Fabrication and characterization of Ge/graphene heterojunction on a flexible polyimide substrate

Abstract

To fabricate a flexible near-infrared (NIR) photodetector, the Ge/graphene (Ge/Gr) heterojunction was fabricated by using pulsed laser deposition on copper-supported graphene, and then the heterojunction was transferred onto flexible polyimide (PI) substrate. The Ge/Gr heterostructure grown at 530 °C demonstrates a flat surface and good crystalline quality. Compared with the as-grown Ge/Gr heterojunction on Si substrate, the Raman spectra of the transferred Ge/Gr heterojunction have no significant change, which indicates the successful transfer of the heterojunction. The Ge/Gr heterojunction has significantly enhanced absorption characteristics in the VIS-NIR range, exhibits rectification ratio up to 13.5 at ± 3 V and stable photoresponse to the NIR light at zero voltage bias.