One-Step CVD Growth of Monolayer/Multilayer MoS2 Hybrid Structure for Enhanced Photodetection

Abstract Although monolayer MoS2 has been widely explored for optoelectronic applications, its light absorption is largely limited due to its sub-nanometer-scale thickness. In contrast, multilayer MoS2 exhibits strong light absorption, high carrier mobility, and excellent dielectric screening. To enhance the optoelectronic performance of MoS2, the growth of MoS2 heterostructures via chemical vapor deposition (CVD) has been extensively investigated. In this work, monolayer/multilayer MoS2 hybrid structures were grown by one-step CVD using sodium dodecyl sulfate (SDS) as a seed promoter. The SDS was deposited onto SiO2/Si substrates via N2 blow-drying, spin-coating, and ambient drying, yielding samples denoted as SDS-N2-SiO2, SDS-spin-SiO2, and SDS-air-SiO2, respectively. The size, density, and thickness of the resulting MoS2 nanosheets were highly dependent on the amount of SDS present on the substrate. Small-sized monolayer MoS2 nanosheets were obtained on the SDS-N2-SiO2 substrates. On the SDS-spin-SiO2 substrates, the grown MoS2 films consisted of various nanostructures, including monolayer MoS2, multilayer MoS2, and MoS2 nanospirals. On the SDS-air-SiO2 substrates, high-density multilayer MoS2 flakes (∼200 nm in size) were uniformly grown on large monolayer MoS2 nanosheets (several tens of micrometers in size). These multilayer flakes consist of 5 to 9 layers of MoS2 with random stacking orientations. The as-grown hybrid structures were thoroughly characterized using optical microscopy, atomic force microscopy, high-resolution transmission electron microscopy, and Raman spectroscopy. Compared with pristine monolayer MoS2, the hybrid structures exhibited enhanced carrier mobility, photoresponsivity, and photosensitivity by approximately one order of magnitude. Our results indicate that these monolayer/multilayer MoS2 hybrid structures are promising candidates for high-performance optoelectronic devices.