Device Perspective on 2D Materials

The rise of two-dimensional (2D) crystals has given new challenges and opportunities to the device research. The semiconducting MoS₂ as n-channel and few-layer phosphorene as p-channel have been considered as promising ultra-thin body channels for future microelectronic and optoelectronic devices. In this paper, we focus on the fundamental device properties of these 2D transistors. In the first part of the paper, we demonstrate high-performance MoS₂ FETs with record drain current of 460 mA/mm and record low contact resistance of 0.5 Ω·mm enabled by molecular chemical doping of 1,2 dichloroethane (DCE). In the second part of the paper, we introduce a new p-type 2D material called phosphorene which is one monolayer of layered black phosphorus (BP). At room temperature, the few-layer phosphorene field-effect transistors with 1.0 μm channel length display a high on-current of 194 mA/mm, a high hole field-effect mobility of 286 cm²/V·s, and an on/off ratio up to 10⁴. We demonstrate the possibility of phosphorene integration by constructing the first 2D CMOS inverter of phosphorene PMOS and MoS₂ NMOS transistors and the first BP/MoS₂ PN diode for photonic applications.