WSe2/WOx Heterostructure Growth Via Laser Irradiation with a Metal Absorption Layer

Abstract

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 WSe2/WO3 heterostructure. In the experiment, a plasma-assisted chemical vapor reduction (PACVR) process was applied to synthesis large area WSe2 layer. A layer of nickel metal was deposited as a first layer which will absorb the heat of laser and oxidize the top WSe2 layer, then a additional oxide layer was deposited between nickel layer and WSe2 layer to prevent the nickel metal layer from getting selenized when we used PACVR process to selenize the amorphous WO3 precursor. In the laser oxidation process, we choose 808 nm wavelength continuous wave laser as the laser source which will not absorb by WSe2 layer cause the laser energy is lower than bandgap of WSe2. Therefore, the nickel metal layer will absorb most of the laser energy then heat the top WSe2 layer under atmosphere. The top area of WSe2 heated by the metal layer will get oxidized into WO3 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 WSe2/WO3 structure was further fabricated into photodetector showed its great possibility in future electronic applications.