Abstract
Transition-metal Dichalcogenides (TMDCs) collectively name a series of two - dimensional materials, composed of transition metal groups and chalcogenides in the periodic table; one of such materials are: tungsten diselenide (WSe2), molybdenum disulfide (MoS2). These materials have semiconducting properties, have shown atomic-scale thickness, direct band gap, high transmittance and flexibility, etc. Besides these properties, TMDCs have shown outstanding performance in both electrical and optical fields of study. In the past, the most popular way to synthesize TMDCs was to mechanically exfoliate each material. This method provides the least time to get material but at the cost of hard to control thickness and location for the targeted material, thus proving difficult for device fabrication. In view of this, in this work we have decided to use a Chemical Vapor Deposition (CVD) system to synthesize semiconducting WSe2 so that thickness, deposition locations, and quality are adequately controlled. In addition, we have also developed a new low temperature Optical Ablation Method that can precisely ablate 2D materials layer by layer; as such we can adopt this method to achieve clean and fast lithography for larger areas. Last but not least, we will focus on the electrical and optical characteristics of WSe2, by fabricating it into a back-gate structure field-effect transistor and measuring its electrical properties, using a 514 nm wavelength Ar$^+$ laser as source to irradiate the device channel and observe its photoelectrical response, obtaining a photoresponsivity up to 2.88 mAW-1. From the results of electrical measurements, a mobility of up to 6 cm2/V‧s, and subthreshold swing is 203 mV/dec.