Bipolar doping in van der Waals semiconductor through Flexo-doping

TL;DR

This paper introduces a physical, stress-based doping method for layered semiconductors like MoS2, enabling nanoscale patterning without chemical impurities, and demonstrates its effectiveness through experiments and theoretical analysis.

Contribution

It presents a novel strain-engineering technique for doping 2D semiconductors with high spatial resolution, avoiding traditional chemical doping limitations.

Findings

Achieved sub-100 nm doping patterns using localized stress.

Demonstrated strain-induced shifts in donor and acceptor energy levels.

Created functional devices like rectifiers and logic gates with stable operation.

Abstract

Doping plays a key role in functionalizing semiconductor devices, yet traditional chemical approaches relying on foreign-atom incorporation suffer from doping-asymmetry, pronounced lattice disorder and constrained spatial resolution. Here, we demonstrate a physical doping technique to directly write nanoscale doping patterns into layered semiconductors (MoS2). By applying localized tensile and compressive stress via an atomic force microscopy probe, p and n type conductance are simultaneously written into the designed area with sub-100-nm resolution, as verified by spatially resolved capacitance and photocurrent experiments. Density functional theory calculations reveal strain-driven shifts of donor and acceptor levels, as large as several hundreds of meV, linking mechanical stress to semiconductor doping. Fabricated strain-engineered junction efficiently rectifies the current flow and performs logic operations with stable dynamic response. This strain-driven approach enables spatially precise doping in van der Waals materials without degrading crystallinity, offering a versatile platform for nanoscale semiconductor devices.