GaIn(As)P-GaAs Very Long Wavelength QWIP
Final technical rept. Jul 1997-Jun 2000
NORTHWESTERN UNIV EVANSTON IL CENTER FOR QUANTUM DEVICES
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A majority of infrared sensors used for imaging arrays operating in the long-wavelength infrared region between Lambda 8-12 micrometers are based on HgCdTe. This material system structural difficulties due to poor uniformity, high defect densities, and weak bond strengths that cause difficulties in manufacturing large infrared focal plane array cameras. As an alternative, quantum well infrared photodetectors QWIPs utilizing intersubband absorption between GaAs wells and AlGaAs barriers were perfected. These QWIPs possess better uniformity in comparison to HgCdTe detectors, and QWIP imaging arrays have recently become commercially available. However, the responsivity of GaAsAlGaAs QWIPs is still lower than HgCdTe detectors. In order to further improve the responsivity of QWIP detectors, the development of QWIPs with wells or barriers of GaInAsP instead of AlGaAs has been developed. Results of detector characterization are presented for QWIPs fabricated from a variety of III-V material systems including GaAsGaInP, GaInAsInP, AlGaInAsInP, and GaInAsAlInAs. These material systems extend the range of sensitivity from 3-20 micrometers while remaining lattice-matched to InP. Also, lattice-matched multispectral detectors are demonstrated for sensitivity at both 4 micrometers and 8.5 micrometers. The ultimate objective is to produce a monolithically integrated QWIP focal plane array on Si substrate.
- Optical Detection and Detectors