High-performance MoO_x/n-Si heterojunction NIR photodetector with aluminum oxide as a tunneling passivation interlayer

The most effective and potential approach to improve the performance of heterojunction photodetectors is to obtain favorable interfacial passivation by adding an insertion layer. In this paper, MoO_x/Al₂O₃/n-Si heterojunction photodetectors with excellent photocurrents, responsivity and detectivity were fabricated, in which alumina acts as a tunneling passivation layer. By optimizing the post-annealing treatment temperature of the MoO_x and the thickness of the ultra-thin Al₂O₃, the photodetector achieved a ratio of photocurrent to dark current of 3.1 × 10⁵, a photoresponsivity of 7.11 A W⁻¹ (@980 nm) and a detective of 9.85 × 10¹² Jones at −5 V bias. Besides, a self-driven response of 0.17 A W⁻¹ and a high photocurrent/dark current ratio of 2.07 × 10⁴ were obtained. The result demonstrated that optimizing the interface of heterojunctions is a promising way to obtain a heterojunction photodetector with high-performance. (paper)