Controllable carrier concentration of two-dimensional TMDs by forming transition-metal suboxide layer for photoelectric devices

Two-dimensional (2D) transition-metal dichalcogenides (TMDs) have the potential to drive future innovation in the electronics industry. However, the controllability of charge concentration remains challenging due to the atomically thin channel, which perturbs the charge transport characteristics of nanodevices. Here, we demonstrate a strategy that uses the transition metal suboxide layer to modulate the photoelectrical characteristics of TMD channels. The carrier concentration in an n-type MoS2 channel is reduced from 2.05 × 1012 to 6.15 × 1010 cm−3, while it increases from 1.71 × 1010 to 2.76 × 1012 cm−3 for p-type WSe2 channels. Remarkably, the channel mobility remains unchanged or even slightly improves when the carrier concentration is appropriately tuned. Also, the homogenous channel is modulated into a photovoltaic homojunction with a tenfold enhancement of photoelectrical detectivity and response speed. The controllable strategy provides a simple design principle to realize high-performance 2D semiconductor-based optoelectronic and logic devices.