Sensitized monolayer MoS2 phototransistors with ultrahigh responsivity

Abstract

Monolayer MoS₂ photodetectors have been extensively investigated; however, their responsivity and sensitivity are highly limited due to the monolayer thin profile. Herein, we proposed a sensitized-MoS₂ photodetector consisting of a monolayer MoS₂ transport channel sensitizing with few-layer MoS₂ on top; this photodetector exhibited a very high responsivity of ∼10⁴ A W⁻¹ (at negative V_g) and ∼10⁵–10⁶ A W⁻¹ (at zero and positive V_g) due to improved photon absorption and enhanced mobility, more than one order of magnitude higher than that of the pure monolayer MoS₂. Moreover, the sensitivity D* as high as ∼10¹³ Jones was achieved by operating our sensitized device in the depletion mode, where there was very low noise. This device design and the simple approach proposed herein can open up new ways towards high-performance 2D material-based photodetectors.