ALD Encapsulation of CVD WS2 for Stable and High-Performance FET Devices

Processing and characterization of double gate CVD WS2 devices are presented in this work. By combining H2 plasma cleaning and trimethylaluminium (TMA) soak initiated ALD process, double gate (DG) WS2 devices with clean and high-quality interface is obtained, leading to significant improvement in hysteresis and mobility as compared with uncapped devices. Double gate modulation is demonstrated, showing enhanced gate control and better $\mathrm{I}_{\text{on}}$ as compared with single gate operation.