Heterojunction bipolar transistor with diffusive and ballistic electron transport in the base

The effect of ballistic transport in the base of the heterojunction bipolar transistor is treated by the modification of the boundary conditions of the standard diffusion equation. The transistor properties are characterised by the y/sub ij/ and h/sub ij/ parameters that are considered as functions of signal frequency and base length. The pure ballistic and pure diffusive electron transport is considered as a special case.