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.