Photovoltaic effect-driven IR response of heterojunctions obtained by direct CVD synthesis of MoS2 nanolayers on crystalline silicon

Abstract

The development of technologies of hybrid structures with combined three-dimensional (3D) and two-dimensional (2D) materials is being recognised as a highly attractive opportunity to create new optoelectronic devices with unique properties originating from the atomic thin structures. In the present study, a novel approach in the direct synthesis of MoS2 2D-layers on p-Si was proved to be acceptable for fabricating a photovoltaic effect–driven photodetector based on a hybrid 2D/3D heterojunction that included an atomically thin n-MoS2 film and crystalline p-Si substrate. It was demonstrated experimentally that the heterojunction with the top and bottom contacts was highly sensitive to illumination between 650 and 1200 nm. The experimental study proved that the response to light was originated by the photovoltaic effect in the sample devices without an external power supply. The maximum sensitivity of the 2D/3D heterostructures to the optical power of the illumination was up to 210 V W−1 and was practically independent of the wavelength. The analysis of experimental I–V, C-V characteristics, Raman spectra and AFM surface images allowed us to construct a flat band model of the hybrid 2D/3D n-p-heterojunction that explained the electrical properties of the n-MoS2/p-Si photodetectors. The photovoltaic effect-driven light detectors offer highly promising possibilities in the development of autonomous photonic systems.