This QWIP remains background limited up to a detector temperature of 100 K for biases between −7.5 V and +2.5 V. Compared with the GaAs/GaInP QWIP reported in the last section, the peak wavelength increased slightly. The photoresponse has a peak around 4 μm with broad maxima. Such asymmetry could be related to either a structural difference in the two quantum well interfaces or to dopant migration during the material growth. This arises from an asymmetric quantum well potential profile. 72 The effect of the quaternary alloy was to reduce the valence band offset relative to lattice matched GaAs and thus increase the cut-off wavelength.Ī photovoltaic effect is observed from the photoresponse curve (see Figure 1 in reference 72). In 0.29As 0.39P 0.61 QWIP was grown by LP-MOCVD with 50 periods of 30 Å wide GaAs quantum wells separated by 280 Å wide GaInAsP (Eg = 1.8 eV at T=300 K) barriers. To increase the cut-off wavelength, a lattice-matched GaAs/Ga 0.71.
Razeghi, in Handbook of Infra-red Detection Technologies, 2002 p-type GaAs/GaInAsP QWIP
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