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从Ⅲ-Ⅴ族氮化物半导体压电极化对应变的依赖关系出发,采用有限元方法计算了GaN/AIN量子点结构中的应变分布,研究了其自发极化、压电极化以及极化电荷密度.结果表明,应变导致的压电极化和Ⅲ-Ⅴ族氮化物半导体所特有的自发极化将导致电荷分布的变化,使电子聚集在量子点顶部,空穴聚集在量子点下面的湿润层中,在量子点结构中产生显著的极化电场,并讨论了电场的存在对能带带边的形状以及能级分布的影响. 相似文献
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研究了AlGaN/GaN异质结构上的肖特基接触的基本原理及载流子的高温输运特性.将AlGaN/GaN异质结SBD和AlGaN SBD,在27~250℃进行实验比较.发现随着温度上升,AlGaN SBD的势垒高度下降,理想因子增加,其影响因素包括热电子发射、场发射、隧穿效应及复合电流效应等机制.而AlGaN/GaN异质结SBD由于受到压电极化场和2DEG和的影响,其势垒高度和理想因子随温度的变化趋势与AlGaNSBD相反.实验结果还显示,AlGaN/GaN异质结SBD的反向电流随着温度的上升,呈现先增大后减小的趋势. 相似文献
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从Ⅲ-Ⅴ族氮化物半导体压电极化对应变的依赖关系出发,采用有限元方法计算了GaN/AlN量子点结构中的应变分布,研究了其自发极化、压电极化以及极化电荷密度.结果表明,应变导致的压电极化和Ⅲ-Ⅴ族氮化物半导体所特有的自发极化将导致电荷分布的变化,使电子聚集在量子点顶部,空穴聚集在量子点下面的湿润层中,在量子点结构中产生显著的极化电场,并讨论了电场的存在对能带带边的形状以及能级分布的影响. 相似文献
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从Ⅲ-Ⅴ族氮化物半导体压电极化对应变的依赖关系出发,采用有限元方法计算了GaN/AlN量子点结构中的应变分布,研究了其自发极化、压电极化以及极化电荷密度.结果表明,应变导致的压电极化和Ⅲ-Ⅴ族氮化物半导体所特有的自发极化将导致电荷分布的变化,使电子聚集在量子点顶部,空穴聚集在量子点下面的湿润层中,在量子点结构中产生显著的极化电场,并讨论了电场的存在对能带带边的形状以及能级分布的影响. 相似文献
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《中国无线电电子学文摘》2007,(6)
O4712007060630GaN/AlN量子点结构中的应变分布和压电效应/梁双,吕燕伍(北京交通大学物理系)//半导体学报.―2007,28(1).―42~46.从Ⅲ-Ⅴ族氮化物半导体压电极化对应变的依赖关系出发,采用有限元方法计算了GaN/AlN量子点结构中的应变分布,研究了其自发极化、压电极化以及极化电荷密度。结果表明,应变导致的压电极化和Ⅲ-Ⅴ族氮化物半导体所特有的自发极化将导致电荷分布的变化,使电子聚集在量子点顶部,空穴聚集在量子点下面的湿润层中,在量子点结构中产生显著的极化电场,并讨论了电场的存在对能带带边的形状以及能级分布的影响。图4表1… 相似文献
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文章基于挠曲电和应变梯度效应的共同影响,建立了静拉伸下一维压电半导体力电耦合计算模型,数值分析了挠曲电和应变梯度效应对位移、电势、电位移、载流子分布等物理场的影响。结果表明:两种效应对机械位移场没有影响,但对各电相关物理场的分布影响显著;挠曲电效应对压电结构本身的压电性能有抑制作用,而应变梯度效应却增强了其压电特性。本研究为压电类微纳结构的机电特性分析提供了理论指导。 相似文献
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采用k·p方法理论,考虑了极化电场和自由载流子重新分布等因素,通过薛定谔方程和泊松方程自洽求解得到InGaN/AlInGaN,InGaN/GaN,InGaN/InGaN,InGaN/AlGaN量子阱导带和价带的能带结构,并由此计算了不同量子阱结构的自发发射谱.分析对比发现AlInGaN材料特有的自发极化和压电极化效应在阱垒界面处形成的极化电荷对量子阱发光特性有重要的影响.以AlInGaN为垒,优化其中各元素的组分可以减小极化电场的影响,提高量子阱自发发射谱强度.同时,综合考虑了极化电荷和势垒高度的影响,提出了具体的优化方法,并给予了物理解释. 相似文献
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采用k·p方法理论,考虑了极化电场和自由载流子重新分布等因素,通过薛定谔方程和泊松方程自洽求解得到InGaN/AlInGaN,InGaN/GaN,InGaN/InGaN,InGaN/AlGaN量子阱导带和价带的能带结构,并由此计算了不同量子阱结构的自发发射谱.分析对比发现AlInGaN材料特有的自发极化和压电极化效应在阱垒界面处形成的极化电荷对量子阱发光特性有重要的影响.以AlInGaN为垒,优化其中各元素的组分可以减小极化电场的影响,提高量子阱自发发射谱强度.同时,综合考虑了极化电荷和势垒高度的影响,提出了具体的优化方法,并给予了物理解释. 相似文献
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微波功率AlGaN/GaN HFET的二维能带和异质结构设计 总被引:1,自引:0,他引:1
薛舫时 《中国电子科学研究院学报》2007,2(5):456-463
在综述微波功率AlGaN/GaN HFET技术发展趋势基础上,提出了二维异质结能带优化设计的新课题.从自洽求解薛定谔方程和泊松方程出发研究了利用异质界面上的极化电荷来剪裁异质结能带.用极化电荷设计近矩形前势垒能增大高能热电子的隧穿势垒宽度,抑制电流崩塌.背势垒中的极化电荷强化了沟道阱的量子限制,减弱了沟道中的强场峰,能提高击穿电压和抑制电流崩塌.薄势垒层中的极化电荷强化了沟道阱的结构,降低势垒高度后能产生高密度的电子气.优化设计二维异质结构能抑制沟道中的强场峰和电流崩塌,提高击穿电压和大漏压下的输出功率. 相似文献
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压电扭转问题中非线性极化分析及电场检测 总被引:5,自引:1,他引:4
应用弹性理论、压电理论分析了压电体内的应力状态及由其所导致的非线性极化状态。由于极化梯度的存在,不仅在压电体的表面上会产生等效面束缚电荷,在压电体内部同时也会有等效体束缚电荷的聚集。以矩形截面石英柱体为例,选取级数形式的应力函数,采用能量法及根据电场的等效原理推导了由扭转而产生的剪应力和面束缚电荷密度及体束缚电荷密度的解析表达式,得到了迥异于线性极化的结果。采用有限元方法计算了束缚电荷产生的电场。建立了机械扭矩同检测电极的输出电量之间的线性关系,并实现了单压电体扭矩检测。 相似文献
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A. T. Paxton A. Sher M. Berding M. Van Schilfgaarde M. W. Muller 《Journal of Electronic Materials》1995,24(5):525-532
Dislocations crossing a junction in HgCdTe have little effect on detector responsivity, but are known to reduce the zero bias
impedance RoA. and increase the leakage current, especially at low temperatures where RoA is dominated by tunneling and generation/recombination processes. We have calculated the Coulomb and piezoelectric fields
associated with dislocations in an attempt to interpret their effect on the junction’s transport properties. Dislocation electric
fields can affect transport since they are superimposed on the built-in and applied junction fields which control the currents.
The screening of the fields in the neutral region is consistent with the dislocations’ small effect on responsivity. Their
impact in the space charge region is found to be significant and consistent with the nonlinear dependence of performance on
dislocation density. The piezoelectric potential of the typical 60° dislocation in a sphalerite crystal, and the Coulomb potential
of a dislocation crossing the junction plane other than normally, are angularly varying in the junction plane. Angular variation
of the potentials can be qualitatively interpreted as an angular modulation of the potential barrier. Because of the nonlinear
dependence of junction currents on the barrier (or the junction potential), the angular variation of the currents does not
vanish upon averaging. We find that the range of the Coulomb potential is too small to account for a major portion of the
experimentally reported performance degradation but may be responsible for the reduction of RoA at cryogenic temperatures and low dislocation density, and that the longer range piezoelectric potential may be important.
We also find that superposing the potentials of neighboring dislocations, because of the nonlinear dependence of junction
leakage currents on junction potentials may account for the observed nonlinearity of performance degradation with dislocation
density as measured by etch pit density. 相似文献
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Ruomeng Yu Xingfu Wang Wenzhuo Wu Caofeng Pan Yoshio Bando Naoki Fukata Youfan Hu Wenbo Peng Yong Ding Zhong Lin Wang 《Advanced functional materials》2015,25(33):5277-5284
The piezophototronic effect is known as a three‐way coupling between piezoelectric polarization, semiconductor property, and optical excitation in piezoelectric semiconductor materials to modify their energy band structures by strain‐induced piezoelectric polarization charges, and thus to tune/control their optoelectronic processes of charge carrier generation, separation, recombination, and transport. In this work, the temperature dependence of the piezophototronic effect in wurtzite‐structured CdS nanowires is investigated from 77 to 300 K. The piezophototronic effect is enhanced by over 550% under lower temperature due to the increased effective piezoelectric polarization surface/interface charges resulting from the reduced screening effect by decreased mobile charge carriers in CdS nanowires. Optoelectronic performances of CdS nanowires are systematically investigated under various light illuminations, strains, and temperatures. By analyzing the corresponding band diagrams, the piezophototronic effect is found to dominate the transport and separation processes of charge carriers. This study presents in‐depth fundamental understanding about the piezophototronic effect and provides guidance for its future applications in optoelectronic devices. 相似文献
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在最近的实验中,PN结型量子阱结构被观察到反常的载流子输运情况,其相应的物理机制和载流子输运模型被提出。通过系统实验观察到,PN结量子阱结构材料在共振激发模式下,仍可测出开路电压或短路电流。对比开路和短路情况下的光致荧光(PL)光谱,发现短路下PL强度明显降低。这说明短路状态下的光生载流子没有被限制在量子阱内,而是逃逸出结区。这种载流子逃出量子阱的现象却没有在等量偏压下的NN型量子阱结构中发现,说明载流子逃出量子阱并非由传统的热激发或隧穿的作用导致。据此,笔者提出了相应的物理机制和载流子输运模型对此现象进行解释,认为光生载流子能在PN结内建电场的作用下直接逃出量子阱,并且辐射复合发光发生在载流子逃逸过程之后。 相似文献
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A self-consistent approach is used to examine gain and radiative lifetimes in InGaN-GaN quantum-well structures. The effect of high built-in electric fields due to spontaneous polarization and the piezoelectric effect and the screening of these fields by carrier injection is examined. We study how the peak gain and radiative lifetime vary with injection density and well size. We also examine the blue shift in the peak gain energy with carrier injection. Implications for laser design are discussed 相似文献