High-Responsivity Multilayer MoSe₂ Phototransistors with Fast Response Time

There is a great interest in phototransistors based on transition metal dichalcogenides because of their interesting optoelectronic properties. However, most emphasis has been put on MoS₂ and little attention has been given to MoSe₂, which has higher optical absorbance. Here, we present a compelling case for multilayer MoSe₂ phototransistors fabricated in a bottom-gate thin-film transistor configuration on SiO₂/Si substrates. Under 650-nm-laser, our MoSe₂ phototransistor exhibited the best performance among MoSe₂ phototransistors in literature, including the highest responsivity (1.4 × 10⁵ AW⁻¹), the highest specific detectivity (5.5 × 10¹³ jones), and the fastest response time (1.7 ms). We also present a qualitative model to describe the device operation based on the combination of photoconductive and photogating effects. These results demonstrate the feasibility of achieving high performance in multilayer MoSe₂ phototransistors, suggesting the possibility of further enhancement in the performance of MoSe₂ phototransistors with proper device engineering.