HBT空间电荷区复合电流的解析模型

建立了异质结双极晶体管ＥＢ结空间电荷区复合电流的解析模型,基于该模型计算出了不同基区掺杂浓度下空间电荷区的复合率,获得了空间电荷区复合电流随机加电压的变化关系。     

Si开关晶体管电荷存贮效应的模拟

对硅开关晶体管来说,在基极驱动电流I_B_1和反抽电流I_B_2固定的条件下,测量出的存贮时间t_s随集电极电流的增加而增加或不变.这种现象是无法用一般常用的Ebers-Moll模型来解释和模拟的.通过实验我们看到:在这种开关晶体管中集电结正向电流主要是空间电荷区中的复合电流而不是注入电流.而空间电荷区中的复合电流并不伴随着电荷存贮,因而可以起抗饱和的作用.而抗饱和的程度受到集电极串联电阻,集电极电流,基极串联电阻和电流增益的影响.我们称这种效应为空间电荷区复合流抗饱和效应.我们提出考虑此效应的模型.用此模型可以模拟一般Ebers-Moll模型无法模拟的硅开关晶体管的特性,使计算结果和实验符合得较好.     

高温Al0.3Gao.22In0.48P/GaAs HBT电流增益的计算分析

建立了Al0.3Ga0 22In0.48P/GaAs异质结双极型晶极管(HBT)中电流输运过程的模型,利用实验得到的材料特性参数进行了HBT电流增益随温度变化的模拟。随着温度上升,小电流时电流增益下降较多,而大电流时电流增益基本保持不变.模拟表明,小电流下电流增益的下降主要是由eb结空间电荷区的复合电流随温度增加而造成的;而大电流下电流增益直至723K下降仍小于10％.最高工作温度可达848K.由于采用的计算方法充分考虑了空间电荷区复合电流的影响,模拟结果较为符合实际情况,可为研制高性能HBT器件所需材料提供参考依据。     

高温Al_(0.3)Ga_(0.22)In_(0.48)P/GaAsHBT电流增益的计算分析

建立了Ａｌ０．３Ｇａ０．２２Ｉｎ０．４８Ｐ／ＧａＡｓ异质结双极型晶极管（ＨＢＴ）中电流输运过程的模型,利用实验得到的材料特性参数进行了ＨＢＴ电流增益随温度变化的模拟．随着温度上升,小电流时电流增益下降较多,而大电流时电流增益基本保持不变．模拟表明,小电流下电流增益的下降主要是由ｅｂ结空间电荷区的复合电流随温度增加而造成的;而大电流下电流增益直至７２３Ｋ下降仍小于１０％．最高工作温度可达８４８Ｋ．由于采用的计算方法充分考虑了空间电荷区复合电流的影响,模拟结果较为符合实际情况,可为研制高性能ＨＢＴ器件所需材料     

AlGaAs／GaAs缓变异质结双极晶体管空间电行区中的复合电流

本文建立了包括空间电荷区复合电流在内的缓变异质结双极晶体管（ＨＢＴ）的分析模型．对ＡｌＧａＡｓ／ＧａＡｓＨＢＴ特性的分析表明，缓变发射结虽可有效地消除导带边的势垒尖峰，但也会大大增加空间电荷区中的复合，导致小电流情况下电流增益的明显下降．发射结界面附近的不掺杂隔离层会进一步增大空间电荷区内的复合，加剧电流增益的下降．因此在器件的设计和制作过程中，应精确控制组分缓变区和不掺杂隔离层的厚度，以减小空间电荷区中的复合电流，获得较好的器件特性．     

AlGaAs／GaAs缓变异质结双极晶体管空间电荷区中的复合电流

本建立了包括空间电荷区复合电流在内的缓变异质结双极晶体管（ＨＢＴ）的分析模型，对ＡｌＧａＡｓ／ＧａＡｓＨＢＴ特性的分析表明，缓变发射结中可有效地消除导带边的势垒尖峰，但也会大大增加空间电荷区中的复合，导致小电流情况下电流增益的明显下降，发射结界面附近的不掺杂隔离层会进一步增大空间电荷区内的复合，加剧电流增益的下降，因此在器件的设计和制作过程中，应精确控制组分缓变区和不掺杂隔离层的厚度，以减小空间     

CdTe/CdS多晶薄膜太阳能电池正向电流的计算机模拟分析

应用数值方法来解CdTe／CdS异质结J－V特性，进而得出其二极管理想因子、激活能以及异质结空间电荷区党度。结果表明，CdTe一侧空间电荷区复合是主导CdTe／CdS异质结传输电流的主要机制。说明在CdTe基太阳能电池制造中，控制多晶薄膜化学缺陷对提高电池能量转换效率的重要意义。     

GaAlAs红外发光二极管1/f噪声研究

在宽范围偏置条件下,测量了GaAlAs红外发光二极管（IRLED）的低频噪声,发现1／f噪声幅值与偏置电流If^γ的r次方成正比,在小电流区,r≈1。在大电流区r≈2。建立了一个GaAlAs IRLED的1／f噪声模型,得到与实验一致的定性结果。基于该模型的分析表明．低电流区GaAlAs IRLED的1／f噪声源于体陷阱对非平衡载流子俘获和发射导致的扩散电流涨落,高电流区的1／f噪声源于结空间电荷区附近氧化层陷阱对该处表面势的调制而引起载流子表面复合速率的涨落。该研究结果为1／厂噪声表征GaAlAs IRLED的可靠性提供了实验基础与理论依据。     

突变异质结双极晶体管中的复合效应与电流传输

建立了带有不掺杂隔离层的突变异质结双极晶体管（ＨＢＴ）模型，在热场发射－扩散（ＴＦＤ）理论的基础上，又考虑了空间电荷区中的复合效应。对ＡｌＧａＡｓ／ＧａＡｓＨＢＴ特性的分析表明，不掺杂隔离层虽可有效地降低导带边的势垒尖峰，提高发射结的注入效率，但也会增大空间电荷区中的复合电流。因此，在实际器件的设计和制作中，应适当选择不掺杂隔离层的厚度，以获得较好的器件特性。还给出了计算突变异质结界面处电子准费米能级不连续的公式。     

光照对锑化铟p-n结的噪声和其它一些特性的影响

研究了在T=77°K时的锑化铟p-n结在各种偏压和照度下的低频(频率=20赫-20千赫)噪声频谱。发现在无光照时,欧姆漏电流起伏是电流噪声的主要原因。只是在足够大的正偏压时,才发现空间电荷区有电导起伏。光照期间光电流的起伏对过剩噪声有很大的影响。表明在空间电荷区内产生了电流起伏,其起伏程度不仅取决于电压的偏压值,而且也取决于照度级L。还发现P-n结的其他一些特性也都以照度级为条件:二极管的光电效率随照度级L的增大而降低,并且在恒偏压下测定的p-n结正电流以及空间电荷区的等效微分电导都有增大。这种变化可解释为空间电荷区内的载流子寿命缩短了,或空间电荷区的宽度增大了。引证了一些宗数,来证明这个论点:即仅在以电流电导的特殊机理为表征的空间电荷区的某些区内,产生电导的过度起伏。     

Distribution of recombination currents in the space charge regionof heterostructure bipolar devices

This paper addresses the problem of the space charge region Shockley-Read-Hall (SRH) recombination currents in heterojunctions with one noncrystalline side. A formulation which generalizes previous works is discussed. The approach is based on the drift-diffusion model with a thermionic-field emission boundary condition. The main physical parameters which determine the relative contribution of each zone of the space charge region (SCR) to the total recombination current are identified. The general analysis is applied for the first time to amorphous/crystalline heterojunctions and design criteria are established to minimize the total recombination current     

The effect of grain boundary shunt currents on mis solar cell performance

The degradation of solar cells by grain boundaries can take any of three forms: recombination of minority carriers, forward current due to recombination in the space charge region of the junction or Schottky barrier, or forward currents due to shunting. There is no doubt that minority carrier recombination occurs and degrades the short circuit current. There seems little doubt that grain boundaries also degrade the solar cell open circuit voltage, but whether the degradation is due to recombination in the space charge region or due to shunting is not clear. To date most attention has been paid to space charge recombination. There is data, however, that shunt currents can flow, especially in doped regions of the grain boundaries with the conductivity along the grain boundary estimated from that data to be 10⁻¹² to 10⁻⁵ mhos/square. We will present an analysis assuming such grain boundary conductivities and show that the predictions of such a shunt model are in agreement with experiment. Specifically the shunt current is predicted to increase exponentially as qV/2kT where V is the forward bias, the shunt current significantly lowers the open circuit voltage, and it has negligible effect on the short circuit current.     

Improved analysis of pulsed C-t measurements on silicon MOS capacitors

A modified analysis of the pulse response of silicon MOS capacitors is presented which takes into account the lateral spreading of the depletion region around the gate area. Two aspects of this lateral depletion region which have previously been ignored, namely the bulk generation and space charge in this region, are taken into account and used to explain the experimentally observed dependence of the capacitor relaxation time on the device aspect ratio. The analysis allows the bulk lifetime to be obtained more accurately and also enables the surface recombination velocity resulting from a particular device processing schedule to be estimated. The results obtained agree well with those determined from junction leakage current measurements and the relevance of the lateral edge effect to the characteristics of a more complex charge coupled device has been discussed.     

Impact of fluorine incorporation in the polysilicon emitter of NPNbipolar transistors

We demonstrate that fluorine incorporation in the polysilicon emitter of NPN bipolar transistors significantly reduces the current gain h_fe. The gain degradation can be related to a reduction of the barrier to hole transport at the poly-Si/mono-Si interface. In addition to a gain reduction, fluorinated-emitter transistors display lower base recombination currents (at low base-emitter biases) than nonfluorinated emitter devices, suggesting that fluorine passivates recombination centers in the emitter-base space charge region     

Experimental comparison of base recombination currents in abrupt and graded AlGaAs/GaAs heterojunction bipolar transistors

The relative importance of the base bulk recombination current and the base-emitter junction space charge recombination current is examined for AlGaAs/GaAs HBTs with different grading schemes in the base-emitter junction. Experimental results demonstrate that, in abrupt HBTs, the base bulk recombination current is larger, and the base current increases with the base-emitter bias with an ideality factor of approximately 1. In contrast, in graded HBTs, the space charge recombination current dominates and the base current ideality factor is approximately 2. These experimental results agree well with a published theoretical calculation.<>     

低温高注入硅双极晶体管电流增益的定量模拟

本文考虑了基区复合电流，发射结空间电荷区复合电流，基区高注入引起的禁带变窄效应，Ｅａｒｌｙ效应，基区和发射区电导调制效应，有效基区展宽效应以及发射区电流集边效应，定量地模拟了硅双极晶体管电流增益在７７Ｋ和３００Ｋ时与集电极电流的关系，并且与实验结果相吻合，计算还表明在低温７７Ｋ时，电流增益的大注入效应由基区电导调制效应和发射区电流集边效应决定，而在３００Ｋ时则由有效基区展宽效应决定。     

Large signal turn-on response of the junction transistors including nonlinear effects

The large-signal transient behavior of transistors must be considered as nonlinear phenomena. In this paper, the nonlinearity of the transient behavior of transistors in the active region are considered, and the charge control method is extended to include this nonlinearity. Using a one-dimensional homogeneous-base transistor model, the current variation of small-signal time constants in the charge control concept are analyzed in terms of emitter efficiency, surface recombination, and generated field in the base region. From the results of the small signal analysis, the large-signal time constants have been defined as a function of injection ratio. From the charge control equation founded on the large-signal time constants, the rise time is calculated including the current variations of time constants and voltage variation of junction capacitance. The results of the analysis are also verified by experimental measurements.     

Potential probing of a thyristor cross-cut during turn-on

On a cross-cut of a thyristor with a particularly wide n-base, the dynamic change in voltage at the surface was probed during turn-on. Furthermore, the infrared recombination radiation emitted from the regions of carrier storage was observed time-resolved. The results show that during the turn-on delay phase, the load current flows in a channel that widens significantly from the n-emitter towards the p-emitter. Compensation of the stationary charge in the space charge region by free electrons results in a movement of the space charge region towards the p-emitter. Concurrently, the particular distribution of electrons causes the region of maximum fieldstrength to move away from the junction.