Self-Powered, Broadband (400–1800 Nm), Highly Responsive Photodetectors Based on Germanium Micropillars/Cu2-ZnSnS4 Heterojunctions

This study deals with the fabrication of germanium (Ge) micropillars (MPs) followed by their development into novel Ge-MPs/Cu
2
ZnSnS
4
(CZTS) heterojunction-based photodetectors. Vertically oriented and uniform Ge MPs templates were fabricated using facile and cost-effective wet-chemical etching techniques at the wafer scale. The CZTS thin films were deposited by pulsed laser deposition technique on MPs to obtain Ge MPs/CZTS heterostructures. Scanning electron microscopy and atomic force microscopy have been carried out to study the morphologies of the as-grown conical-shaped Ge MPs and their heterostructure with CZTS. The fabricated Ge MPs/CZTS heterostructure was then developed into a self-powered photodetector exhibiting broadband photodetection characteristics covering a wavelength range from visible-near infrared to short wave infrared (Vis-NIR-SWIR) region.