Realization of a self-powered ZnSnO MSM UV photodetector that uses surface state controlled photovoltaic effect

Self-powered ultraviolet (UV) photodetectors (PDs) that use a vertical p-n junction generally involve a complex fabrication process if they are to be integrated with optoelectronic integrated circuits (OEICs). This study demonstrates the fabrication of a self-powered metal-semiconductor-metal (MSM) UV PD with simple planar structure using nontoxic and earth abundant ZnSnO (ZTO). The self-powering characteristic is realized using a localized UV-assisted thermal annealing (LUV-TA) process that selectively modifies the surface states underneath different contacts and creates asymmetric Schottky barrier heights (SBHs) for the MSM PD. The a-ZTO MSM PD with assymmetric SBHs operates at a zero bias and has a responsivity of 18.2 mA/W at 350 nm. The open-circuit voltage is 0.40 V under UV illumination at a wavelength of 365 nm (50 mW/cm(2)). The device exhibits a fast response speed, with a rise time of 38 ms and a decay time of 180 ms. This study demonstrates that this strategy can be extended to other MSM PDs, particularly those that use an amorphous oxide semiconductor as the active layer.

Automated summary

This study demonstrates the fabrication of a self-powered metal-semiconductor-metal (MSM) UV photodetector with a simple planar structure using nontoxic and earth abundant ZnSnO (ZTO). The device operates at zero bias and has a responsivity of 18.2 mA/W at 350 nm, showing fast response speed and good performance under UV illumination.