A practical theoretical model for Ge-like epitaxial diodes. II. Matching the experimental optical responsivity in <i>pin</i> devices

A theoretical model that can be used to simultaneously fit the I–V characteristics and spectral optical responsivity of Ge-like pin diodes is described in detail and validated experimentally using specially fabricated Ge- and Ge1−ySny devices. The model combines a numerical solution of the basic semiconductor transport equations with a rigorous calculation of the optical generation rate that accounts for multiple reflections in the device structure multilayers. The results can be used to quantify the reduction of photocurrent associated with recombination centers for full optimization of the device structure.