Analytical Modeling and Simulation of Heterojunction Emitter Bipolar Transistors

• Main Authors: Bor-Yau Yang, 楊博堯
• Other Authors: S. J. Wang
• Format: Others
• Language: en_US
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/18081213277357174572

碩士 === 國立成功大學 === 電機工程研究所 === 81 === In this thesis, an analytical model for the heterojunction emitter bipolar transistors (HEBTs) is developed. The HEBT, which has a homojunction emitter with a heterojunction confinement layer on top of it, combines the merits of homojunction and regular heterojucntion bipolar transistors and is simple for fabrication. In the present model, the model parameters are directly related to device parameters such as doping densities, dimensions, and band offset, etc. The effects of carrier recombination at the heterointerface of the narrow- and wide-bandgap emitters, in the quasi-neutral emitter and base regions, in the e-b SCR, and at the surface of the e-b SCR edge have been considered. Physical insight of the influence of the thickness, the valence band discontinuity, and the junction velocity of the narrow-bandgap emitter layer on device performance is investigated. Based on an AlGaAs/GaAs HEBT, the calculated results obtained from this analytical model are compared with experimental data. It is found that the common- emitter I-V characteristics from the present model are in good agreement with the experimental data. In addition, the modeling of current-dependent cutoff frequency has been also investigated. The proposed analytical equations discribe very well for high-current base-widening, current-dependent b-c junction capacitance, etc. Optimization of HEBT design is discussed based on current-dependent analysis. This model can be used for homojunction BJTs, both single and double heterojunction bipolar transistors, and heterojunction emitter bipolar transistors.