A5084003057- ZnO doping and properties
- Semiconductor Quantum Structures and Devices
- Ga2O3 and related materials
- GaN-based semiconductor devices and materials
- Quantum Dots Synthesis And Properties
- Chalcogenide Semiconductor Thin Films
- Advanced Semiconductor Detectors and Materials
- Copper-based nanomaterials and applications
- Semiconductor materials and devices
- Metal and Thin Film Mechanics
- Semiconductor materials and interfaces
- Electron and X-Ray Spectroscopy Techniques
- Surface and Thin Film Phenomena
- Electronic and Structural Properties of Oxides
- Magnetic and transport properties of perovskites and related materials
- Gas Sensing Nanomaterials and Sensors
- Luminescence Properties of Advanced Materials
- Acoustic Wave Resonator Technologies
- Semiconductor Lasers and Optical Devices
- Perovskite Materials and Applications
- Ion-surface interactions and analysis
- Force Microscopy Techniques and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Integrated Circuits and Semiconductor Failure Analysis
- Silicon Nanostructures and Photoluminescence
Dalian Jiaotong University
2023-2024
John Wiley & Sons (United States)
2022
Hudson Institute
2022
Moss Landing Marine Laboratories
2022
Tohoku University
2005-2016
National Chi Nan University
2010
Institute for Materials Research, Tohoku University
1997-2009
Wuhan University of Science and Technology
2005
Hirosaki University
2003
Joint Research Center
1997
We report the observation of optically pumped lasing in ZnO at room temperature. Thin films were grown by plasma-enhanced molecular beam epitaxy on (0001) sapphire substrates. Laser cavities formed cleaving found to lase a threshold excitation intensity 240 kW cm−2. believe these results demonstrate high quality epilayers while clearly demonstrating viability based light emitting devices.
The emission spectrum of high quality ZnO epilayers is studied from room temperature up to 550 K. At and low excitation power a single peak observed which may be identified with the free exciton its energy dependence on temperature. However, when intensities exceed 400 kW cm−2 sharp emerges at lower we attribute exciton-exciton scattering. higher (>800 cm−2) second stimulated even energies: this an electron hole plasma. Similar features are for all temperatures
We have investigated the structural and optical properties of Ga-doped ZnO films grown on GaN templates by plasma-assisted molecular-beam epitaxy. The carrier concentration in can be controlled from 1.33×1018/cm3 to 1.13×1020/cm3. Despite high Ga incorporation, linewidth (0002) ω-rocking curves still lies range 5 15 arc min. Photoluminescence (PL) spectra show dominant near-bandedge emission with negligibly weak deep-level emission, independent concentration. PL spectrum exhibits a new line...
Photoluminescence (PL) properties of ZnO films grown on CaF2(111) with a low-temperature buffer layer by plasma assisted molecular beam epitaxy are investigated, in which lattice misfit tensile strain is expected to be compensated the thermal compressive strain. The further introduced accommodate leading growth almost strain-free and high quality films. PL spectra layers measured at 10 K dominated neutral-donor bound exciton emission 3.366 eV (I4) linewidth 12 meV. Commonly observed deep...
The authors fabricated GaN-based light-emitting diodes (LEDs) on two different GaN templates with the same LED structure. One thin template (∼2μm) high dislocation density [low (109cm−2)] grown by metal-organic vapor-phase epitaxy (sample A) and other thick (∼20μm) comparatively low [high (108cm−2)] hydride B). In order to understand mechanism of leakage current in LEDs, correlation between current-voltage characteristics etch pit LEDs was studied.
Vertical light-emitting diodes (LEDs) were successfully fabricated by a chemical lift-off process using selectively etchable CrN buffer layer. The novel metallic layer worked well as for growth of the GaN LED and was etched out clearly during selective etching. vertical showed very good current-voltage performance with low series resistance 0.65 Omega operated voltage 3.11 V at 350 mA. Also, this device could be much higher injection forward current (1118 mA 3.70 V) thermally conductive...
We have investigated the optical and structural properties of high-quality ZnO films grown on epitaxial GaN (epi-GaN) by plasma-assisted molecular-beam epitaxy employing low-temperature buffer layers. High-resolution x-ray diffraction for both symmetric asymmetric reflexes shows that crystalline defects in a similarity to epi-GaN used as substrate. The quality epilayers is basically determined epi-GaN. photoluminescence (PL) spectrum at 10 K exhibits very sharp exciton emission with...
We report the origin of hexagonal-shaped etch pits generally observed by conventional wet etching processes on (0001) GaN-based films based investigation with transmission electron microscopy GaN after being etched molten KOH. The is identified as nanopipes through careful characterization abnormal contrast nanopipe (open-core screw dislocation), “lobe contrast” end-on edge and (full-core) dislocations, visible invisible conditions dislocations. Consideration energetics these defects also...
Hard x-ray valence band photoemission spectroscopy (PES) is realized using high-energy and high-brilliance synchrotron radiation. High-energy (∼6 keV) excitation results in larger probing depths of photoelectrons compared to conventional PES, enables a study intrinsic electronic property materials actual device structures much less influenced by surface condition. With this technique, requirements for preparation are greatly reduced, if not eliminated. It nondestructive tool determine...
The reasoning capabilities of advanced large language models (LLMs) like o1 have revolutionized artificial intelligence applications. Nevertheless, evaluating and optimizing complex processes remain significant challenges due to diverse policy distributions the inherent limitations human effort accuracy. In this paper, we present AURORA, a novel automated framework for training universal process reward (PRMs) using ensemble prompting reverse verification. employs two-phase approach: First,...
ZnO films on c-sapphire with and without an MgO buffer were grown by plasma-assisted molecular beam epitaxy. was two dimensionally grown, while three dimensionally, which confirmed in situ RHEED (reflection high energy electron diffraction) AFM (atomic force microscopy) observations. Morphology evolution growth mechanism of studied Mosaicity (tilt twist angle), type density dislocation both TEM (transmission HRXRD (high resolution x-ray diffraction). Based observations, involves important...
The first self aligned accumulation-mode GaAs MIS-like FET having an n+ -GaAs/undoped GaAlAs/undoped structure is reported. FETs fabricated show the threshold voltage of almost zero (V̅th = 0.035 V) and very uniform (σVth 0.013 characteristics, as expected. transconductance high 170 mS/mm, which highest value ever reported on FETs.
N-type ZnTe layers with high electron concentration are grown by molecular-beam epitaxy using aluminum as the donor species. The ZnTe:Al show a structural quality narrow x-ray diffraction linewidth (24 arcsec) and carrier up to n=4×1018 cm−3 low resistivity (ρ=0.017 Ω cm). dependence of mobility on suggests that dominant scattering mechanisms in ionized impurity polar optical phonon scattering. photoluminescence spectrum moderately doped shows strong Al–donor-related bound exciton lines: I2...
We have measured emission spectra under selective excitation and time resolved photoluminescence of a single crystal with perovskite type structure ${(\mathrm{C}{\mathrm{H}}_{3}{\mathrm{C}}_{6}{\mathrm{H}}_{4}\mathrm{C}{\mathrm{H}}_{2}\mathrm{N}{\mathrm{H}}_{3})}_{2}\mathrm{Pb}{\mathrm{Br}}_{4}$ at low temperature, clarified that triplet excitons generated in the PbBr monolayer are recombined after localization random potential. The localized exciton has lifetime below...
We have investigated electron-trap centers in ZnO layers grown under different Zn∕O flux ratios by molecular-beam epitaxy. Frequency-dependent capacitance measurements show that Zn-rich and stoichiometric conditions suffer from larger dispersion than a layer an O-rich condition. Temperature-dependent reveal all the shallow ET1 deep ET2, while has another center ET3 besides ET2: thermal activation energies of ET1, are estimated to be 0.033–0.046, 0.12–0.15, 0.065 eV, respectively. Moreover,...
We report on the lattice relaxation mechanism of ZnO films grown c-Al2O3 substrates by plasma-assisted molecular-beam epitaxy. The with various thicknesses up to 2000nm is investigated using both in situ time-resolved reflection high energy electron diffraction observation during initial growth and absolute constant measurements (Bond method) for films. residual strain explained terms misfit (compression) at temperature thermal stress (tension) due difference measurement temperatures. In...
This letter presents a reliable and very easy method for selective growth of polarity controlled ZnO films on (0001) Al2O3 substrates by plasma-assisted molecular-beam epitaxy. Cr-compound intermediate layers are used to control the crystal Al2O3. grown rocksalt structure CrN/(0001) shows Zn polarity, while those rhombohedral Cr2O3∕(0001) O polarity. Possible interface atomic arrangements both heterostructures proposed.