Detailed Analysis on the Spectral Response of InP/InGaAs HPTs for Optoelectronic Applications

We analyze an analytical spectral-response model for heterojunction phototransistors (HPTs) in order to understand the behavior of lattice-matched InPZIn_0.47Ga_0.53As HPTs with changing device and material parameters. The preliminary modeling of the spectral response lead to a good agreement between theoretical and experimental results for incident wavelength radiations at 980, 1310, and 1550 nm. We then performed several simulations in order to determine the individual influences of several parameters, such as the base-layer thickness and the surface-recombination velocity on the responsivity of the device. A decreasing trend for the surface-recombination parameter with increasing wavelengths was observed, and it is attributed to the greater recombination rate for high-energy photons generated near the surface.