超导－半导场效应晶体管理论分析

分析了超导－半导场效应晶体管的工作原理，利用电阻分流模型对其性能进行了讨论，并给出了详细的计算结果。其中认为沟道中载流子分布符合费米－狄拉克分布函数，并考虑了沟道载流子迁移率的变化。     

杂质浓度对槽栅PMOSFET抗热载流子特性的影响

基于流体动力学能量输运模型 ,利用二维仿真软件 Medici研究了深亚微米槽栅 PMOS器件衬底和沟道掺杂浓度对器件抗热载流子特性的影响 ,并从器件内部物理机理上对研究结果进行了解释。研究发现 ,随着沟道杂质浓度的提高 ,器件的抗热载流子能力增强 ;而随着衬底掺杂浓度的提高 ,器件的抗热载流子性能降低。这主要是因为这些结构参数影响了电场在槽栅 MOS器件内的分布和拐角效应 ,从而影响了载流子的运动并使器件的热载流子效应发生变化     

不同沟道长度MOSFET的热载流子效应

对同一工艺制作的几种不同沟道长度的 MOSFET进行了沟道热载流子注入实验。研究了短沟 MOS器件的热载流子效应与沟道长度之间的关系。实验结果表明 ,沟道热载流子注入使 MOSFET的器件特性发生退变 ,退变的程度与器件的沟道长度之间有非常密切的关系。沟道长度越短器件的热载流子效应越明显 ,沟道长度较长的器件的热载流子效应很小。利用热载流子效应产生的机理分析和解释了这一现象     

直接栅MOSFET静电场传感器温度漂移模型和模拟

推导出了直接栅MOSFET静电场传感器的温度漂移系数,并研究了温度漂移的主要原因。此研究工作对消除直接栅MOSFET静电场传感器的温度漂移有一定的帮助。首先,建立了直接栅MOSFET静电场传感器沟道中电荷随温度变化的模型。其次,根据直接栅MOSFET沟道载流子浓度和载流子迁移率都为温度的函数,将直接栅MOSFET静电场传感器的温度漂移定义为由沟道载流子迁移率随温度变化引起的温度漂移系数αμ和由沟道载流子浓度随温度变化引起的温度漂移系数αQ,并对它们与温度的关系作了推导和研究。最后,对沟道载流子迁移率随温度变化引起的温度漂移系数αμ和由沟道载流子浓度随温度变化引起的温度漂移系数αQ进行了模拟和比较。模拟结果表明,温度漂移系数αμ远小于温度漂移系数αQ。因此沟道载流子浓度随温度变化是直接栅MOSFET静电场传感器的温度漂移的主要原因。     

红外区熔再结晶SOI GE_XSi_(1-X)合金沟道P-MOSFET的研究

在红外区熔再结晶SOI材料上用MBE的方法形成Si／GexSi1－x／Si量子阱结构．在此基础上，采用常规的P－MOS工艺制造出了SOIGexSi1-x合金沟道P－MOSFET．为避免GexSi1-x合金材料发生蜕化，MBE以后除快速热退火（RTA）以外的所有工艺温度都不超过800℃．直流特性的测量结果表明，与普通Si沟道器件相比，GexSi1-x合金沟道器件的沟道载流子迁移率有所提高．而且，这种器件在性能的进一步提高方面存在着相当大的潜力．     

深亚微米薄层SOI/MOSFET’s热载流子效应分析

本文从二维模拟热载流子注入电流入手，讨论了不同硅层厚度、栅氧厚度和掺杂浓度对薄层深亚微米ＳＯＩ／ＭＯＳＦＥＴ’ｓ热载流子效应的影响．模拟结果表明，对于不同的硅层厚度，沟道前表面漏结处的载流子浓度对热载流子效应起着不同的作用，有时甚至是决定性的作用．沟道前表面漏结处的载流子浓度和沟道最大电场一样，是影响薄层ＳＯＩ／ＭＯＳＦＥＴ’ｓ热载流子效应的重要因素，这也就解释了以往文献中，随着硅层减薄，沟道电场增大，热载流子效应反而减小的矛盾．模拟也显示了在一定的硅层厚度变化范围内（６０～１００ｎｍ），器件热载流子效应     

高可靠性P-LDMOS研究

分析了沟道高电场分布产生原因及各个参数对高电场的影响,提出了两条沟道设计的原则——拉长沟道同时降低沟道浓度.模拟结果显示,两条原则能够有效地降低沟道两端的两个峰值电场,从而缓解沟道热载流子效应,提高P-LDMOS的可靠性.     

高可靠性P-LDMOS研究

分析了沟道高电场分布产生原因及各个参数对高电场的影响,提出了两条沟道设计的原则--拉长沟道同时降低沟道浓度.模拟结果显示,两条原则能够有效地降低沟道两端的两个峰值电场,从而缓解沟道热载流子效应,提高P-LDMOS的可靠性.     

深亚微米槽栅PMOS结构对抗热载流子效应的影响

基于流体动力学能量输运模型 ,利用二维仿真软件 MEDICI对深亚微米槽栅 PMOS器件的结构参数 ,如凹槽拐角、负结深、沟道和衬底掺杂浓度对器件抗热载流子特性的影响进行了研究 ,并从器件物理机制上对研究结果进行了解释。研究发现 ,随着凹槽拐角、负结深的增大和沟道杂质浓度的提高 ,器件的抗热载流子能力增强。而随着衬底掺杂浓度的提高 ,器件的抗热载流子性能降低。结构参数影响了电场在槽栅 MOS器件的分布和拐角效应 ,从而影响了载流子的运动并使器件的热载流子效应发生变化。     

基于能带计算的纳米尺度MOS器件模拟

随着器件沟道长度的不断缩小，多栅结构（包括FinFET）被普遍认为是有效改进Ion/Ioff的手段. 量子力学效应对MOSFET中载流子分布和输运的影响已被认识和研究多年. 在沟道截面被局限在数纳米量级时，一个更基本的固体物理问题，即能带或电子结构对材料几何尺寸的依赖性，逐渐显现出来并对器件特性产生不可忽略的影响. 本文讨论如何从第一原理出发，高效率地计算沟道区的能带结构. 在得到载流子的输运参数（有效质量、迁移率等）的基础上，通过直接求解带开放边界条件的薛定谔方程以得到器件的电学特性. 考虑到应力对能带结构和散射机制的影响，还研究了载流子迁移率与晶向的关系.     

低温载流子冻析效应及其对半导体器件电性能的影响

结合载流子热激发和场致激发的电离理论，对计算电离杂质浓度的物理模型和计算方法进行了修正，由于考虑了载流子的费米统计分布、载流子对杂质电离能的屏蔽作用、ＰｏｏｌｅＦｒｅｎｋｅｌ强场理论和自加热等物理效应的影响，因而可精确描述低温下载流子冻析效应、浅能级杂质的陷阱行为及其对低温器件交直流性能的影响。     

Theoretical analysis of the quantum photoelectric yield in Schottky diodes

A detailed analytical calculation of the photoelectric quantum yield in Schottky diodes is presented. The transport of carriers in the surface space charge region is treated explicitly, taking account of photogeneration, diffusion and drift in the non-uniform electric field. Boundary conditions at the interface are expressed in terms of surface recombination velocity and emission velocity of excess carriers into the metal.It is shown that the metal-semiconductor interface strongly affects the collection efficiency of short wavelength generated electron-hole pairs. This effect basically originates in the emission flux of majority carriers into the metal.Current, charge carriers distributions and quantum yields are computed using the data of AuCdTe Schottky barriers.     

InGaAs（P）应变多量子阱激光器的理论分析与优化设计

本文从理论上分析计算并给出了ＩｎＧａＡｓ（Ｐ）应变多量子阱激光器的优化设计参数，考虑到多量子阱阱区的注入不均匀性，提出了一种新的分析和设计方法。对于激射波长为１．５５微米的１．５％压缩应变多量子阱激光器，最佳的阱数为四个，最佳腔长为５００微为左右．     

Phase noise of mixers

A formula is derived for the output phase noise of a mixer when both the radio frequency RF and local oscillator LO carriers are impaired by phase noise. The calculation uses test results obtained with three discrete carriers. An application of the noise formula to frequency synthesis is included.     

High-frequency conductivity of a thin cylindrical semiconductor wire at arbitrary temperatures

The high-frequency conductivity of a thin straight semiconductor wire with a circular cross section is treated in the context of the classical kinetic theory. The calculation is conducted for an extrinsic semiconductor with a simple band structure at any degree of degeneracy. The relation between the wire radius and the mean free path of charge carriers is taken to be arbitrary. The diffuse mechanism of reflection of charge carriers from the wire boundary is considered.     

Phonon-assisted carrier transport across a grain boundary

A general theory of phonon-assisted transition of majority carriers across a grain boundary (GB) is formulated with the GB angle as a variable. It is found that the bulk relaxation time in the crystalline region and the transition time at the GB are the important parameters that determine the transmission coefficient of carriers across the GB. Using the proposed model, an n-type polycrystalline silicon is employed as an example in a numerical calculation.     

Impact-ionization and noise characteristics of thin III-V avalanchephotodiodes

It is, by now, well known that McIntyre's localized carrier-multiplication theory cannot explain the suppression of excess noise factor observed in avalanche photodiodes (APDs) that make use of thin multiplication regions. We demonstrate that a carrier multiplication model that incorporates the effects of dead space, as developed earlier by Hayat et al. provides excellent agreement with the impact-ionization and noise characteristics of thin InP, In_0.52 Al_0.48As, GaAs, and Al_0.2Ga_0.8As APDs, with multiplication regions of different widths. We outline a general technique that facilitates the calculation of ionization coefficients for carriers that have traveled a distance exceeding the dead space (enabled carriers), directly from experimental excess-noise-factor data. These coefficients depend on the electric field in exponential fashion and are independent of multiplication width, as expected on physical grounds. The procedure for obtaining the ionization coefficients is used in conjunction with the dead-space-multiplication theory (DSMT) to predict excess noise factor versus mean-gain curves that are in excellent accord with experimental data for thin III-V APDs, for all multiplication-region widths     

High-frequency admittance of n-v-n space-charge-limited current (SCLC) solid-state devices

A calculation has been made of the HF admittance of n-v-n SCLC devices by a simple method that takes into account the thermally generated free carriers in the central bulk region. The assumption made is that the thermal carrier density is relatively small such that the principal dc properties of the SCLC device still prevail. The calculated results indicate that the effect of the thermal free carriers is to reduce the oscillatory nature of the device HF admittance components.     

A field-funneling effect on the collection of alpha-particle-generated carriers in silicon devices

We studied the transient characteristics of charge collection from alpha-particle tracks in silicon devices. We have run computer calculations using the finite element method, in parallel with experimental work. When an alpha particle penetrates a pn-junction, the generated carriers drastically distort the junction field. After the alpha particle penetration, the field, which was originally limited to the depletion region, extends far down into the bulk silicon along the length of the alpha-particle track and funnels a large number of carriers into the struck junction. After a few nanoseconds, the field recovers to its position in the normal depletion layer, and, if the track is long enough, a residue of carriers is left to be transported by diffusion. The extent of this field funneling is a function of substrate concentration, bias voltage, and the alpha-particle energy.