TABLE OF CONTENTS The main purpose of this chapter was to discuss the physical models necessary for simulation of advanced heterostructure devices, such as HBTs or HEMTs. Important material parameters of strained-SiGe have been considered. Comprehensive analytical models for material parameter of strained-SiGe films have been presented. The model equations account for valence band discontinuity, heavy doping effects, valence and conduction band effective densities of states and ionised doping concentration. Minority and majority electron and hole mobilities in the whole range from low to very high electric field have also been discussed in detail. The models are based on computed and experimental data available in the literature. SiGe material parameter models developed can be incorporated in commercially available simulators for simulation of SiGe HBTs. New models for physical properties with respect to material composition and strain conditions owing to lattice mismatch have to be developed.
For advanced heterostructure simulations, anisotropic effective carrier masses, density of states and carrier mobilities should be considered. A built-in feature for automatic estimation of the strain condition based on empirical relation for the growth-condition-dependent critical layer thickness may also be developed. Possible simulation applications in the future could be the simulation of leakage currents at low bias in GaAs-based HBTs, breakdown simulation in III V devices and thermal investigations not only in the device but also in the interconnects. The accuracy of the device simulation for all devices has to be verified not only against d.c. but also against RF measurements.
The big challenge remaining for III V...
