A modified CVD method for the synthesis of monolayer MoS₂and photoelectric improvement by HfO₂passivation

Molybdenum disulfide (MoS₂) is an emerging class of new materials with a wide range of potential practical applications. However, the uncontrollability of monolayer MoS₂synthesized by traditional chemical vapor deposition method and the low responsivity of MoS₂photodetectors limit its further development in the field of photoelectric detection. To achieve controlled growth of monolayer MoS₂and construct MoS₂photodetectors with a high responsivity, we propose a novel single crystal growth strategy of high-quality MoS₂by controlling the Mo to S vapor ratio near the substrate, and deposit a layer of hafnium oxide (HfO₂) on the surface of MoS₂to enhance the performance of the pristine metal-semiconductor-metal structure photodetector. At a reverse bias of 8 V, the HfO₂passivated MoS₂photodetector features an extremely high responsivity of1201AW-1,a response time of around 0.5 s, and a detectivity of7.7×1011Jones.Meanwhile, we deeply investigate the effect of the HfO₂layer on the performance of the fabricated MoS₂photodetector and propose a physical mechanism to interpret the obtained experiment results. These results might facilitate a better understanding on the performance modulation of the MoS₂photodetectors and accelerate the development of MoS₂-based optoelectronic devices.