Comparison of MoS2/p-GaN Heterostructures Fabricated via Direct Chemical Vapor Deposition and Transfer Method

Herein, the fabrication of MoS2/p-GaN heterostructures via direct chemical vapor deposition (CVD) and transfer methods are demonstrated. The molybdenum disulfide (MoS2) layers are grown on p-GaN and sapphire substrates via CVD under the same growth conditions. Subsequently, in the case of sapphire substrate, MoS2 from the sapphire substrate is transferred onto the p-GaN substrates to produce a vertically stacked heterostructure. Atomic force microscopy (AFM) images indicate that the MoS2 that is directly grown on the GaN substrate exhibits granular structure, whereas the transferred MoS2 exhibits triangle-shaped grains. In the current-voltage measurement of the heterostructures, similar I-V curves are obtained for the direct CVD and transfer methods. However, the results indicate higher current in the transfer-produced heterostructure than in the CVD-produced heterostructure. The difference in resistance in both heterostructures is attributed to the density of the grain boundary of MoS2. The results suggest that the type of substrate is crucial and the quality of the MoS2 layers depends on them.