Low frequency conductance voltage analysis of Si/Ge/sub x/Si/sub 1-x//Si heterojunction bipolar transistors

Low-frequency-conductance-voltage (LFGV) method for analysis of heterojunction bipolar transistors (HBTs) is presented. The method gives accurate quantitative values for the important minority-carrier transport parameters that underlie the transistor performance, such as the base diffusion length, lifetime, diffusion coefficient and transit time. The method also allows a detailed analysis of the current gain and emitter injection efficiency. The analytical model and experimental methodology are demonstrated for a Si/Ge/sub x/Si/sub 1-x//Si HBT with a trapeziodal and linearly graded Ge profiles in the base. The LFGV method is general and can be applied to other bipolar transistors, including those based on III-V materials.