Photoresponse improvement of mixed-dimensional 1D–2D GaAs photodetectors by incorporating constructive interface states

Abstract

Mixed-dimensional optoelectronic devices bring new challenges and opportunities over the design of conventional low-dimensional devices. In this work, we develop unreported mixed-dimensional GaAs photodetectors by utilizing 1D GaAs nanowires (NWs) and 2D GaAs non-layered sheets (2DNLSs) as active device materials. The fabricated photodetector exhibits a responsivity of 677 A W⁻¹ and a detectivity of 8.69 × 10¹² cm Hz^0.5 W⁻¹ under 532 nm irradiation, which are already much better than those of state-of-the-art low-dimensional GaAs photodetectors. It is found that this unique device structure is capable of converting the notoriously harmful surface states of NWs and 2DNLSs into their constructive interface states, which contribute to the formation of quasi-type-II band structures and electron wells in the device channel for the substantial performance enhancement. More importantly, these interface states are demonstrated to be insensitive to ambient environments, indicating the superior stability of the device. All these results evidently illustrate a simple but effective way to utilize the surface states of nanomaterials to achieve the high-performance photodetectors.