Modeling of steady-state optical phenomena in transistors and diodes

A lumped model is derived for photodiodes and phototransistors from which steady-state spectral properties, such as quantum efficiency, can be determined. The model is derived in a manner such that its utility extends to regions of any length ω that is, there is no
\omega/L\ll1
restriction, where
L
represents the minority-carrier diffusion length in the region. The validity of the resulting model is demonstrated by showing that the lumped model predicts the empirically measured quantum efficiency of planar photodiodes to within 10 percent.