High quality crack-free GaN layers were successfully grown and the InGaN/GaN based blue LEDs
fabricated on patterned Si (111) substrates. In addition to using the patterned growth technique, thin AlN and SiNx
interlayers grown at high temperatures were also employed to partially release the residual stress and to further
improve the crystalline quality. 300 µm square blue LEDs fabricated on the islands, without thinning and package,
exhibited a high output power of around 0.68 mW at a drive current of 20 mA.
The AlGaAs/GaAs double quantum well semiconductor lasers grown by molecular beam epitaxy show high
external quantum efficiency and high power conversion efficiency at continuous-wave power output using an
asymmetric structure. The threshold current density and slope efficiency of the device are 200A/cm<sup>2</sup> and 1.25W/A,
respectively. The high external quantum efficiency and maximum conversion efficiency are 81% and 66%, respectively.
The GaSb characteristics grown by molecular beam epitaxy (MBE) on GaAs substrates was reported. The abruptness of the interfaces, the degree of intermixing and the anion incorporation greatly affect the material quality. The RHEED patterns provide information on the surface structure and morphology of the sample and dictate surface reconstruction, accumulation and segregation. The structure parameters of samples are obtained from the rocking curve. The first and second satellite peaks appear around the main 0th-order peak. The experimental and simulated results of samples A and B with x-ray rocking curves show there is a GaAsSb layer because of As-for-Sb exchange at the GaSb/GaAs interface.
In this paper, we report on structure design of high-power InGaAs/AlGaAs/GaAs fold cavity surface-emitting laser (FCSEL) with 45 degree(s) intracavity micro-mirror. The epitaxial material for these devices was grown by molecular beam epitaxy (MBE) technique. Optical and structural characteristic of the film was studied by photoluminescence (PL), X-ray double crystal diffraction and electrochemical C-V profiling method. The radition wave length 0.921um of sample is obtained at low temperature (10K) PL spectrum. The results of X-ray double crystal rocking curve and low temperature (10K) PL experimental show the structure design of folded cavity surface-emitting lasers is realized By MBE.
In this paper ,high quality AlGaAs/GaAs single quantum well(SQM) structure is grown on (100) GaAs substrate by molecular beam epitaxy (MBE) system. Optical and structural characteristic of the film was studied by low temperature (10K) photoluminescence (PL) and X-ray double crystal diffraction method. Using X-ray kinematical theory, we calculated the structure parameters of each samples, the reason for the appearance of the interfering fringes and splitting peaks in double crystal rocking curve were analyse theoretically. The deep levels which affect character of the material and laser are also discussed. The experimental results show that measuring methods of the photoluminescence and X-ray double crystal diffraction are very important for testing the quality of quantum wells and improving the MBE technology.
GaAlAs/GaAs hetero-epitaxial thin films are prepared by liquid phase epitaxy (LPE) technique. Structural characteristic of the film was Studied by X-ray double crystal rocking curve method. We have measured the rocking curve of (400) reflection and observed the interference fringes. Computer simulation of the experimental curves have been performed with kinematical and dynamical diffraction theory, respectively. We discussed the reason for the appearance of the interference fringe, and calculated structure parameters. The results obtained using dynamical theory is closer to the actual growth parameters.
In this paper we will report GaAlAs/GaAs gradient refraction index separate confinement quantum wells structures by MOCVD growth and its optical properties. The sample were characterized by high-resolution photoluminescence measurements. For 8 nm single quantum well, the excitation luminescence spectra at 10 K are characterized by transitions which has a linewidth (FWHM) of 6.2 nm and large intensity, indicating abrupt GaAlAs/GaAs interface. The shift of X(e-hh) peak position versus the excitation level are also observed. The results of PL measurement show that sample quality has met the requirement of design and proven to be satisfactory.
In the present work, the structure characteristics on InGaAs-GaAs/GaAs strained-layer superlattice (SLS) samples have been studied by measuring x-ray double crystal rocking curve in the non-paralle (+.-) setting and photoluminescence (PL), respectively. Using x-ray kinematical theory, we have calculated structure parameters of SLS and discussed the influence of different substrates. Computer simulation of experimental curve have been performed with kinematical diffraction theory. The experimental and simulated curves are basically identical. Reliability of calculated results using x-ray double rocking curve is further confined by PL.
The measuring conditions of the thickness of thin films with grazing incident x-ray is explained, and interferential principle and method to measure the thickness of thin films by grazing incident x-ray are discussed and analyzed in the paper. The periodic thickness of the multilayer optical thin films is measured with double-crystal diffractometer at a very small grazing incident angle, the result is satisfactory and measured values is in good agreement with designed values.
ZnTe/CdZnTe multiple quantum wells (MQWs) optical bistable device has been fabricated, and optical bistability in ZnTe/CdZnTe MQWs optical bistable device is investigated on transmission at room temperature. The research result indicates that the threshold and contrast ratio for the optical bistability in Zn-Te/CdZnTe MQWs optical bistable device are about 363 kW/cm<SUP>2</SUP> and 4:1, respectively. On the basis of the excitonic nonlinear theories, excitonic absorption spectrum in the ZnTe/CdZnTe MQWs obtained here, we attribute the major nonlinear mechanism for the optical bistability to the saturating effect of excitonic absorption.