Abstract
The responsivities of bound-to-bound transitions in an n-type Al0.15Ga0.85As/GaAs/In0.15Ga0.85As multiple-quantum-well infrared photodetector had been measured, using both the 45 degrees facet edge coupling scheme as well as direct back side illumination. It was found that the transverse electric (TE) mode responsivity was slightly redshifted in the 9 mum spectral region, and its magnitude was about 1%, with respect to the mixed TE and transverse magnetic (TM) mode infrared radiation, when direct back side illumination was employed. These observations were in good agreement with theoretical calculations using a 14-band k.p model. The much larger TE response observed when the 45 degrees facet edge coupling scheme was employed was probably due to mesa edge scattering. (C) 2002 American Institute of Physics.