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Effect of Reactor Pressure on Qualities of GaN Layers Grown by Hydride Vapour Phase Epitaxy 下载免费PDF全文
The influence of reactor pressure on GaN layers grown by hydride vapour phase epitaxy (HVPE) is investigated. By decreasing the reactor pressure from0. 7 to 0.5 mm, the GaN layer growth mode changes from the island-like one to the step flow. The improvements in structural and optical properties and surface morphology of GaN layers are observed in the step flow growth mode. The results clearly indicate that the reactor pressure, similarly to the growth temperature, is One of the important parameters to influence the qualities of GaN epilayers grown by HVPE, due to the change of growth mode. 相似文献
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采用八能带K-P理论以及有限差分方法,研究了沿[001]方向生长的InAs/GaSb二类断带量子阱体系的能带结构、波函数分布和对[110]方向线性偏振光的吸收特性.研究发现,通过改变InAs或GaSb层的厚度,可有效调节该量子阱体系的能带结构及波函数分布.计算结果表明,当InAs/GaSb量子阱的导带底与价带顶处于共振状态时,导带基态与轻空穴基态杂化效应很小,且导带基态与第一激发态的波函数存在较大的重叠,导带基态与第一激发态之间在布里渊区中心处的跃迁概率明显大于导带底与价带顶处于非共振状态时的跃迁概率.研究结果对基于InAs/GaSb二类断带量子阱体系的中远红外波段的新型级联激光器、探测器等光电器件的设计具有重要意义. 相似文献
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通过沟槽结构和可调节的电子势垒,沟槽栅极超势垒整流器可以更为有效地实现通态压降和反向漏电流之间的良好折衷.在高压应用时,电荷耦合效应对于提高该器件的反向承压能力起到了关键作用.本文通过理论模型与器件模拟结果,分析了沟槽深度、栅氧厚度和台面宽度等关键参数对电荷耦合作用下二维电场分布的影响,归纳出了提高该器件击穿电压的思路与方法,为器件设计提供了有意义的指导.在此基础上,提出了阶梯栅氧结构,该结构在维持几乎相同击穿电压的同时,使正向导通压降降低51.49%. 相似文献
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Effect of Ⅲ/Ⅴ Ratio of HT-AIN Buffer Layer on Polarity Selection and Electrical Quality of GaN Films Grown by Radio Frequency Molecular Beam Epitaxy 总被引:1,自引:0,他引:1 下载免费PDF全文
We investigate the effect of A/N ratio of the high temperature (HT) AIN buffer layer on polarity selection and electrical quality of GaN films grown by radio frequency molecular beam epitaxy. The results show that low Al/N ratio results in N-polarity GaN films and intermediate Al/N ratio leads to mixed-polarity GaN films with poor electrical quality. GaN films tend to grow with Ga polarity on Al-rich AIN buffer layers. GaN films with different polarities are confirmed by in-situ reflection high-energy electron diffraction during the growth process. Wet chemical etching, together with atomic force microscopy, also proves the polarity assignments. The optimum value for room-temperature Hall mobility of the Ga-polarity GaN film is 703cm^2/V.s, which is superior to the N-polarity and mixed-polarity GaN films. 相似文献
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Theoretical Analysis of Current Crowding Effect in Metal/AIGaN/GaN Schottky Diodes and Its Reduction by Using Polysilicon in Anode 下载免费PDF全文
There exists a current crowding effect in the anode of AIGaN/GaN heterojunction Schottky diodes, causing local overheating when working at high power density, and undermining their performance. The seriousness of this effect is illustrated by theoretical analysis. A method of reducing this effect is proposed by depositing a polysilicon layer on the Schottky barrier metal. The effectiveness of this method is provided through computer simulation. Power consumption of the polysilicon layer is also calculated and compared to that of the Schottky junction to ensure the applicability of this method. 相似文献
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Inrecentdecades,thephysiologicalfunctionofREEsandtheirsignificanceonlivingbeingsaswellastheirlongtermbiologicaleffectsonbodiesoflivingbeingshavedrawngreatattention.accompaniedbytheextensiveapplicationofREEsinagriculture,modernindustryandmedicine.Howeve… 相似文献
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应用反胶束法制备了稀磁半导体Cd1-xMnxS量子点.量子点的大小可通过改变ωo值(wo=[水]/[表面活性剂])来控制.高分辨透射电镜的分析结果表明,量子点呈单分散性,是几乎没有缺陷的单晶体.量子点的大小约为4.8~6nm,随wo值增大而增大.电子能谱(EDS)测定结果表明,Mn2+离子在量子点中的摩尔分数为1.5%.由电子自旋共振(ESR)分析确定一部分Mn2+离子取代Cd2+离子位置而位于晶格,另一部分Mn2+离子位于Cd1-xMnxS的表面或间隙位置.吸收光谱显示,随着量子点变小,吸收带边发生蓝移,显示明显的量子尺寸效应.光致荧光光谱分析表明,发光峰属于Mn2+的4T1-6A1跃迁,而且随着ωo和粒径的增大,发光峰从2.26,2.10,2.05eV红移到1.88eV;其发光峰偏离2.12eV,主要是由于Mn2+离子位于扭曲的四面体晶体场所致. 相似文献
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采用磁控溅射法制备出透明导电氧化物NiO薄膜.椭偏(SE)测试表明NiO薄膜在可见光区域透光性良好,通过调节生长、退火温度可调控NiO的折射率.采用X射线衍射(XRD)、扫描电子显微镜(SEM)手段研究表明,通过退火、改变衬底温度等,可有效改变NiO薄膜的晶体结构以及表面形貌,实现对NiO导电性的调控. 采用优化后的NiO材料为阳极阻挡层制备出的聚合物太阳能电池器件的效率为2.26%,是同等条件下采用 PEDOT:PSS阻挡层的电池器件的3倍以上. 相似文献