共查询到17条相似文献,搜索用时 140 毫秒
1.
禁带变窄效应对突变AlGaAs/GaAs HBT电流影响的研究 总被引:2,自引:2,他引:0
重掺杂使导带、价带带边同时发生了收缩,从而产生禁带变窄效应(BGN)。对于基区重掺杂Npn突变AlGaAs/GaAsHBT,BGN引起导带和价带突变界面势垒形状及高度都发生了改变,这对基区、集电区电流产生重要的影响。文中基于Jain-Roulston禁带收缩模型及热场发射-扩散载流子输运机制,对这一现象进行了深入的研究。通过与其它计算程序常用的几种BGN模型比较得出为了更好描述电流传输,利用Jain-Roulston的BGN模型,考虑禁带变窄量在导带、价带有不同的分配,从而对电流有不同的影响是必要的。 相似文献
2.
3.
4.
5.
超高掺杂GaAs具有明显的禁带变窄(BGN)效应,因此采用超高掺杂基区的GaAs同质晶体管也可获得HBT的效果.故称之为赝HBT(p—HBT)。本文根据实验结果讨论了超高掺杂情况下GaAs的BGN效应及其对有效本征载流子浓度的影响,并对np~+n型结构GaAs p—HBT的发射极注入效率和共发射极电流增益进行了理论分析。结果表明,当基区掺杂浓度高于1×10~(20)/cm~3时可以获得较好的器件特性。 相似文献
6.
7.
具有AlGaAs缓变结构的InGaP/GaAs HBT性能改进分析 总被引:1,自引:0,他引:1
对改进型结构具有零导带势垒尖峰的缓变InGaP/AlGaAs/GaAs HBT器件的直流和高频特性进行了理论探讨,并同传统突变结构的InGaP/GaAs HBT的相应性能作了比较。结果表明:在低于30 nm的一定范围内的缓变层厚度下,与突变的InGaP/GaAs HBT相比,改进型结构的InGaP/AlGaAs/GaAs HBT具有更低的offset和开启电压、更强的电流驱动能力、更好的伏-安输出特性和高频特性。 相似文献
8.
9.
10.
11.
Heavy doping of the base in HBTs brings about a bandgap narrowing (BGN) effect, which modifies the intrinsic carrier density and disturbs the band offset, and thus leads to the change of the currents. Based on a thermionic-field-diffusion model that is used to the analyze the performance of an abrupt HBT with a heavydoped base, the conclusion is made that, although the BGN effect makes the currents obviously change due to the modification of the intrinsic carrier density, the band offsets disturbed by the BGN effect should also be taken into account in the analysis of the electrical characteristics of abrupt HBTs. In addition, the BGN effect changes the bias voltage for the onset of Kirk effects. 相似文献
12.
Heavy doping of the base in HBTs brings about a bandgap narrowing(BGN)effect,which modifies the intrinsic carrier density and disturbs the band offset,and thus leads to the change of the currents.Based on a thermionic-field-diffusion model that is used to the analyze the performance of all abrupt HBT with a heavydoped base,the conclusion is made that,although the BGN effect makes the currents obviously change due to the modification of the intrinsic carrier density,the band offsets disturbed by the BGN effect should also be taken into account in the analysis of the electrical characteristics of abrupt HBTs.In addition,the BGN effect changes the bias voltage for the onset of Kirk effects. 相似文献
13.
Abrupt heterojunction bipolar transistors (HBTs) show interfaces where discontinuities in the energy levels appear. Currents through these interfaces are controlled by tunneling and thermionic emission. The values of these currents depend on the form and height of the energy barriers, which are disturbed by the heavy doping effects on semiconductor energy band structure. In this work, the real bandgap narrowing is distributed between the conduction and valence bands according to Jain-Roulston model, and its effect on the base and collector currents of Si/SiGe and InP/InGaAs HBTs is analyzed. This analysis is carried out through a numerical model which combines the drift-diffusion transport in the bulk of transistor with the thermionic emission and tunneling at the base-emitter interface, and an empirically determined surface recombination current 相似文献
14.
This work examines the impact of bandgap offset distribution between conduction and valence bands in Si-based graded bandgap HBT's using dc and ac simulation. For a fixed total bandgap offset, a conduction band pushed up by the total offset, together with a valence band pushed up by 2× the total offset gives the best ac performance, and allows the highest operational current for high frequency applications in an n–p–n HBT. A retrograded mole fraction profile, when properly optimized, can produce nearly identical ac performance for different bandgap offset distributions. These suggest that contrary to popular belief, applying careful optimization can yield excellent transistor performance for any arbitrary band alignment for both n–p–n and p–n–p graded bandgap HBT's. 相似文献
15.
A new tunnelling model is described which treats the interfacial layer in a polysilicon emitter transistor as a wide bandgap semiconductor. Potential barriers are formed in the valence and conduction bands, the sizes of which vary with the dopant type and concentration in the interfacial layer.<> 相似文献
16.
针对应变Si1-xGex的应变致能带分裂及重掺杂对裂值的影响,提出了多子双带结构的等价有效简并度模型和有关算法。模型中考虑了非抛物线能带结构。应用该模型,计算了赝形生长在(100)Si衬底上的Si1-xGex应变层的重掺杂禁带窄变,发现当掺杂超过一定浓度(对于p型和n型合金,该浓度分别约为1.9×1019cm-3和3.5×1019cm-3)后,它在某一Ge组分下得到极大值,而当掺杂低于这个浓度时,它则随Ge组分的增加单调下降。文中还将计算结果与其它未细致考虑应变致能带分裂因素的理论工作进行了比较。 相似文献
17.
Yang-Yu Fan Nieh R.E. Lee J.C. Lucovsky G. Brown G.A. Register L.F. Banerjee S.K. 《Electron Devices, IEEE Transactions on》2002,49(11):1969-1978
Based on the energy-dispersion relation in each region of the gate-dielectric-silicon system, a tunneling model is developed to understand the gate current as a function of voltage and temperature. The gate capacitance is self-consistently calculated from Schrodinger and Poisson equations subject to the Fermi-Dirac statistics, using the same band structure in the silicon as used for tunneling injection. Franz two-band dispersion is assumed in the dielectric bandgap. Using a Wentzel-Kramer-Brillouin (WKB)-based approach, direct and Fowler-Nordheim (FN) tunneling and thermionic emission are considered simultaneously. The model is implemented for both the silicon conduction and valence bands and both gate- and substrate-injected currents. ZrO/sub 2/ NMOSFETs were studied through temperature-dependent C/sub g/-V/sub g/ and I/sub g/-V, simulations. The extracted band gaps and band offsets of the ZrO/sub 2/- and interfacial-Zr-silicate-layer are found to be comparable with the reported values. The gate currents in ZrO/sub 2/-NMOSCAPs are found to be primarily contributed from the silicon conduction band and tunneling appears to be the most probable primary mechanism through the dielectric. Oscillations of gate currents and kinks of gate capacitance were observed near the flat-band in the experiments. These phenomena might be caused by the interface states. 相似文献