1264 IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 48, NO. 6, JUNE 2001 Simulation of Power Heterojunction Bipolar Transistors on Gallium Arsenide Vassil Palankovski, Ruediger Schultheis, and Siegfried Selberherr, Fellow, IEEE Abstract—We demonstrate the results of two-dimensional (2-D) hydrodynamic simulations of one-finger power heterojunction bipolar transistors (HBTs) on GaAs. An overview of the physical models used and comparisons with experimental data are given. We present models for the thermal conductivity and the specific heat applicable to all relevant diamond and zinc-blende structure semiconductors. They are expressed as functions of the lattice tem- perature and, in the case of semiconductor alloys, of the material composition. Index Terms—Electrothermal effects, heating, semiconductor device thermal factors, simulation software. I. INTRODUCTION H ETEROJUNCTION bipolar transistors (HBTs) attract much industrial interest because of their capability to operate at high current densities [1], [2]. AlGaAs/GaAs or InGaP/GaAs-based devices are promising candidates for power applications in modern mobile telecommunication systems. Heat generated at the heterojunctions cannot completely leave the device, especially in the case of III-V semiconductor materials. Therefore, significant self-heating occurs in the device and leads to a change of the electrical device character- istics. Accurate simulations save expensive technological efforts to obtain significant improvements of the device performance. The two-dimensional (2-D) device simulator MINIMOS-NT [3] is extended to deal with different complex materials and struc- tures, such as binary and ternary semiconductor III-V alloys with arbitrary material composition profiles. Various important physical effects, such as bandgap narrowing, surface recombi- nation, and self-heating, are taken into account. This paper describes the physical models and gives examples of simulations verified by measurements. II. THE PHYSICAL MODELS In previous work, we emphasized on bandgap narrowing as one of the crucial heavy-doping effects to be considered for bipolar devices [4]. We have developed a new physically-based analytical bandgap narrowing model, applicable to compound Manuscript October 23, 2000. The review of this paper was arranged by Ed- itor M. A. Shibib. V. Palankovski and S. Selberherr are with Institut für Mikroelektronik, Tech- nische Universität Wien, A-1040 Vienna, Austria. R. Schultheis is with Infineon Technologies AG, Wireless Systems WS TI S MWP, D-81730 Munich, Germany. Publisher Item Identifier S 0018-9383(01)04239-3. Fig. 1. Temperature dependence of the thermal conductivity. Comparison between experimental data and the model for Si, Ge, and GaP. Fig. 2. Temperature dependence of the thermal conductivity. Comparison between experimental data and the model for InP, GaAs, and InAs. Fig. 3. Material composition dependence of the thermal conductivity. Comparison between experimental data and the model for SiGe and InGaAs. 0018–9383/01$10.00 © 2001 IEEE