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根据能带电子输运理论,对光激发热电子的产生、弛豫、复合过程进行了分析,并利用蒙特卡罗方法对不同电场中热电子输运的漂移速度瞬变特性进行了模拟。在稳态条件下,光电导及其相应的光电特性主要决定于复合过程;而在强电场和高激发状态下,则主要决定于热电子的行为。实验选用横向型GaAs光电导开关,在一定的偏置电压条件下输出线性与非线性两种不同模式的电脉冲,实验结果与理论一致。 相似文献
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<正> 一、引言 随着大规模集成电路的发展,器件尺寸不断缩小。在许多器件中,局部电场可以很高,载流子能被显著加速。载流子通过器件的渡越时间可和能量弛豫时间相近,在这种情形下漂移速度过冲不可避免。这时,传统的稳态输运理论不再适用,因为这种理论把速度看作瞬时电场的函数。Monte Carlo方法由于计算量大,目前还难以实际应用于器件模拟。因此,希望发展基于宏观描述的非稳态输运的方法,以节省计算机时间,开发实用化的模拟程序。 相似文献
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报道了分别用三带和全带模型蒙特卡罗方法模拟纤锌矿相GaN体材料输运特性的结果,并对基于两种模型的模拟结果进行了比较.在低场区,基于两种模型获得的输运特性基本相同,但在高场区却表现出明显的差别.这是因为在高场区,电子平均能量较高,多数电子处于能带图中的高能态位置,电子能量与波矢量的关系表现出明显的非椭圆特性.由于三带模型假定了能量与波矢量简单关系,故算得的平均能量,高于由全带蒙特卡罗模拟算得的能量.从而导致其它特性的差别.全带模型包含了基于能带理论算得的能带结构的所有特性,故模拟结果更加精确. 相似文献
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用三带和全带模型蒙特卡罗方法模拟纤锌矿相GaN体材料输运特性结果的比较 总被引:3,自引:0,他引:3
报道了分别用三带和全带模型蒙特卡罗方法模拟纤锌矿相GaN体材料输运特性的结果,并对基于两种模型的模拟结果进行了比较.在低场区,基于两种模型获得的输运特性基本相同,但在高场区却表现出明显的差别.这是因为在高场区,电子平均能量较高,多数电子处于能带图中的高能态位置,电子能量与波矢量的关系表现出明显的非椭圆特性.由于三带模型假定了能量与波矢量简单关系,故算得的平均能量,高于由全带蒙特卡罗模拟算得的能量.从而导致其它特性的差别.全带模型包含了基于能带理论算得的能带结构的所有特性,故模拟结果更加精确. 相似文献
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耦合量子阱和超晶格中的Stark效应及电场感生的局域化 总被引:1,自引:0,他引:1
薛舫时 《固体电子学研究与进展》1990,10(3):262-270
本文使用单带双谷模型和隧道谐振方法计算了电场作用下耦合量子阱和超晶格中的电子态.计算中考虑了能谷的非抛物线性和Г,Х两个能谷的贡献.算得的耦合量子阱能级同实验结果之间吻合良好,并且得出在某些电场下两个阱中的不同能级之间可能产生耦合.对超晶格的计算同样得到了同实验吻合的电场作用下的局域化及电子的带间跃迁能量.在GaAs/AlAs超晶格中还算得了适当电场下的有趣的Г-Х混和现象. 相似文献
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比较研究了InGaAs/GaAs量子链和量子点的稳态和瞬态光学特性.实验发现,量子链的荧光寿命有很强的探测能量依赖关系,而量子点的荧光寿命随能量变化较小;量子链的荧光寿命随着激发功率迅速增加,高功率时趋于饱和,而量子点的荧光寿命随激发功率变化缓慢;此外,量子链样品的荧光上升时间也比量子点的小得多.这些结果清楚表明,在量子链结构中,参与发光的载流子之间存在很强的耦合和输运.进一步分析表明,这种耦合作用主要发生在量子链方向.荧光的偏振特性进一步证实了这一点. 相似文献
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Stephen K. O’Leary Brian E. Foutz Michael S. Shur Lester F. Eastman 《Journal of Electronic Materials》2003,32(5):327-334
We studied the sensitivity of the steady-state electron transport in GaN to variations in the important material parameters
related to the band structure. We found (a) that an increase in the lowest conduction-band-valley effective mass leads to
a lowering and broadening of the peak in the velocity-field characteristic, as well as to an increase in the field at which
the peak occurs; (b) that increases in the upper conduction-band-valley effective masses dramatically decrease the saturation
drift velocity, with very little other effect; (c) that increased nonparabolicity of the lowest conduction-band valley leads
to a broadening and shifting to higher electric fields of the peak in the velocity-field characteristic; (d) that increases
in the intervalley energy separation lead to moderate increases in the peak drift velocity; and (e) that increases in the
degeneracy of the upper conduction-band valleys leads to a moderate decrease in the saturation drift velocity. 相似文献
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We report on the drift-diffusion based simulation of a wurtzite (WZ) GaN MESFET. The main emphasis is put on the influence of electron mobility modeling on DC current-voltage (I-V) characteristics of the WZ-GaN MESFET. Two different analytical expressions are used for the electron mobility as a function of electric field. The first model is based on a simple saturation of the steady-state drift velocity with electric field (conventional three-parameter model). The other model is more realistic since it well reproduces the drift velocity-field characteristics obtained by Monte Carlo (MC) calculations, revealing the peak drift velocity with subsequent saturation at higher electric fields. Thus, it should be implemented in the drift-diffusion model for a following device simulation. However, the MC electron transport data for WZ-GaN are influenced by the specific choice of the material and band structure parameters, resulting in a variation of drift velocity-field characteristics. In addition, it should be noted that the MC simulation also neglects crystal defects in GaN, which, for example, might lead to uncontrolled electron compensation and additional electron scattering. In the present study we show that the DC I-V characteristics of the WZ-GaN MESFET are strongly affected by the MC-like electron mobility model, in particular by the peak steady-state velocity and the shape of the velocity-field characteristics even for the same drift velocity saturation level 相似文献
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《Electron Device Letters, IEEE》1984,5(12):508-510
A two-dimensional numerical model is employed to simulate the device performance of the high electron mobility transistor. A 1- µm gate device is analyzed using the equilibrium velocity-field characteristic of GaAs. The calculation reveals existence of electron accumulation in the GaAs layer under the drain side end of the gate electrode. A quasi-piecewise linear velocity-field characteristic is also employed to simulate the velocity overshoot effect. The cutoff frequency is found to be improved by about 50 percent owing to the velocity overshoot effect. 相似文献
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《Electron Device Letters, IEEE》2008,29(11):1190-1192
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《Electron Devices, IEEE Transactions on》1987,34(5):953-956
The transient and steady-state velocity-field characteristics of InP at 300 K are calculated for short samples by using a Monte Carlo model. It is found that the threshold field for negative differential resistance increases with a decrease in the sample length, but the peak-valley velocity ratio is almost independent of the sample length. 相似文献
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Experimental and theoretical studies have been made of electron transport and hot electron effects in PbTe and Pb1?xSnxTe as a function of alloy composition. Pulsed measurements of the current-voltage characteristics, Hall effect, and the potential distribution were made on epitaxial samples. Current instabilities and high field domain formation were observed. Monte-Carlo calculations of the velocity-field characteristic including the scattering into conduction band W valleys were performed. Reasonable agreement was obtained for the threshold field dependence on alloy composition. 相似文献
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《Electron Devices, IEEE Transactions on》1985,32(6):1092-1102
We develop a model for the high electron mobility transistor (HEMT) in which we include both hot-electron effects and conduction outside the quantum subband system using hydrodynamic-like transport equations. With such a model we can assess the significance of the various physical phenomena involved in the operation of the HEMT. We calculate results with a two-dimensional numerical technique for both steady-state and transient operation. For a 3-µm device at 77 K, we determine a transconductance of 450 mS/mm, a current-switching speed of 6 ps, and a capacitive charging speed of 4 ps/fanout gate which corresponds to the performance measured by other workers. We also see that electronic heating, velocity overshoot, and conduction outside the quantum well are significant near the pinchoff point. We conclude that the advantage of HEMT is twofold. The excellent conduction in the quantum well results in a low access resistance, and the low impurity concentration in the GaAs results in optimum overshoot effects. 相似文献
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Ⅲ族氮化物及其二维电子气输运特性的研究进展 总被引:1,自引:0,他引:1
薛舫时 《固体电子学研究与进展》2004,24(3):265-274,280
Ⅲ族氮化物半导体具有宽禁带和直接带隙 ,导带能谷间距大 ,强场输运特性好。Al Ga N/Ga N异质结产生高密度的二维电子气 ,屏蔽了杂质和缺陷的散射 ,改善了低场输运性能。它弥补了宽禁带半导体输运性能差的缺点 ,已研制成大功率的 HFET。利用强场下的速度过冲有望消除阴极端的速度凹坑 ,显著改进器件性能。电子气的强二维性使输运特征依赖于器件结构和工作状态 ,器件设计变为一个剪裁电子状态和输运特性的复杂工程。文中综述了 族氮化物及其二维电子气的输运特性 ,讨论了从输运特性出发 ,优化 HFET性能的问题。 相似文献
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The doping dependence of the velocity-field characteristic in InGaAs has been investigated by an analysis of measurements
with transferred-electron devices. The electron peak velocity has been determined directly as a function of electron concentration
and low-field mobility. The carrier-concentration dependence of the velocity-field characteristic has been deduced by comparing
experimental and theoretical transient device behaviour. The experimental results support a theoretical approach for the velocity-field
characteristic which has been proposed recently. 相似文献