Photoluminescence Induced by Substitutional Nitrogen in Single-Layer Tungsten Disulfide.
basic_science · Level V
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- Record sourced from PubMed, PMID 35536919.
- Also identified by DOI 10.1021/acsnano.1c09809.
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Abstract
The electronic and optical properties of two-dimensional materials can be strongly influenced by defects, some of which can find significant implementations, such as controllable doping, prolonged valley lifetime, and single-photon emissions. In this work, we demonstrate that defects created by remote N<sub>2</sub> plasma exposure in single-layer WS<sub>2</sub> can induce a distinct low-energy photoluminescence (PL) peak at 1.59 eV, which is in sharp contrast to that caused by remote Ar plasma. This PL peak has a critical requirement on the N<sub>2</sub> plasma exposure dose, which is strongest for WS<sub>2</sub> with about 2.0% sulfur deficiencies (including substitutions and vacancies) and vanishes at 5.6% or higher sulfur deficiencies. Both experiments and first-principles calculations suggest that this 1.59 eV PL peak is caused by defects related to the sulfur substitutions by nitrogen, even though low-temperature PL measurements also reveal that not all the sulfur vacancies are remedied by the substitutional nitrogen. The distinct low-energy PL peak suggests that the substitutional nitrogen defect in single-layer WS<sub>2</sub> can potentially serve as an isolated artificial atom for creating single-photon emitters, and its intensity can also be used to monitor the doping concentrations of substitutional nitrogen.