Medium-wavelength, normal-incidence, <i>p</i>-type Si/SiGe quantum well infrared photodetector with background limited performance up to 85 K

Abstract

The detector characteristics of a pseudomorphic p-type Si0.64Ge0.36/Si quantum well infrared photodetector are reported. The device exhibits a photoresponse between 3 and 8 μm with a peak responsivity of Rp=76 mA/W, at a peak wavelength of λp=5 μm, resulting in a detectivity as high as Dλ*=2×1010 cm√Hz/W at a temperature of T=77 K. Background limited infrared performance is achieved up to T=85 K. Investigation of the polarization dependence shows that in-plane polarized radiation produces the largest photoresponse, thus making normal-incidence detection feasible. The relevant optical transitions are analyzed on the basis of a self-consistent 6-band Luttinger–Kohn calculation including the in-plane dispersion.