A5045724797- Photonic and Optical Devices
- GaN-based semiconductor devices and materials
- Semiconductor Lasers and Optical Devices
- Semiconductor Quantum Structures and Devices
- ZnO doping and properties
- Ga2O3 and related materials
- Metal and Thin Film Mechanics
- Advanced Photonic Communication Systems
- Nanowire Synthesis and Applications
- Acoustic Wave Resonator Technologies
- Photonic Crystals and Applications
- Semiconductor materials and devices
- Advanced Fiber Optic Sensors
- Advanced MEMS and NEMS Technologies
- Thin-Film Transistor Technologies
- Integrated Circuits and Semiconductor Failure Analysis
- Mechanical and Optical Resonators
- Silicon Carbide Semiconductor Technologies
- Optical Network Technologies
- Silicon Nanostructures and Photoluminescence
- Surface and Thin Film Phenomena
- Thermal properties of materials
- Nanofabrication and Lithography Techniques
- solar cell performance optimization
- Silicon and Solar Cell Technologies
University of Arkansas at Fayetteville
2017-2025
V.E. Lashkaryov Institute of Semiconductor Physics
2013-2022
University of Electronic Science and Technology of China
2017-2020
National Academy of Sciences of Ukraine
2014-2018
Chengdu University
2018
Group IV GeSn double-heterostructure (DHS) lasers offer unique advantages of a direct bandgap and CMOS compatibility. However, further improvements in the laser performance have been bottlenecked by limited junction properties through conventional epitaxy wafer bonding. This work leverages semiconductor grafting to synthesize characterize optically pumped ridge edge-emitting with an AlGaAs nanomembrane transfer-printed onto epitaxially grown substrate, interfaced ultrathin Al2O3 layer. The...
Germanium tin (GeSn) is a tuneable narrow bandgap material, which has shown remarkable promise for the industry of near- and mid-infrared technologies high efficiency photodetectors laser devices.
The instability during the growth and processing of epitaxial GeSn layers with high Sn molar fraction compressive strain is still to be fully studied. In this work, relationship among relief, dislocations, outdiffusion in a content ∼9 atom % was studied as function pre-existing misfit/threading dislocation (MD/TD) density annealing time at 300 °C. For epilayer strained Ge-on-Si virtual substrate (Ge-VS), an increase relief by factor ∼2 observed after 2 h annealing, without significant effect...
The effects of lattice misfit strain in epitaxial GeSn/Ge/Si(001) heterostructures on Sn incorporation, dislocations (MDs), and the critical thickness were investigated using high-resolution x-ray diffraction. By performing a simulation reciprocal space maps measured vicinity an asymmetrical reflection, we determined strong correlation between relaxation, density MDs, content GeSn alloy for compositional range 4 to 15 at. %. Herein, quantitatively describe phenomenon strain-suppressed...
Abstract High-quality monolithic Ge-on-Si is sought for CMOS-compatible optoelectronic devices. We examine the structural characteristics of grown by aspect ratio trapping (ART) method on a SiO 2 /Si(001) template in pre-patterned holes. Transmission electron microscopy and surface topography analysis revealed high-quality Ge islands overgrown from ART holes . The superior crystal quality growth was also confirmed comparing x-ray diffraction (XRD) data planar epilayer samples. XRD...
Ion implantation is widely used in the complementary metal–oxide–semiconductor process, which stimulates to study its role for doping control rapidly emerging group IV Ge1−xSnx materials. We tested impact of As and B subsequent rapid thermal annealing (RTA) on damage formation healing lattice. was done at 30, 40, 150 keV with various doses. The profiles were confirmed using secondary ion mass spectrometry. X-ray diffraction combination Raman photoluminescence spectroscopies indicated notable...
In this work, the influence of micro- and macro-deformation profiles in GaN nanowires (NWs) on angular intensity distribution X-ray diffraction are studied theoretically. The calculations performed by using kinematical theory assuming deformation decays exponentially from NW/substrate interface. Theoretical modeling scattering NWs with different carried out. We show that shape (002) 2θ/ω profile (XDP) is defined initial at NW's bottom its relaxation depth given decay exponential profile....
A new approach is described that applicable for structural characterization of any heteroepitaxially grown (strained or relaxed) III-nitride superlattices (SLs). The proposed method utilizes X-ray reciprocal space mapping measured in the vicinity an asymmetrical reflection to determine SL period, thickness, and strain state a quantum well/barrier. On example GaN/AlN SL, it demonstrated structure parameters obtained from agree very well with revealed by currently preferred based on...
We report on AlxGa1-xN heterostructures resulting from the coherent growth of a positive then negative gradient Al concentration [0001]-oriented GaN substrate. These polarization-doped p-n junction structures were characterized at nanoscale by combination averaging as well depth-resolved experimental techniques including: cross-sectional transmission electron microscopy, high-resolution X-ray diffraction, Rutherford backscattering spectrometry, and scanning probe microscopy. observed that...
Here, we demonstrate X-ray fitting through kinematical simulations of the intensity profiles symmetric reflections for epitaxial compositionally graded layers AlGaN grown by molecular beam epitaxy pseudomorphically on [0001]-oriented GaN substrates. These detailed depict obvious differences between changes in thickness, maximum concentration, and concentration profile layers. Through comparison these with as-grown samples, can reliably determine parameters, most important which are strain...
Superlattices (SLs) consisting of symmetric layers GaN and AlN have been investigated. Detailed X-ray diffraction reflectivity measurements demonstrate that the relaxation built-up strain in films generally increases with an increasing number repetitions; however, apparent for subcritical thickness SLs is explained through accumulation Nagai tilt at each interface SL. Additional atomic force microscopy reveal surface pit densities which appear to correlate amount residual along appearance...
Abstract GeSn-based quantum wells (QWs) are of great interests for the development all-group-IV optoelectronic devices such as lasers. Using a GeSn buffer and SiGeSn barrier has been studied with aim obtaining direct bandgap well increasing carrier confinement. However, collection efficiency configuration remains unsatisfactory. In this work, single QW additional inserted between was grown characterized. Under relatively low injection, photoluminescence results show dramatically enhanced...
The strain relaxation, depth profiles of composition and density dislocations in GeSn epilayers were studied by using the x-ray diffraction. Regions with uniform graded composition, different levels dislocation found layers grown at fixed growth conditions. At initial stage growth, layer is under ∼8 × 10–3 compressive strain, Sn close to target value 6.6%. With increasing thickness, content enhanced 0.85 ± 0.12% due relief down ∼5.0 10–4. plastic relaxation dominated 60° misfit GeSn/Ge...
Ge1−xSnx growth on a new sapphire platform has been demonstrated. This involved the of GeSn Ge/GaAs layers using algorithm developed. The resultant growths Ge GaAs/AlAs/sapphire and Ge/GaAs/AlAs/sapphire were investigated by in situ ex characterization techniques to ascertain surface morphology, crystal structure, quality. mode GaAs was predominantly two-dimensional (2D), which signifies layer-by-layer deposition, contributing enhanced quality system. with 10% Sn graded profile for 30 min...
The development of all-group IV GeSn materials on Si substrates is interest for monolithic midwave infrared (MWIR) silicon photonics. Despite their great potential, the growth high crystalline quality still challenging. conventional films displays densities dislocations and, hence, large dark currents. We have examined a state-of-the-art lithographically defined aspect ratio trapping (ART) approach threading (TDs) filtering in and demonstrated selective holes embedded SiO2/Si(001) template....
Plastic strain relaxation in epitaxial layers is one of the crucial factors that limits performance III-nitride-based heterostructures. In this work, we report on and crystalline defects heterostructures consisting compositionally graded AlGaN tensile-strained between a GaN-buffer GaN-cap. We demonstrate effects Al concentration shape concentration-depth profile buried accumulated elastic energy how influences critical thickness for crack generation or fracture. It shown fracture leads to...
We report the results of a study that was conducted to investigate recombination paths photoexcited charge carriers in GeSn thin films. The carrier lifetime predicted as function temperature from description photoconductivity transients, assuming co-influence Shockley-Read-Hall and radiative paths. identify dislocations are source band electronic states with highest occupied state at E V + (85÷90) meV acts centers determining lifetime. photoluminescence (PL) spectroscopy have been applied...