High Current Density in Monolayer MoS${}_2$ Doped by AlO${}_x$

Abstract

Semiconductors require stable doping for applications in transistors, optoelectronics, and thermoelectrics. However, this has been challenging for two-dimensional (2D) materials, where existing approaches are either incompatible with conventional semiconductor processing or introduce time-dependent, hysteretic behavior. Here we show that low temperature (< 200${}^{\circ }$ C) sub-stoichiometric AlO${}_x$ provides a stable n-doping layer for monolayer MoS${}_2$, compatible with circuit integration. This approach achieves carrier densities > 2x10${}^{13}$ 1/cm${}^2$, sheet resistance as low as ~7 kOhm/sq, and good contact resistance ~480 Ohm.um in transistors from monolayer MoS${}_2$ grown by chemical vapor deposition. We also reach record current density of nearly 700 uA/um (>110 MA/cm${}^2$) in this three-atom-thick semiconductor while preserving transistor on/off current ratio > $10^6$. The maximum current is ultimately limited by self-heating and could exceed 1 mA/um with better device heat sinking. With their 0.1 nA/um off-current, such doped MoS${}_2$ devices approach several low-power transistor metrics required by the international technology roadmap

To appear in ACS Nano (2021)