A highly efficient bilayer graphene/ZnO/silicon nanowire based heterojunction photodetector with broadband spectral response

Abstract

This paper presents three self-powered photodetectors namely, p⁺-bilayer graphene (BLG)/n⁺-ZnO nanowires (NWs), p⁺-BLG/n⁺-Si NWs/p^--Si and p⁺-BLG/n⁺-ZnO NWs/p^--Si. The Silvaco Atlas TCAD software is utilized to characterize the optoelectronic properties of all the devices and is validated by analytical modeling. The proposed dual-junction photodetectors cover broadband spectral response varying from ultraviolet to near-infrared wavelengths. The dual-heterojunction broadband photodetector exhibits photocurrent switching with the rise and fall time of 1.48 and 1.27 ns, respectively. At -0.5 V bias, the highest external quantum efficiency, photocurrent responsivity, specific detectivity, and the lowest noise equivalent power of 71%, 0.28 A W^-1, 4.2 × 10¹² cmHz^1/2 W^-1, and 2.59 × 10^-17 W, respectively, are found for the dual-heterojunction device with a wavelength of 480 nm at 300 K. The proposed nanowires based photodetectors offer great potential to be utilized as next-generation optoelectronic devices.