the first time that hydrogen can passivate shallow-donor impurities in n-type single-crystal silicon, and a novel chemical-bonding model proposed to explain phenomenon. Phosphorus greatly slows bulk diffusion of at \ensuremath{\sim}150 \ifmmode^\circ\else\textdegree\fi{}C. Conductivity Hall measurements show room-temperature electron density decreased by hydrogenation, but mobility increased, so compensation ruled out. Total-energy calculations predict an energy...
The band-gap energy distribution of Pb centers on oxidized (100) Si wafers has been determined and compared with interface electrical trap density Dit. Two different are observed Si: Pb0, which the structure ⋅Si≡Si3, is essentially identical to sole center (111) Si; Pb1, presently uncertain identity, but clearly in nature from Pb0. By electric field-controlled electron paramagnetic resonance (EPR) capacitance-voltage (C-V) measurements, it found that Pb0 its (0↔1) transition at Ev+0.3 eV...
Indium–gallium nitride (InGaN) multiple-quantum-well (MQW) light-emitting diode (LED) membranes, prefabricated on sapphire growth substrates, were created using pulsed-excimer laser processing. The thin-film InGaN MQW LED structures, grown first bonded onto a Si support substrate with an ethyl cyanoacrylate-based adhesive. A single 600 mJ/cm2, 38 ns KrF (248 nm) excimer pulse was directed through the transparent sapphire, followed by low-temperature heat treatment to remove substrate....
We report unidirectional emission from lasing in In0.09Ga0.91N/In0.01Ga0.99N multiple-quantum-well spiral micropillars. Our imaging technique shows that the maximum comes notch of microcavities at an angle about 40° normal notch. At room temperature, microcavity lases near 400 nm when optically pumped with 266 or 355 light. A reduction threshold and improvement unidirectionality occurs is selectively its boundary.
Band gap measurements have been performed on strained InxGa1−xN epilayers with x⩽0.12. The experimental data indicate that the bowing of band is much larger than commonly assumed. We first-principles calculations for as a function alloy composition and find strongly dependent. At x=0.125 calculated parameter b=3.5 eV, in good agreement values.
Local vibrational modes (LVMs) are reported for Mg-doped GaN grown by metalorganic chemical vapor deposition. Hetero-epitaxial layers of GaN:Mg, either as-grown, thermally activated, or deuterated, were investigated with low-temperature, Fourier-transform infrared absorption spectroscopy. The as-grown material, which was semi-insulating, exhibits a LVM at 3125 cm−1. Thermal annealing increases the p-type conductivity, as established Hall effect measurements, and proportionally reduces...
Evidence is presented for phase separation in In0.27Ga0.73N/GaN multiple quantum wells. After annealing 40 h at a temperature of 950 °C, the absorption threshold 2.95 eV replaced by broad peak 2.65 eV. This attributed to formation In-rich InGaN phases active region. X-ray diffraction measurements show shift peaks toward GaN, consistent with an In-poor phase. A corresponding also present annealed material. Nanoscale precipitates are observed transmission electron microscopy and energy...
It is shown for the first time that hydrogen passivation of p-type GaAs produces electrical compensation shallow-acceptor impurity. This demonstrated with capacitance-voltage and secondary-ion-mass spectrometry measurements on hydrogenated Zn-doped GaAs. In addition, it comparable net dopant concentrations, far more extensive in as compared to n-type GaAs; both metal-organic chemical-vapor-deposited (Zn Se doped) bulk Si were investigated. proposed Zn acceptors involves interstitial...
The polarization of the in-plane electroluminescence (0001) orientated (In)(Al)GaN multiple quantum well light emitting diodes in ultraviolet-A and ultraviolet-B spectral range has been investigated. intensity for transverse-electric polarized relative to transverse-magnetic decreases with decreasing emission wavelength. This effect is attributed rearrangement valence bands at Γ-point Brillouin zone changing aluminum indium mole fractions wells. For shorter wavelength crystal-field split-off...
Current-injection ultraviolet lasers are demonstrated on low-dislocation-density bulk AlN substrates. The AlGaInN heterostructures were grown by metalorganic chemical vapor deposition. Requisite smooth surface morphologies obtained growing near-c-plane substrates, with a nominal off-axis orientation of less than 0.5°. Lasing was from gain-guided laser diodes uncoated facets and cavity lengths ranging 200 to 1500 μm. Threshold current densities as low 13 kA/cm2 achieved for emission...
Low phase noise lasers based on the combination of III-V semiconductors and silicon photonics are well established in near-infrared spectral regime. Recent advances development low-loss nitride-based photonic integrated resonators have allowed to outperform bulk external diode fiber both frequency agility 1550 nm-telecommunication window. Here, we demonstrate for first time a hybrid laser composed gallium nitride (GaN) chip-based microresonator operating at record low wavelengths as 410 nm...
Indium–gallium nitride (InxGa1−xN) single-quantum-well (SQW) light emitting diodes (LEDs), grown by metalorganic chemical vapor deposition on sapphire, were transferred onto Si substrates. The thin-film InxGa1−xN SQW LED structures first bonded a n+-Si substrate using transient-liquid-phase Pd–In wafer-bonding process followed laser lift-off technique to remove the sapphire growth substrate. Individual, 250×250 μm2, LEDs with backside contact through then fabricated. had typical turn-on...
Experimental and theoretical evidence is presented for the metastability of oxygen donors in ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{N}$. As aluminum content increases, Hall effect measurements reveal an increase electron activation energy, consistent with emergence a deep $\mathrm{DX}$ level from conduction band. Persistent photoconductivity observed ${\mathrm{Al}}_{0.39}{\mathrm{Ga}}_{0.61}\mathrm{N}:\mathrm{O}$ at temperatures below 150 K after exposure to light, optical...
A spiral-shaped microcavity heterojunction laser diode fabricated with InGaN multiple quantum wells is demonstrated to operate under current injection conditions and emit unidirectionally. Room-temperature operation was achieved for disk radii ranging from 50 350 μm threshold densities as low 4.6 kA/cm2. Unidirectional emission clearly revealed in the far-field pattern lateral divergence angle 60° 75°. Output power of more than 25 mW obtained wavelengths near 400 nm.
The effects of the deliberate hydrogenation GaN were investigated for heteroepitaxial layers grown by metalorganic chemical vapor deposition. either Mg-doped, p-type after thermal activation, or Si-doped, n type. Elemental depth profiles from secondary ion mass spectroscopy reveal a striking contrast deuteration at 600 °C: deuterium concentration in Mg-doped is ∼1019 cm−3 while there no detectable incorporation n-type material. Variable temperature Hall effect measurements provide most...
We present the results of optical studies properties InxGa1−xN epitaxial layers (0<x<0.2) grown by metalorganic chemical vapor deposition. The effects alloying on fundamental band gap were investigated using a variety spectroscopic techniques. band-gap energies alloys determined photomodulation spectroscopy measurements and variation was measured as function temperature. pressure for samples with different alloy concentrations examined studying shift photoluminescence (PL)...
Hole concentrations of up to 1019 cm−3 have been reported for GaN:Mg films grown by molecular beam epitaxy without any post-growth treatment. Comparing results from Hall measurements and secondary ion mass spectrometry, we observe doping efficiencies 10% at room temperatures in such p-type material. By hydrogenating above 500 °C, the hole concentration can be reduced an order magnitude. A new photoluminescence line 3.35 eV is observed after this treatment, both unintentionally doped n-type...
It is demonstrated that hydrogen can migrate in silicon as a negatively charged species (${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$). The evidence the combined observation of strong electric-field dependence rate removal PH complexes during bias-temperature stress hydrogenated Schottky-barrier diodes and resulting spatial redistribution neutralized donors. detection ${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$ establishes that, addition to previously determined deep-donor level, there also exists...
Electron injection into ultrathin nitrided oxides on silicon reveals both high densities of electronic defects, which readily capture electrons, and efficient tunnel emission trapped charge. High-temperature nitridation thermally grown was verified with Auger depth profiling. In 11–17-nm-thick oxides, the electron trap density is ≥1×1019 cm−3 as determined from saturated charge accumulation, majority traps are energetically situated more than 2 eV below conduction band by post-injection...