Broadband (8–14 μm), normal incidence, pseudomorphic GexSi1−x/Si strained-layer infrared photodetector operating between 20 and 77 K

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Abstract
Performance characteristics of a pseudomorphic p‐type, normal incidence, Ge0.25Si0.75/Si strained‐layer quantum well infrared photodetector on (001) Si is described for 20≤T≤77 K. The device shows broadband photoresponse (8–14 μm) which is attributed to strain and quantum confinement induced mixing of heavy, light, and split‐off hole bands. Typical device responsivity at λ=10.8 μm is ∼0.04 A/W over the 20–77 K temperature range. A detectivity D*λ=3.3×109 cm √Hz/W was measured at a bias of −2.4 V for a temperature of 77 K at λ=10.8 μm and no cold shield. Room temperature FTIR measurements yield a quantum efficiency η≊3.1% at λp≊8 μm at 300 K.