Normal incidence hole intersubband quantum well infrared photodetectors in pseudomorphic GexSi1 − x/Si

Abstract The physics underlying normal incidence hole intersubband absorption in p-type semiconductor quantum wells is briefly reviewed. The fabrication and performance characteristics of a pseudomorphic Ge 0.25 Si 0.75 /Si p-type quantum well infrared photodetector on (001)Si are described. These devices show broadband response (8–14 microm) which is attributed to strain and quantum confinement induced mixing of heavy, light and split-off hole bands. Typical responsivity at λ = 10.8 microm is 0.04 A/W over the 20–77 K temperature range. A detectivity D ∗ λ = 3.3 × 10 9 cm Hz > Watt −1 , was measured at bias voltage of -2.4 V, for a temperature of 77 K, λ = 10.8 gmm and no cold-shield (i.e. T cavity = 300 K and an angular field of view θ = 180°). Room temperature FTIR absorption measurements yield a peak absorption coefficient α p = 3914 cm −1 at λ p = 8 microm, corresponding to a quantum efficiency η = 3.1% at 300 K.