Photoelectric Properties of Si-Si_l-xGe_x-Ge Heterostructures for Infrared Detector

Si-Si_l-xGe_x-Ge heterostructures with Ge fraction graded linearly from 1 to 0 have been epitaxially grown on Ge substrates by rapid, thermal process/very low pressure-chemical vapor deposition. The peak value of the spectrum response for these structures ranges from 1.3 to 1.55 μm, which is just in accordance with the optical fiber communication window, and considered to be the superposition of the response in Si_l-xGe_x absorption region and the Ge absorption region. High detecting sensitivity, and low dark current have been achieved from the prototype SiGe ptype intrinsic n-type photodetectors made of these structures.