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By assembling two isolated monolayers, the vertical stacking heterostructure of SnSe2/MoSe2 is designed. The morphology of the SnSe2/MoSe2 vertical heterostructures is observed by optical microscope and atomic force microscope. Furthermore, through controlling different annealing time at the temperature 150 °C, the promoted field-effect performance of the SnSe2/MoSe2 heterostructures is observed. The underlying mechanism can be attributed to the increasing interlayer coupling along with the extended annealing time. On the other hand, due to the type-II band alignment, the electron will transfer from the MoSe2 to SnSe2, leading to the weaker photoluminescence intensity. The results show that the field-effect performance can be greatly improved via appropriate annealing time, exhibiting great potential application of the SnSe2/MoSe2 heterostructure in optoelectronic devices.

Two-dimensional (2D) semiconductors have been attracting considerable interests for the potential applications in nano-optoelectronic devices. Here, we study the electronic and optical properties of the ZrS2/HfSe2 van der Waals (vdW) heterobilayer, which presents an intrinsic type-II band alignment. The conduction band minimum (CBM) and the valence band maximum (VBM) are separately dominated by the ZrS2 and HfSe2 layers, respectively. More importantly, the superior optical absorption of the heterostructure can be reached to the 106 amounts in ultraviolet region. Our results suggest that the 2D ZrS2/HfSe2 vdW heterobilayer would be likely utilized in the optoelectronic devices.