Design and optimization of GaAs/AlGaAs heterojunction infrared detectors

Design, modeling, and optimization principles for GaAs/AlGaAs heterojunction interfacial workfunction internal photoemission (HEIWIP) infrared detectors for a broad spectral region are presented. Both n-type and p-type detectors with a single emitter or multiemitters, grown on doped and undoped substrates are considered. It is shown that the absorption, and therefore responsivity, can be increased by optimizing the device design. Both the position and the strength of the responsivity peaks can be tailored by varying device parameters such as doping and the thickness. By utilizing a resonant cavity architecture, the effect of a buffer layer on the response is discussed. Model results, which are in good agreement with the experimental results, predict an optimized design for a detector with a peak response of 9 A/W at 26 mum with a zero response threshold wavelength lambda(0)=100 mum. For a lambda(0)=15 mum HEIWIP detector, background limited performance temperature (BLIP temperature), for 180degrees field of view (FOV) is expected around 80 K. For a lambda(0)=70 mum optimized design, a highly doped n-type substrate could increase the peak detectivity from 1.7x10(10) to 3.4x10(10) Jones at a FOV=180degrees operated at temperatures below T<T-BLIP=13 K. Intrinsic response times on the order of picoseconds are expected for these detectors. (C) 2004 American Institute of Physics.