The mechanism of an a-Ga2O3/MoS2 heterojunction for high-performance self-powered solar-blind photodetection and imaging

Abstract

The development of high-efficiency photoanodes is critical for the large-scale implementation of photoelectrochemical (PEC) devices, while the performance of PEC photoanodes is generally limited by the rapid recombination of photogenerated carriers, low photoconversion efficiency, and poor corrosion resistance. Heterojunctions formed from narrow- and wide-bandgap semiconductors present a promising strategy for developing high-performance photoelectric materials. In this work, we fabricated amorphous Ga₂O₃/MoS₂ (a-Ga₂O₃/MoS₂) heterojunction-based PEC photodetectors by sequentially depositing a-Ga₂O₃ and MoS₂ via magnetron sputtering, followed by a chemical vapor deposition (CVD) vacuum vulcanization process for the formation of a heterojunction. The obtained photodetector exhibited a significantly enhanced photoresponse intensity of 10.83 µA cm⁻² – a 5-fold increase compared to that of pristine a-Ga₂O₃ – along with a faster response time (24 ms versus 51 ms). These enhancements are attributed to a favorable band alignment that facilitates efficient electron transfer in the circuit and hole migration to the solid–fluid interface, coupled with improved carrier separation driven by the built-in electric field. The results presented in this study highlight the significant potential of the a-Ga₂O₃/MoS₂ heterojunction for UV imaging applications. In addition, our preliminary investigations in this direction yielded valuable insights that further support its feasibility.