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MOCVD生长GaN:Si单晶膜的研究 总被引:4,自引:0,他引:4
获得高质量的n型GaN单晶膜是制作GaN基光电子器件的关键之一。采用立式MOCVD系统生长GaN:Si单晶膜,通过优化生长工艺,获得了电子载流于浓度高达2 ×1019cm-3,迁移率达120cm2/V·s的n型GaN:Si单晶膜;并有效地抑制了GaN中由深能级引起的黄带发射,大大提高带边发光强度。研究结果还表明:随着S掺杂量的增大,GaN:Si单晶膜的电子载流于浓度增加,迁移率下降,X光双晶衍射峰半高宽增大。首次报道了随掺S量增大,GaN:Si单晶膜的生长速率显著下降的现象。 相似文献
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采用MOCVD技术在Al2O3(0001)衬底上生长了GaN薄膜,使用透射光谱、光致发光光谱和X射线双晶衍射三种技术测试了五类GaN薄膜样品,实验结果表明:GaN薄膜透射谱反映出的GaN质量与X射线双晶衍射测量的结果一致,即透射率越大,半高宽越小,结晶质量越好;而X射线双晶衍射峰半高宽最小的样品,其PL谱的带边峰却很弱,这说明PL谱反映样品的光学性能与X射线双晶衍射获得的结晶质量不存在简单的对应关系,同时还报导了一种特殊工艺生长的高阻GaN样品的RBS/沟道结果。 相似文献
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垂直腔面发射激光器的结构生长及特性研究 总被引:1,自引:1,他引:0
在偏〈111〉A 2°的GaAs (100) 衬底上生长了Al0.9Ga0.1As /Al0.2Ga0.8As周期结构的垂直腔面发射激光器(VCSEL)外延片P 型DBR的周期数为24.5对,N型DBR的周期数为34.5对.用光荧光 (PL) 谱、扫描电子显微镜 (SEM)和X射线双晶衍射 (XRD) 方法对VCSEL的光学特性和结构特性进行了分析室温量子阱材料的PL谱峰值波长为837.0 nm,半高宽达到28.9 nm在X射线双晶衍射回摆曲线中,除了“0”级衍射峰外,还观察到一级和二级卫星峰.“0”级双晶衍射峰的半高宽为12.56弧秒(″),衬底GaAs的衍射峰半高宽为11.79″.“0”级衍射峰半高宽与衬底GaAs的衍射峰半高宽比较接近,表明晶格具有很高的完整性.实验结果表明腔模波长为837.2 nm,腔模波长与PL谱峰值波长相匹配. 相似文献
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高质量GaN外延薄膜的生长 总被引:1,自引:0,他引:1
综述了高质量GaN外延薄膜的生长研究工作的最新重要进展.主要采用的新工艺为:在较低温度下生长GaN缓冲层后再高温生长GaN外延薄膜,双气流金属有机化合物气相沉积(MOCVD),以及用开有窗口的SiO2膜截断穿过位错后横向覆盖外延生长(epitaxialylateralovergrowth).X射线衍射和高分辨电镜研究证实,上述工艺使GaN外延薄膜质量得到显著提高.利用这种薄膜研制成的蓝色激光管即将投放市场. 相似文献
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GaAlAs/GaAs量子阱结构的实验研究 总被引:1,自引:0,他引:1
利用分子束外延生长法生长出了GaAlAs/GaAs梯度折射率分别限制单量子阱结构材料,对样品进行了光荧光谱、双晶X射线衍射和电化学电容-电压分布测量。实验结果表明,样品质量达到了设计要求,利用该材料制作的激光二极管获得了初步结果。 相似文献
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综合介绍了高分辨X射线双晶衍射技术、三轴晶衍射技术及掠入射衍射和全反射技术.着重介绍了这些技术应用于低维材料微结构探测所取得的新进展. 相似文献
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Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide 总被引:1,自引:0,他引:1
Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs. 相似文献
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A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output. 相似文献
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S. G. Nedel’ko M. A. Krysyuk A. L. Apanasenko L. N. Lymarenko Z. T. Moroz 《Journal of Applied Spectroscopy》1997,64(1):55-61
Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped
with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly
described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation
(5.5·104 Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum
cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics
of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure
crystals is analyzed (preliminarily).
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997. 相似文献
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The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper. 相似文献
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A multi-conjugate adaptive optics (MCAO) can offer a possibility of widening field of view (FOV) characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle's expressions of two deformable mirrors (DMs) MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance. 相似文献
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Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use. 相似文献
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We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed. 相似文献
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Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell. 相似文献