High Current Density in Monolayer MoS₂ Doped by AlO_<i>x</i>

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 °C) substoichiometric AlO_<i>x</i> provides a stable <i>n</i>-doping layer for monolayer MoS₂, compatible with circuit integration. This approach achieves carrier densities >2 × 10¹³ cm^-2, sheet resistance as low as ∼7 kΩ/□, and good contact resistance ∼480 Ω·μm in transistors from monolayer MoS₂ grown by chemical vapor deposition. We also reach record current density of nearly 700 μA/μm (>110 MA/cm²) along this three-atom-thick semiconductor while preserving transistor on/off current ratio >10⁶. The maximum current is ultimately limited by self-heating (SH) and could exceed 1 mA/μm with better device heat sinking. With their 0.1 nA/μm off-current, such doped MoS₂ devices approach several low-power transistor metrics required by the international technology roadmap.