论文标题:Ⅲ-Ⅴ族化合物半导体输运性质的蒙特卡罗模拟
Monte Carlo Simulation of Electron Transport Properties in Ⅲ-Ⅴ Compound Semiconductors
论文作者
论文导师 吕燕伍,论文学位 硕士,论文专业 凝聚态物理
论文单位 北京交通大学,点击次数 119,论文页数 77页File Size4550K
2007-12-01论文网 http://www.lw23.com/lunwen_342686182/
Monte Carlo simulation;; III-V compound semiconductor;; transport properties;; GaAs MESFET;; Indium Phosphide
以GaAs，InP为主Ⅲ-V族化合物半导体材料具有很宽的带隙，大都为直接跃迁型能带，光电转换效率较高，以及具有很高的饱和电子漂移速度和迁移率。因此Ⅲ-V族化合物半导体在微电子学和光电子学方面得到日益重要和广泛的应用，对其输运性质的研究是非常有价值的，对材料的应用更是具有基础性的意义。 蒙特卡罗模拟方法是应用于半导体器件模拟，进行载流子的输运研究的常用而可靠的工具。基于大量物理事件的蒙特卡罗模拟统计方法是一种采用概率解决物理问题的统计数值方法，它基于半经典输运模型直接求解玻耳兹曼方程，是模拟存在非本地输运的半导体材料和小尺寸器件特性的有效方法。应用于半导体中载流子输运的蒙特卡罗方法，是在给定的散射机制和外加电场的作用下，模拟载流子在半导体晶体里的运动。载流子的运动由碰撞和外电场共同决定，碰撞以随机的方式影响在外电场的作用下的载流子的运动。碰撞的影响可用散射率来估算，电场对载流子的作用可用经典运动法则来计算。 本文给出了系统的蒙特卡罗模拟的理论模型和模型的优化，包括载流子主要的散射机制、器件电场电荷计算和主要物理量的统计计算。根据对以GaAs、GaP和InP为主的Ⅲ-V族化合物半导体材料的能带结构和散射机制的分析，采用蒙特卡罗模拟方法，研究了亚微米尺寸的OaAs MESFET器件的电子密度分布、电场强度、漂移速度和迁移率分布等输运性质，以及栅长对器件性质的影响和电流电压特性。随着栅长尺寸的增加，栅下沟道的电子漂移速度减小，而且漏电流呈线性递减。同时计算了GaP和InP体材料输运性质，分析了它们的电场强度、漂移速度和迁移率在不同偏置电压下的空间分布，以及电子密度和漂移速度在高电场下的过冲现象。本文的计算结果更深入地解释了Ⅲ-V族化合物半导体的输运现象，并且有助于半导体器件应用和设计。
The GaAs, InP-based III-V compound semiconductors, which are known as their wide band-gaps, direct-band transition, high photoelectric conversion efficiency and high saturated electron drift velocity and mobility, become increasingly important and have been widely used in microelectronics and optoelectronics. It is quite valuable to study their transport properties which are the foundation of the applications using these materials. Monte Carlo simulation method is a popular and reliable tool which has been applied to study the carrier transport properties of semiconductor device for many years. It is a statistical probability method which solves physics problems using statistical numerical theory and solves Boltzmann equation directly based on semi-classical transport mode. It"s a effective way to simulate the non-local transport properties of semiconductor materials and small size devices. The Monte Carlo method applied to semiconductor carrier transport simulates the movement of the carriers in the semiconductor crystal under the scattering and the external electric field. The carrier"s movement depends on the collision and external electric field. The impact of the collision can be estimated by the scattering rate, and the process of carrier under the electric field can be calculated using classical mechanics. This paper presents a systematic theoretical Monte Carlo simulation model and its optimization, including the main scattering mechanisms of carriers, the calculation of electric field and electron charge in devices and the statistical calculation of the primary physical quantities. The transport and current-voltage properties of submicron GaAs MESFET device are calculated firstly based on the nonparabolic effective mass energy band model and Monte Carlo method which includes all major scattering mechanisms. The electron drift velocity, electric field and the non-homogeneity of mobility distribution in device are obtained. The influences of different gate lengths to electron drift velocity and drain current are analyzed. It is shown that the electron drift velocity decreases rapidly and the drain current decreases linearly when increasing gate length. Secondly, the spatial distribution of transport properties of GaP and InP bulks, including electric fields, drift velocities and mobility, are calculated at different applied voltages and an overshoot phenomena in the electron densities and drift velocities of the GaP and InP bulks under the high electric field was found. The results obtained by this paper make further explanations of III-V compound semiconductor transport phenomena, and are helpful for designing semiconductor devices.
|
