Thermal-Assisted Vertical Electron Injections in Few-Layer Pyramidal-Structured MoS2 Crystals.

Abstract

The interlayer screening effects and charge conduction mechanisms in atomically thin two-dimensional (2D) materials are crucial for electronics and optoelectronics applications. However, such effects remain largely unexplored in chemical vapor deposition (CVD)-grown molybdenum disulfide (MoS2) crystals. Here, we report a controllable CVD-grown monolayer MoS2 and layer-by-layer pyramidal-structured MoS2 crystals with an oxidized Mo foil precursor. The interlayer screening effects and charge conduction mechanisms in the pyramidal-structured MoS2 crystals are studied. Although the Fowler-Nordheim (FN) tunneling model is widely adopted to describe the vertical charge transport mechanism at the 2D semiconductor/bulk metal interface, we found that such a mechanism cannot satisfactorily explain the electrical measurement obtained from our CVD-grown MoS2 samples. Instead, our analysis reveals that Richardson-Schottky (RS) emission is the dominant transport mechanism when Vbias < 1 V. Our findings provide a fundamental understanding of the charge conduction mechanism in CVD-grown MoS2 crystals, which is crucial for development of MoS2 electronics and optoelectronics devices.