Processing and Characterization of a MOS-Type Tetra Lateral Position Sensitive Detector With Indium Tin Oxide Gate Contact

A 2-D tetra lateral position sensitive detector (PSD) based on the metal-oxide-semiconductor (MOS) principle has been manufactured and characterized. The active area of the device is 5 mm times 5 mm and the intention is to use the central 4 mm times 4 mm for low nonlinearity measurements. The gate contact is made of indium tin oxide (ITO) that is a degenerate electrically conducting semiconductor, which, in addition, is also transparent in the visible part of the spectrum. The use of a MOS structure results in a processing with no necessity to use implantation or diffusion in order to make the resistive p-layer as in a conventional p-n junction lateral effect PSD. Position measurements show good linearity in the middle 4 mm times 4 mm area. Within the middle 2.1 mm times 2.1 mm, the nonlinearity is within plusmn1.7% of the active area with a position detection error of maximum 60 mum. Measured MOS IV characteristics are compared to a level 3 spice model fit and show good agreement. The threshold voltage is determined to be -0.03 V. Responsivity measurements show a high sensitivity in the visible spectral region.