MEDIUM-WAVELENGTH, NORMAL-INCIDENCE, P-TYPE SI SIGE QUANTUM-WELL INFRARED PHOTODETECTOR WITH BACKGROUND LIMITED PERFORMANCE UP TO 85 K/

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 mu m with a peak responsivity of R(p) = 76 mA/W, at a peak wavelength of lambda(p) = 5 mu m, resulting in a detectivity as high as D(lambda) = 2 x 10(10) cm root Hz/W at a temp erature of T = 77 K. Background limited infrared performance is achiev ed 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 Lutt inger-Kohn calculation including the in-plane dispersion. (C) 1996 Ame rican Institute of Physics.