78 research outputs found
An enhanced surface passivation effect in InGaN/GaN disk-in-nanowire light emitting diodes for mitigating Shockley-Read-Hall recombination
We present a detailed study of the effects of dangling bond passivation and the comparison of different sulfide passivation processes on the properties of InGaN/GaN quantum-disk (Qdisk)-in-nanowire based light emitting diodes (NW-LEDs). Our results demonstrated the first organic sulfide passivation process for nitride nanowires (NWs). The results from Raman spectroscopy, photoluminescence (PL) measurements, and X-ray photoelectron spectroscopy (XPS) showed that octadecylthiol (ODT) effectively passivated the surface states, and altered the surface dynamic charge, and thereby recovered the band-edge emission. The effectiveness of the process with passivation duration was also studied. Moreover, we also compared the electro-optical performance of NW-LEDs emitting at green wavelength before and after ODT passivation. We have shown that the Shockley–Read–Hall (SRH) non-radiative recombination of NW-LEDs can be greatly reduced after passivation by ODT, which led to a much faster increasing trend of quantum efficiency and higher peak efficiency. Our results highlighted the possibility of employing this technique to further design and produce high performance NW-LEDs and NW-lasers
Initial demonstration of AlGaAs-GaAsP-beta-Ga2O3 n-p-n double heterojunctions
Beta phase gallium oxides, an ultrawide-bandgap semiconductor, has great
potential for future power and RF electronics applications but faces challenges
in bipolar device applications due to the lack of p-type dopants. In this work,
we demonstrate monocrystalline AlGaAs_GaAsP_beta phase gallium oxides n-p-n
double-heterojunctions, synthesized using semiconductor grafting technology. By
transfer printing an n-AlGaAs_p-GaAsP nanomembrane to the n-beta
phase-GaO epitaxial substrate, we simultaneously achieved AlGaAs_GaAsP
epitaxial n-p junction diode with an ideality factor of 1.29 and a
rectification ratio of 2.57E3 at +/- 2 V, and grafted GaAsP_beta_phase_gallium
oxides p-n junction diode exhibiting an ideality factor of 1.36 and a
rectification ratio of 4.85E2 at +/- 2 V.Comment: 12 pages, 4 figure
Demonstration of a monocrystalline GaAs--GaO p-n heterojunction
In this work, we report the fabrication and characterizations of a
monocrystalline GaAs/-GaO p-n heterojunction by employing
semiconductor grafting technology. The heterojunction was created by lifting
off and transfer printing a p-type GaAs single crystal nanomembrane to an
AlO-coated n-type-GaO epitaxial substrate. The resultant
heterojunction diodes exhibit remarkable performance metrics, including an
ideality factor of 1.23, a high rectification ratio of 8.04E9 at +/- 4V, and a
turn on voltage of 2.35 V. Furthermore, at +5 V, the diode displays a large
current density of 2500 A/cm along with a low ON resistance of 2
mcm.Comment: 14 pages, 5 figure
Monocrystalline Si/-GaO p-n heterojunction diodes fabricated via grafting
The -GaO has exceptional electronic properties with vast
potential in power and RF electronics. Despite the excellent demonstrations of
high-performance unipolar devices, the lack of p-type doping in
-GaO has hindered the development of GaO-based bipolar
devices. The approach of p-n diodes formed by polycrystalline p-type oxides
with n-type -GaO can face severe challenges in further advancing
the -GaO bipolar devices due to their unfavorable band alignment
and the poor p-type oxide crystal quality. In this work, we applied the
semiconductor grafting approach to fabricate monocrystalline
Si/-GaO p-n diodes for the first time. With enhanced
concentration of oxygen atoms at the interface of Si/-GaO,
double side surface passivation was achieved for both Si and
-GaO with an interface Dit value of 1-3 x 1012 /cm2 eV. A
Si/-GaO p-n diode array with high fabrication yield was
demonstrated along with a diode rectification of 1.3 x 107 at +/- 2 V, a diode
ideality factor of 1.13 and avalanche reverse breakdown characteristics. The
diodes C-V shows frequency dispersion-free characteristics from 10 kHz to 2
MHz. Our work has set the foundation toward future development of
-GaO-based transistors.Comment: 32 pages, 10 figures. The preliminary data were presented as a poster
in the 5th US Gallium Oxide Workshop, Washington, DC. August 07-10, 202
Electron cyclotron resonance (ECR) plasma etching study of GaAs and GaInP
This thesis presents the Electron Cyclotron Resonance (ECR) plasma etching of GaAs and Ga(0.52)In(0.48)P grown using Solid Source Molecular Beam Epitaxy (SSMBE) with a view of applying the process for future heterojunction bipolar transistors (HBTs) fabrication.Master of Engineerin
Molecular beam epitaxial growth of GaNAs and GaInNAs and their characterization
This thesis presents the systematic growth and characterization studies of the GaInNAs/GaAs Quantum Well (QW) and related GaNAs bulk material by Molecular Beam Epitaxy (MBE) technique. The motivation of this work lies in the significant advantage in growing optoelectronic devices on GaAs substrate compared to InP substrate. The availability of N plasma source and MBE ensure the incorporation of sufficient N in the GaInNAs material. They also make low temperature growth possible, which is essential for reducing phase separation in the material. As-grown and annealed GaInNAs/GaAs QWs were characterized by Photoluminescence (PL), Time-Resolved Photoluminescence (TR-PL), and X-Ray Diffraction (XRD) to examine their optical and structural quality. The integrity of the GaAs cap layer grown on the QW samples and annealed by Rapid Thermal Annealing (RTA) equipment was confirmed by Atomic Force Microscopy (AFM).DOCTOR OF PHILOSOPHY (EEE
Spectral Analysis of Quantum-Dash Lasers: Effect of Inhomogeneous Broadening of the Active-Gain Region
Two-step controllable electrochemical etching of tungsten scanning probe microscopy tips
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