Scalable Growth of 2D WSe₂ with tungsten and tungsten trioxide films as precursors

Atomically thin 2D tungsten diselenide (WSe₂) layers have drawn much interest due to their remarkable optical properties and potential applications in next-generation optoelectronics and energy harvesting devices [1]. High-quality wafer-scale synthesis of 2D materials is necessary for their practical applications [2]. Herein, we demonstrate a scalable synthesis of WSe₂ layers of controlled thickness using the Chemical vapor deposition (CVD) technique. We have deposited WO₃ and W films on thermally oxidized silicon and sapphire wafers by thermal evaporation and magnetron sputtering respectively. The WO₃ deposited substrates were selenized in an atmospheric pressure CVD reactor at high temperature in the presence of Ar/H₂ mixture. The WSe₂ films synthesized by this process show the characteristic Raman mode at ≈ 250 cm^-1, which is indicative of the out-plane vibration of Se atoms. The WSe₂ films show robust photoconductivity response (PCR). On the other hand, the WSe₂ synthesized from pure tungsten films shows superior surface morphology, PCR and optical response. Further details of the structure, bonding and PCR of these films will be presented at the meeting with a clear objective to establish the advantages and drawbacks of the two selenization processes discussed here.