A novel position-sensitive detector based on metal-oxide-semiconductor structures of Co-SiO₂-Si

Position-sensitive detectors (PSDs) founded on p-n junctions or metal-semiconductor (MS) junctions have been studied for many decades. This work reports a novel PSD based on Co-SiO₂-Si metal-oxide-semiconductor (MOS) structures. Different from the traditional MS devices where the results were mostly obtained at a given surface (semiconductor side), our MOS devices show better results for both the metal and semiconductor sides (the corresponding measurement methods are referred to as the obverse mode and the reverse mode). We systematically investigated the topographies of Co films, the transverse Schottky barrier (SB) I-V characteristics, and the Co film, thickness dependence of the position sensitivities measured in both modes. The maximum, sensitivities, which occurred at 28 Å, are 42.64 and 51.98 mV mm ^-1 for the obverse and reverse modes, respectively. The highest sensitivities measured in both modes are much larger than those of the classical MS devices and this can be attributed to the thin insulating SiO₂ layer between the Co film, and the Si substrate. The position sensitivity measured in the obverse mode decreases greatly with increasing Co film thickness. We explain this by the shorting effect of the metallic film.