Fabrication and characterization of SiC/Ge/graphene heterojunction with Ge micro-nano structures

To widen the detection wavelength range and improve the detection sensitivity of SiC-based optoelectronic devices, the SiC/Ge/graphene heterojunction was fabricated by using wet transfer of the graphene following chemical vapor deposition. The Ge films on 4H-SiC(0001) have polycrystalline structure with nano-wire (NWs) and submicron spherical island (SIs) features. Due to the distinct light trapping effect of the Ge NWs, the SiC/GeNWs/graphene heterojunction has an absorbance of more than 90% in the 500-1600 nm range, which is higher than the SiC/GeSIs/graphene heterojunction. And the SiC/GeNWs/graphene heterojunction photodetector exhibits rectification ratio up to 25 at ±2 V and stable photoresponse to the NIR light at zero voltage bias.