Comprehensive Studies of High-Linearity Position-Sensitivity Detectors With Theoretical Consideration on Lateral Photovoltaic Currents

Abstract

Detective properties of a GaAs-based position sensitive detector (PSD) employing a very thin, highly doped p +-GaAs layer as a resistive layer were investigated. In addition to photovoltaic voltages, photovoltaic currents from a three-terminal PSD with two lateral electrodes and one transverse common electrode were also studied. In particular, lateral photovoltaic currents flowing into the two lateral electrodes and/or their differential values, instead of transverse photovoltaic currents were used as output signals. To do so, a PSD itself without power supply was proposed to realize its suitability for applications. When a 2 mW 638 nm light spot was used as an input, a position sensitivity of 38.5 µA/mm, a correlation coefficient (or linearity) of > 0.999, and a nonlinearity (or position error) of 1.25% were obtained for our GaAs-based PSD with a long distance of 14 mm between two lateral electrodes. Besides, an equivalent circuit with a point solar cell was proposed to successfully explain these photovoltaic currents found in various configured 2-terminal and 3-terminal PSDs.

Lateral photovoltaic effect based on novel materials and external modulations

“…However, this strategy is adverse to developing self-powered high-performance photodetectors, which are urgently needed in the current age of information and intelligence. Fortunately, besides longitudinal transport, there is also transverse diffusion of photogenerated carriers [23,24]. More importantly, the diffusion process can be independent of external bias, indicating its great potential application in highperformance devices.…”

“…More importantly, compared with the longitudinal transportation of carriers in traditional photodetectors, the lateral diffusion can work well under no external bias, and the lateral diffusion current is independent of the strength of the bias, which is very different from the longitudinal drift current. Therefore, it is also predicted to be utilized to develop self-powered high-performance photodetectors [24,25].…”