Dual-Mode Solar-Blind Ultraviolet Imaging Application Based on <i>β</i> -Ga ₂ O ₃ MSM Photodetector Array

This work presents a 4 × 4 self-powered solar-blind ultraviolet (UV) photodetector (PD) array based on Ga<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> thin films, designed with asymmetric interdigitated electrodes. The device operates effectively without external bias, demonstrating excellent self-powered functionality, with a peak responsivity of 2.45 mA/W at zero bias and a cutoff wavelength of 255 nm. The UV-to-visible light suppression ratio of over three orders of magnitude, indicating high selectivity in the solar-blind wavelength range of the PD. Through band structure analysis, we explained the reason behind the device’s photoresponse under zero external bias. This can be attributed to the variation in the built-in electric field distribution caused by the different widths of the two electrodes. Under UV illumination, the Schottky barrier heights on both sides differ, enabling photogenerated carriers to effectively transport between the electrodes even without an external bias. Moreover, the device shows remarkable uniformity and stability, by utilizing this PD array as an imaging unit, solar-blind imaging was performed in dual modes (self-powered and biased), producing clear images. These results offer an approach and technical reference for the application of Ga<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub>O<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>-based PDs in optical imaging and optoelectronic integration.