Study Of The Device Characteristics Of Antimonide-Based Inp Dhbts

The InP DHBTs device with antimony-contained base show great frequency characteristic, breakdown characteristic and thermal characteristic because of their special staggered II-type band alignment, and further study of InP DHBT with antimony-contained base device is of great significance. Technology Computer Aided Design (TCAD) is a base tool for modern research and design of semiconductor devices. As the device size becoming smaller and smaller, until into submicron region, drift diffusion model can’t be correctly used to describe carrier transport processes in the device. In this article, the current density and energy flow density expression of electrons and holes, used for non-local effect in energy balance model and hydrodynamic Model of Silvaco/Atlas device simulator, are deduced from boltzmann transport equation under the relaxation time approximation. For several given two-dimensional InP DHBT with antimony-contained base device, the device performances are analyzed based on several models in this simulator and the following results are obtained:(1) The results of comparsion analysis for the four different models used to model InP/GaAs0.51Sb0.49/InP DHBT device with a50nm thickness base show that, for this size device, the non-local effect should be included in the numerical calculation. The drift diffusion model can’t be correctly used to describe the internal physical mechanism of the device. The carrier scattering mechanism within the Devices has a great influence on device performance.(2) Based on the isothermal energy balance model, the performance of InP/GaAs0.51Sb0.49/InP DHBT with InGaP graded emitter junction is studied. The results show that the InP/GaAs0.51Sb0.49/InP DHBT device with InGaP graded junction present higher current gain, larger collector output current and higher cut-off frequency than abrupt junction InP/GaAs0.51Sb0.49/InP DHBT device.(3) Based on the nonisothermal energy balance model, the effects of four different types of As composition gradient across the base of InP/InGaP/GaAsSb/InP double heterojunction bipolar transistor (DHBT) on the thermoelectrical characteristics are investigated. The results show that the current gain and cut-off frequency are improved due to the introduction of As composition gradient, while the temperature is also raised. The increasing rates of current gain and temperature are higher with a larger percentage range of As composition, while the increasing rate of cut-off frequency is lower. The device with the percentage of As=0.57-0.45from emitter side to collector side have a relative high current gain, cut-off frequency and low bulk temperature, which presents a good trade-off among current gain and cut-off frequency as well as bulk temperature distribution.(4) Based on the isothermal energy balance model, the electrical characteristic of InP/In0.24Ga0.76As0.73Sb0.27/InGaAs DHBT is studied. The results shows that the emitter junction turn on voltage and collector-emitter offset voltage are small. The device has a good common emitter output characteristic, high cut-off frequency and a good collector-emitter breakdown characteristic.