A CdS-Si photodetector for integrated optics

Photodetectors based on nCdS-pSi heterojunctions and operated in both photovoltaic and photoconductive models, have been integrated with planar optical waveguides. The detector structure consisted of a 7059 glass waveguide which was terminated over the nCd-pSi junction. Prism couplers and directional coupling action between a ribbon fibre and the glass film have been used to launch light into the waveguides. A maximum responsivity of 1mV·μW^-1 was recorded at 633 nm with the diode operating in the photovoltaic mode and 0.06μA·μW^-1, corresponding to a quantum efficiency of 12%, in the photoconductive mode.