Self-consistent performance modeling for dualband detectors

Dualband and multiband detectors have generated interest for their ability to measure two very different wavelength bands simultaneously. The dualband detection is achieved by using two different mechanisms to cover the two separate response bands: an interband process for the shorter wavelengths, and free carrier absorption followed by internal photoemission for the longer wavelengths. Previously the two processes have been modeled separately, and a reasonable agreement has been obtained on the spectral shape, although the entire wavelength range has not been covered in a single model. Also, the previous modeling efforts did not give an absolute scale for the response, instead using an experimentally determined gained factor to fix the absolute response. Here a model is presented (which does not use any fitting parameters) which can provide absolute responsivity values and detector performance parameters. By using a Monte Carlo approach including various scattering mechanisms, the carrier transport is modeled giving an absolute value for the dark current and photocurrent. The results are used to predict the spectral response for a GaN/AlGaN UV-IR dual band heterojunction detector. (C) 2008 American Institute of Physics.