Time—Resolved Photoluminescence Studies of AlInGaN Alloys

We study the two samples of AlInGaN,i.e.,1-μm Gan grown at 1030℃ on the buffer and followed by a 0.6μm-thick epilayer of AlInGaN under the low pressure of 76 Torr and the AlInGaN layer deposited diectly on the buffer layer without the high-temperature GaN layer,by temperature-dependent photoluminescence(PL) spectroscopy and picosecond time-resolved photoluminescence(TRPL) spectroscopy.The TRPL signals of both the samples were fitted well as a stretched exponential decay at all temperatures,indicating significant disorder in the material.We attribute the disorder to nanoscale quantum dots or discs of high indium concentration.Temperature dependence of dispersive exponent β shows that the stretched exponential decay of the two samples comes from dfferent mechanisms.The different depths of the localization potential account for the difference,which is illustrated by the results of temperature dependence of radiative recombination lifetime and PL peak energy.     

Modified Photoluminescence by Silicon-Based One-Dimensional Photonic Crystal Microcavities

photoluminescence (PL) lrom one-dimensional photonic band structures is investigated. The doped photonic crystal with microcavitles are fabricated by using alternating hydrogenated amorphous silicon nitride (a-SiNx:H/a-SiNy:H) layers in a plasma enhanced chemical vapour deposition (PECVD) chamber. It is observed that microcavities strongly modify the PL spectra from active hydrogenated amorphous silicon nitride (a-SiNx:H) thin film. By comparison, the wide emission band width 208nm is strongly narrowed to 11 nm, and the resonant enhancement of the peak PL intensity is about two orders of magnitude with respect to the emission of the λ/2-thick layer of a-SiNx:H. A linewidth of Δλ=11 nm and a quality factor of Q=69 are achieved in our one-dimensional a-SiNz photonic crystal microcavities. Measurements of transmittance spectra of the as-grown samples show that the transmittance resonant peak of a cavity mode at 710nm is introduced into the band gap of one-dimensional photonic crystal distributed Bragg reflector (DBR), which further verifies the microcavity effects.     

薄膜物理及其应用讲座：第三讲 非晶半导体薄膜最新进展

介绍了非晶半导体薄膜的结构特点和在光电器件上的独特性能，给出了薄膜器件的发展水平和制膜技术、制膜设备的研究现状。     

退火a—Ge／Pb叠层膜的扩散机制与电阻率的反常行为

研究了a-Ge/Pb叠层膜不同温度下退火的行为,得到:PB诱导a-Ge晶化;发现a-Ge/Pb叠层膜在退火互扩散过程中存在两种扩散机制;对a-Ge/Pb为200nm/100nm的叠层膜,在退火互扩散中择优取向的Pb膜出现重新结晶。解释了退火过程中叠层膜电阻率的反常行为。     

半导体激光器在光谱研究中的应用

近年来半导体激光器的发展引人注目，已由红外波段推向可见光区，可靠性和输出功率提高而价格下降，在光谱研究方面的应用也日益广泛。文章介绍了半导体激光器的现状，频率稳定、压缩线宽和调谐波长的方法，以及半导体激光器在吸收光谱、非线性光谱、原子的冷却和光泵浦原子钟等方面的应用。     

RELAXATION TIME LIMITS PROBLEM FOR HYDRODYNAMIC MODELS IN SEMICONDUCTOR SCIENCE

In this article, two relaxation time limits, namely, the momentum relaxation time limit and the energy relaxation time limit are considered. By the compactness argument, it is obtained that the smooth solutions of the multidimensional nonisentropic Euler-Poisson problem converge to the solutions of an energy transport model or a drift diffusion model, respectively, with respect to different time scales.     

非晶态硒化镉薄膜瞬态光电特性

本文报道用真空热蒸发法淀积的非晶态硒化镉薄膜作光敏介质制备超快光电导探测器。用对撞脉冲锁模Nd:YAG激光器产生的超短光脉冲序列对探测器的响应时间进行检测,结果表明a-CdSe薄膜对皮秒(10^-12秒)级的超短光脉冲作用具有良好的瞬态响应光电特性,探讨a-CdSe薄膜快速弛豫过程的内在机理。     

极性晶体内表面电子的量子像势及其极化子的有效势

本文从与真空接触的存在二支声子的半无限极性晶体表面附近极化子的哈密顿算符入手，应用二支模型理论，分别对GaAs和ZnO两种材料计算了内表面电子的量子像势及其极化子的有效势。计算结果表明：当Z很小时，经典像势和半经典有效势分别与量子像势和量子有效势相差较大；当Z很大时，经典像势和半经典有效势分别是量子像势和量子有效势的一个很好的近似。     

皮秒扫描相机在半导体激光管输出特性研究中的应用

本工作用Picotron 200型扫描相机和液态氮冷却的CCD摄相机系统对半导体激光二极管LTO22 MC的输出特性进行了测量,其最短输出脉冲宽度为2.1ps。这种半导体激光二极管的发射波长为780nm,连续工作条件下,其输出功率为3mW到5mW。