Self-powered asymmetric Schottky photodetector integrated with thin-film lithium niobate waveguide

Abstract

Thin-film lithium niobate (TFLN) is considered a crucial platform in next-generation integrated optoelectronics due to its excellent optical properties. Photodetectors are essential components for constructing fully functional photonic circuits. However, due to the low electrical conductivity and weak light absorption, TFLN cannot be directly used for fabricating photodetectors. In this study, we proposed and demonstrated a high-performance MoTe₂/TFLN heterostructure integrated Schottky photodetector operating at telecommunication wavelengths (1310 nm and 1550 nm). This structure enhances the photovoltaic effect by bending MoTe₂ at the edge of one electrode, thereby achieving self-powered operation. At a wavelength of 1310 nm, the photodetector achieves a self-powered responsivity of 70 mA/W, which is among the highest for waveguide-integrated photodetectors. Additionally, due to the strong rectification effect of the Schottky junction, the photodetector exhibits an extremely low dark current of only 25 pA at −0.5 V bias voltage. The on/off ratios reach 2.6 × 10⁴ at 0 V and 4.1 × 10⁴ at −0.5 V bias. The self-powered response times were measured, showing fast response and recovery times of 160 μs and 169 μs, respectively.