Direct n- to p-Type Channel Conversion in Monolayer/Few-Layer WS<sub>2</sub> Field-Effect Transistors by Atomic Nitrogen Treatment.
basic_science · Level V
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- Record sourced from PubMed, PMID 29505235.
- Also identified by DOI 10.1021/acsnano.7b08261.
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Abstract
We present a method for substitutional p-type doping in monolayer (1L) and few-layer (FL) WS<sub>2</sub> using highly reactive nitrogen atoms. We demonstrate that the nitrogen-induced lattice distortion in atomically thin WS<sub>2</sub> is negligible due to its low kinetic energy. The electrical characteristics of 1L/FL WS<sub>2</sub> field-effect transistors (FETs) clearly show an n-channel to p-channel conversion with nitrogen incorporation. We investigate the defect formation energy and the origin of p-type conduction using first-principles calculations. We reveal that a defect state appears near the Fermi level, leading to a shallow acceptor level at 0.24 eV above the valence band maximum in nitrogen-doped 1L/FL WS<sub>2</sub>. This doping strategy enables a substitutional p-type doping in intrinsically n-type 1L/FL transition metal dichalcogenides (TMDCs) with tunable control of dopants, offering a method for realizing complementary metal-oxide-semiconductor FETs and optoelectronic devices on 1L/FL TMDCs by overcoming one of the major limits of TMDCs, that is, their n-type unipolar conduction.