Van der Waals Integrated LiNbO3/WS2 for High-Performance UV-Vis-NIR Photodetection

Lithium niobate (LN) is widely used in various optoelectronic systems due to its structural anisotropy and ferroelectric feature, which is one of the most essential platforms for next-generation integrated optoelectronics. However, the insulating and optically transparent characteristics of LN have greatly limited the application in photodetection. Here, a high-performance LN/WS2 based photodetector is achieved through a van der Waals integration strategy in which the pyroelectric property of LN and the moderate bandgap of WS2 are well combined. Upon light illumination, the light induced carriers in WS2 would increase and the pyroelectric charges of LN will cross the interfacial gap and asymmetrically inject into the WS2, creating an n(-)/n(+) homojunction, thus improving the on-state current. Under dark conditions, the sudden removal of the laser would introduce an instantaneous enhancement of polarization in the LN lattice, leading to an improved confinement on the remaining carriers in WS2, achieving a lower dark current. In this regard, the configurated device acquires a high on/off ratio more than 10(4) under zero bias, which represents the best among all the reported LN-based photodetectors. This work realizes the complementary integration of 2D materials and ferroelectric LN and provides a feasible way for high-performance photodetectors based on the LN platform.