Large Lateral Photovoltage Observed in MoS₂ Thickness-Modulated ITO/MoS₂/p-Si Heterojunctions

Molybdenum disulfide (MoS₂), as a typical two-dimensional (2D) material, has attracted extensive attention in recent years because of its fascinating optical and electric properties. However, the applications of MoS₂ have been mainly in photovoltaic devices, field-effect transistors, photodetectors, and gas sensors. Here, it is demonstrated that MoS₂ can be found another important application in position sensitive detector (PSD) based on lateral photovoltaic effect (LPE) in it. The ITO/MoS₂(3, 5, 7, 9, 10, 20, 50, 100 nm)/p-Si heterojunctions were successfully prepared with vertically standing nanosheet structure of MoS₂. Because of the special structure and the strong light absorption of the relatively thick MoS₂ film, the ITO/MoS₂/p-Si heterojunction exhibits an abnormal thickness-dependent LPE, which can be ascribed to the n- to p-type transformation of MoS₂. Moreover, the LPE of ITO/MoS₂/p-Si structure improves greatly because of forward enhanced built-in field by type transformation in a wide spectrum response ranging from visible to near-infrared, especially the noticeable improvement in infrared region, indicating its great potential application in infrared PSDs. This work not only suggest that the ITO/MoS₂/p-Si heterojunction shows great potential in LPE-based sensors, but also unveils the importance of type transformation of MoS₂ in MoS₂-based photoelectric devices besides strong light absorption and suitable bandgap.