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 μm and 8-10 μm windows, with peak detectivities at ~4 μm and 9 μm, 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