High-sensitivity position-sensitive detectors to low-power light spots

This work reported on detecting properties of a p+-i-n+ position-sensitive detector (PSD) which has a thin heavily-doped p+-GaAs layer and a thick lightly-doped i-GaAs layer as a resistive layer and an optical absorption layer, respectively. Two lateral electrodes on the p+-GaAs layer were separated by a distance of 12 mm to provide lateral photovoltaic voltages. The p+-GaAs layer with a small resistivity produces a long diffusion length for excess holes. Thus, a high linearity of > 99.8 % and a detection error of