Monolithic green-sensitive photodetectors enabled by a ZnSnN₂/GaN nanorods/silicon double heterojunction

Single heterojunction-based photodetectors (PDs) have been regarded as attractive optical devices due to their outstanding electrical and optical properties (carrier density, operation speed, and bandgap engineering). However, there are significant challenges associated with single heterojunction-based PDs, especially nanorods/film junctions, including low responsivity (R), external quantum efficiency (EQE), and wavelength selectivity. Herein, a monolithic green-sensitive double heterojunction PD (DH-PD) was demonstrated by a ZTN/GaN NRs/Si-based 3D/2D stacking structure. The optimized ZTN thin-film was directly deposited onto the top surface of the GaN NRs/Si template to realize a double heterogenous junction. The DH-PD showed high wavelength selectivity under green light, with an R of 3.3 mA W⁻¹ and EQE of 0.77%, which were superior properties compared to the single heterojunction PD (SH-PD).