Photocurrent Measurements on Novel Group IV Semiconductor Alloys

A system was developed for measuring photocurrent as a function of incident power and wavelength in new Ge$_{1-y}$Sn$_{y}$ semiconductor alloys. Detectors based on this material are expected to operate at wavelengths longer than possible in Ge-detectors due to the lowering of the band gap induced by Sn. Photocurrent measurements were taken on several alloys with incident light at 1.55 $\mu$m for a large range of intensities. Additionally, the absorption coefficient of these samples was determined as a function of wavelength.