Realization of High-Performance Photoresponsivity of Sb₂Se₃-Based Phototransistors by Using Hybrid Structure and Optimizing Annealing Temperature

Antimony selenide (Sb₂Se₃) is attracting attention as a candidate material with a high potential for photodetection due to its high absorption coefficient and excellent stability compared to other light-absorbing materials. However, Sb₂Se₃-based photodetectors are found to yield rather low responsivity in the visible and near-infrared regions. Herein, the hybrid structure of ZnON/Sb₂Se₃ is for the first time adopted to increase the performance of Sb₂Se₃-based phototransistors. It is shown that ZnON with high mobility enhances the photoresponse by promoting the recirculation of photocarriers. The (Sb₄Se₆)_n ribbons of Sb₂Se₃ are found to be vertically oriented when annealed at 200 °C, inducing photocarriers to ZnON more easily than laterally oriented ribbons. The 200 °C-annealed phototransistors give high responsivity of 2.14 × 10⁴ A/W⁻¹ (650 nm) and 2.47 × 10⁴ A/W (905 nm), the latter being the highest among Sb₂Se₃-based photodetectors. Further, the 200 °C-annealed phototransistors exhibit superb stability, showing over 92% of the initial responsivity and over 81% detectivity even after being exposed to air for 5 weeks without passivation. It is further shown that the optimal devices reveal remarkably stable detectivity of 4.76 × 10¹³ Jones and 5.95 × 10¹³ Jones for 650 nm and 905 nm light, respectively.