Ultraviolet, visible, and infrared response of PtSi Schottky-barrier detectors operated in the front-illuminated mode

The quantum efficiency of PtSi Schottky-barrier detectors has been measured as a function of wavelength from 0.23 to 7 mu m. For front-illuminated PtSi/p-Si devices operated at low temperatures, quantum efficiencies of 40 to 70% are obtained in the ultraviolet (UV) and visible regions with little loss of the infrared (IR) photoresponse that is obtained for operation in the conventional back-illumination mode. For room-temperature operation of front-illumination PtSi/n-Si devices, the quantum efficiencies are approximately the same in the UV and visible regions, but the IR response decreases abruptly beyond the Si absorption edge. Room-temperature transmission and reflection measurements have been used to determine the values of the real and imaginary parts of the complex dielectric constant for PtSi at wavelengths from 0.2 to 3 mu m. A simple model, used with these values and published values of the dielectric constant for Si, yields calculated quantum efficiencies in the UV and visible regions that agree quite well with the measured efficiencies. The temporal response of front-illuminated PtSi/p-Si detectors in the visible and IR regions is found to be fast enough for operation at video frame rates. >