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

Abstract

The detector characteristics of a pseudomorphic p‐type Si_0.64Ge_0.36/Si quantum well infrared photodetector are reported. The device exhibits a photoresponse between 3 and 8 μm with a peak responsivity of R_p=76 mA/W, at a peak wavelength of λ_p=5 μm, resulting in a detectivity as high as D_λ^*=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.