WSe_2/WO_x Heterostructure Growth Via Laser Irradiation with a Metal Absorption Layer

摘要

Recently, two-dimensional materials are considered as potential materials for future electronic devices. Moreover, fabrication of two-dimensional heterojunction attract lots of attention. Here, we use a laser with metal-assisted oxidation method to construct WSe_2/WO_3 heterostructure. In the experiment, a plasma-assisted chemical vapor reduction (PACVR) process was applied to synthesis large area WSe_2 layer. A layer of nickel metal was deposited as a first layer which will absorb the heat of laser and oxidize the top WSe_2 layer, then a additional oxide layer was deposited between nickel layer and WSe_2 layer to prevent the nickel metal layer from getting selenized when we used PACVR process to selenize the amorphous WO_3 precursor. In the laser oxidation process, we choose 808 nm wavelength continuous wave laser as the laser source which will not absorb by WSe_2 layer cause the laser energy is lower than bandgap of WSe_2. Therefore, the nickel metal layer will absorb most of the laser energy then heat the top WSe_2 layer under atmosphere. The top area of WSe_2 heated by the metal layer will get oxidized into WO_3 hence formed a heterojunction with the outer area which was not expose by laser. We also used photolithography to get different pattern of nickel layer which could control and limit the oxidized area by the metal layer but not by the laser exposure area. After the laser oxidation process, this WSe_2/WO_3 structure was further fabricated into photodetector showed its great possibility in future electronic applications.