Multiband infrared detectors based on III-V materials

Abstract

Infrared detector technology based on intersubband absorption in III-V materials has shown remarkable success in advancing low-cost, highly uniform, high-operability, large-format focal plane arrays (FPAs). It also permits vertical integration of detector stacks to create multi-band or tunable FPAs. Each detector stack of multi-quantum well layers absorbs photons within the specified wavelength band, allowing other photons to transmit through permitting multiband detection. The wavelength of the peak response and cutoff can be continuously tailored by varying layer thickness (well width), barrier composition (barrier height), and carrier density (well-doping density). The GaAs/Al x Ga 1-x As material system allows the quantum well parameters to be varied over a range wide enough to enable light detection at any wavelength range from 6 to 20 μm. By adding a few monolayers of In y Ga 1-y As during the GaAs quantum well growth, the short wavelength limit can be extended to 3 μm. The spectral bandwidth of these detectors can be tuned from narrow (Δλ/λ ~ 10%) to wide (Δλ/λ ~ 40%), according to application requirements. Multi-band detector technology can be extended to near IR or visible wavelengths by adding detector layers utilizing interband absorption in these materials.