A waveguide-integrated SnSe photodetector on a lithium niobate thin film with high responsivity, fast response, and self-powered capability

Abstract

Photodetectors based on two-dimensional materials offer great potential for photonic integration due to their high responsivity, fast response time, and broad wavelength sensitivity. In this study, we presented a waveguide-integrated SnSe photodetector on a lithium niobate on insulator platform, fabricated using mechanical exfoliation and dry transfer methods. The SnSe flake compensated for the low electrical conductivity and inefficient photoelectric conversion of lithium niobate. Under a 1 V bias, the photodetector achieved a high responsivity of 153 000 mA W⁻¹ and response/recovery times of 0.06/2.77 ms at a wavelength of 0.85 μm. At 1.55 μm, it demonstrated a responsivity of 82.7 mA W⁻¹ with response/recovery times of 0.21/1.71 ms. The photodetector exhibited a detectivity of 4.8 × 10¹⁰ cm Hz^0.5 W⁻¹ at 0.85 μm and 1.8 × 10⁷ cm Hz^0.5 W⁻¹ at 1.55 μm under a 1 V bias. In addition to biased operation, the device also worked at 0 V, showing a clear on/off photocurrent at 0.85 μm with ∼0.13/0.13 ms response/recovery times. This self-powered response originated from the asymmetric Au/SnSe Schottky contacts at the two electrodes. These results open new possibilities for achieving high-performance SnSe photodetectors and their application in integrated photonic technologies.