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

• Published in: Ceramics international Vol. 47; no. 2; pp. 1785 - 1791
• Main Authors: Huang, Chun-Ying, Chen, Kuan-Chieh, Chang, Chih-Jung
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.01.2021
• Subjects: Metal-semiconductor-metal; Self-powered; UV photodetector; UV-Assisted thermal annealing; ZnSnO; UV photodetector; Self-powered; UV-Assisted thermal annealing; ZnSnO; Metal-semiconductor-metal
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2020.09.004

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/cm2). 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.