Design and characterization of two color GaAs based quantum well infrared detector structures

The choice of detector technology for infrared focal-plane arrays may be influenced by several factors as sensitivity, uniformity, array size, reproducibility, cost and integration possibilities. The material system GaAs/AlGaAs provides several advantages compared to the state-of-the-art II-VI semiconductor detectors, including the mature GaAs growth and processing technologies and the flexibility of energy band tailoring in QW's to operate at different atmospheric transmission windows. In this work we report the detailed design procedure of a tunable two-color photoconductive GaAs/AlAs/AlGaAs and GaAs/AlGaAs stacked Quantum Well Infrared Photodetector (QWIP). The structures are optimized to operate in the 3-5 /spl mu/m and 8-10 /spl mu/m windows, with peak detectivities at /spl sim/4 /spl mu/m and 9 /spl mu/m, respectively. A transfer-matrix method was used to estimate the subband energies of the structures according to the operating wavelength specifications. The effect of many-body corrections was also taken into account.