InGaN/GaN-multiple-quantum-well-based light emitting diode (LED) nanopillar arrays with a diameter of approximately 200 nm and height 700 are fabricated by inductively coupled plasma etching using Ni self-assembled nanodots as mask. In comparison to the as-grown LED sample an enhancement factor four photoluminescence (PL) intensity is achieved after fabrication nanopillars, blue shift decrease full width at half maximum PL peak observed. The method additional wet different chemical solutions...

The leakage current of GaN Schottky barrier ultraviolet photodetectors is investigated. It found that the adopting undoped instead lightly Si-doped as an active layer show a much lower even when they have higher dislocation density. also density Ga vacancies in than GaN. may enhance tunneling and reduce effective height, leading to increase current. suggests used layer, it necessary photodetector.

The influences of dislocation density and carbon impurities in i-GaN layer on the performance Schottky barrier ultraviolet photodetectors are investigated. It is found that an increase leads to a decrease responsivity, mainly because defects act as charge traps GaN which can recombination probability photo-generated electron-hole pairs. On other hand, it shown high impurity content also causes fact carriers can't be effectively collected due effect C-induced deep level centers related...

The photoluminescence (PL) of CdSexS1-x semiconductor quantum dots (QDs) in a glass spherical microcavity is investigated. clusters embedded matrix are fabricated by using the heat treatment method. Periodical structures consisting sharp spectral lines observed PL spectra CdSexS1-xQDs, which can be well explained coupling with whispering gallery modes based on Mie scattering theory.

High-quality and nearly crack-free GaN epitaxial layer was obtained by inserting a single AlGaN interlayer between epilayer high-temperature AlN buffer on Si (111) substrate metalorganic chemical vapor deposition. This paper investigates the effect of structural properties resulting epilayer. It confirms from optical microscopy Raman scattering spectroscopy that has remarkable introducing relative compressive strain to top preventing formation cracks. X-ray diffraction transmission electron...

A method for accurate determination of the curvature radius semiconductor thin films is proposed. The curvature-induced broadening x-ray rocking curve (XRC) a heteroepitaxially grown layer can be determined if dependence full width at half maximum (FWHM) XRC measured as function incident beam. It found that radii two GaN on sapphire wafer are different when they under similar MOCVD conditions but have values thickness. At same time, dislocation-induced and thus dislocation density epitaxial...

InGaN/GaN multi-quantum-well-structure laser diodes with an array structure are successfully fabricated on sapphire substrates. The diode consists of four emitter stripes which share common electrodes one chip. An 800-μm-long cavity is formed by cleaving the substrate along (1100) orientation using scriber. threshold current and voltage 2 A 10.5 V, respectively. light output peak power 12 W under pulsed injection at room temperature achieved. We simulate electric properties GaN based in a...

This paper investigates the major structural parameters, such as crystal quality and strain state of (001)-oriented GaN thin films grown on sapphire substrates by metalorganic chemical vapour deposition, using an in-plane grazing incidence x-ray diffraction technique. The results are analysed compared with a complementary out-of-plane twist mosaic structure is determined through direct measurement (100) reflection which agrees well result obtained extrapolation method. method for directly...

Room temperature photoreflectance were made on a selectively doped GaAs/n-AlxGa1-xAs two-dimensional electron gas grown by molecular beam epitaxy (MBE). The lineshapes can be fit Aspnes' theory, and the results explained with simple model.

GaN intermedial layers grown under different pressures are inserted between epilayers and AlN/Si(111) substrates. In situ optical reflectivity measurements show that a transition from the three-dimensional (3D) mode to 2D one occurs during epilayer growth when higher pressure is used preceding layer growth, an improvement of crystalline quality will be made. Combining in transmission electron microscopy (TEM) measurements, it suggested lateral at favourable for bending dislocation lines,...

The composition and stain distributions in the InGaN epitaxial films are jointly measured by employing various x-ray diffraction (XRD) techniques, including out-of-plane XRD at special planes, in-plane grazing incidence XRD, reciprocal space mapping (RSM). It is confirmed that measurement of (204) reflection allows a rapid access to estimate without considering influence biaxial strain. two-dimensional RSM checks degree strain relaxation jointly, revealing an inhomogeneous distribution...

To form low-resistance Ohmic contact to p-type GaN, InGaN/GaN multiple quantum well light emitting diode wafers are treated with boiled aqua regia prior Ni/Au (5 nm/5 nm) film deposition. The surface morphology of and the current–voltage characteristics fabricated devices investigated. It is shown that treatment could effectively remove oxide from p-GaN layer, reveal defect-pits whose density almost same as screw dislocation estimated by x-ray rocking curve measurement. suggests metal atoms...

We report our recent progress of investigations on InGaN-based blue-violet laser diodes (LDs). The room-temperature (RT) cw operation lifetime LDs has extended to longer than 15.6 h. LD structure was grown a c-plane free-standing (FS) GaN substrate by metal organic chemical vapor deposition (MOCVD). typical threshold current and voltage under RT are 78 mA 6.8 V, respectively. experimental analysis degradation performances suggests that after aging treatment, the increase series resistance...

A violet laser diode (LD) structure is grown on a free-standing c-plane GaN substrate and 4 μm×800 μm ridge waveguide LDs are fabricated. The electrical the optical characteristics of under different facet-coating chip-mounting conditions investigated pulse mode operation. active region temperatures p-side up down mounted calculated with injection currents. thermal resistances 4.6 K/W 3 K/W, respectively. threshold current LD much lower than that LD. blue shift emission wavelength increasing...

Optical properties of highly strained GaInAs/GaAs quantum wells (QWs) grown by molecular beam epitaxy with Sb assistance are investigated. The samples incorporation and pre-deposition methods display high room-temperature photoluminescence (PL) intensity at extended long wavelength. This result is explained the surfactant effects during growth QW systems. An abnormal S-shaped temperature dependence PL peak position found in In0.42Ga0.58As/GaAs triple QWs sample pre-deposition. By...

The leakage mechanism of GaN-based p-i-n （p-AlGaN/i-GaN/n-GaN） UV detector has been investigated. With the same dislocation density, devices made from material with higher density V-pits on surface produce larger current. SEM images show that some penetrate into i-GaN layer, sometimes even n-GaN layer. If p-ohmic contact metal （Ni/Au） deposits in V-pits, Schottky would be formed at interface and i-GaN, or form ohmic n-GaN. existence parallel junction resistance enhances current greatly.

We present the growth of GaN epilayer on Si (111) substrate with a single AlGaN interlayer sandwiched between and AlN buffer layer by using metalorganic chemical vapour deposition. The influence thickness structural properties has been investigated scanning electron microscopy, atomic force optical microscopy high-resolution x-ray diffraction. It is found that an appropriate plays important role in increasing compressive strain improving crystal quality during interlayer, which can introduce...

Room-temperature operation of cw GaN based multi-quantum-well laser diodes (LDs) is demonstrated. The LD structure grown on a sapphire (0001) substrate by metalorganic chemical vapour deposition. A 2.5μm × 800μm ridge waveguide fabricated. electrical and optical characteristics the diode under direct current injection at room temperature are investigated. threshold voltage 110 mA 10.5 V, respectively. Thermal induced series resistance decrease emission wavelength red-shift observed as...

Properties of the Ag/Ni/p-GaN structure at different temperatures are studied by Auger electron spectroscopy, scanning microscopy and high resolution x-ray diffraction. The effect Ag in ohmic contact on crystalline quality is investigated optimized value annealing temperature reported. lowest specific resistance 2.5×10−4 Ωcm2 obtained 550°C.

Photoluminescence (PL) spectra of GaInNAs/GaAs multiple quantum wells grown on a GaAs substrate by molecular beam epitaxy are measured in range temperatures and excitation power densities. The energy position the dominant PL peak shows an anomalous S-shape temperature dependence instead Varshni relation. By careful inspection, especially for under lower density, two near band-edge peaks well identified. These assigned to carriers localized nitrogen-induced bound states interband excitonic...

Mg-doped p-InGaN layers with In composition of about 10% are grown by metalorganic chemical vapor deposition (MOCVD). The effect the annealing temperature on p-type behavior InGaN is studied. It found that hole concentration in increases a rising range 600–850°C, while mobility remains nearly unchanged until up to 750°C, after which it decreases. On basis conductive growth, p-In0.1Ga0.9N/i-In0.1Ga0.9N/n-GaN junction structure and fabricated into photodiodes. spectral responsivity InGaN/GaN...