Defects activated photoluminescence in two-dimensional semiconductors: interplay between bound, charged and free excitons
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Open Access
- 13 September 2013
- journal article
- Published by Springer Science and Business Media LLC in Scientific Reports
- Vol. 3 (1), 2657
- https://doi.org/10.1038/srep02657
Abstract
Point defects in semiconductors can trap free charge carriers and localize excitons. The interaction between these defects and charge carriers becomes stronger at reduced dimensionalities and is expected to greatly influence physical properties of the hosting material. We investigated effects of anion vacancies in monolayer transition metal dichalcogenides as two-dimensional (2D) semiconductors where the vacancies density is controlled by α-particle irradiation or thermal-annealing. We found a new, sub-bandgap emission peak as well as increase in overall photoluminescence intensity as a result of the vacancy generation. Interestingly, these effects are absent when measured in vacuum. We conclude that in opposite to conventional wisdom, optical quality at room temperature cannot be used as criteria to assess crystal quality of the 2D semiconductors. Our results not only shed light on defect and exciton physics of 2D semiconductors, but also offer a new route toward tailoring optical properties of 2D semiconductors by defect engineering.Keywords
This publication has 24 references indexed in Scilit:
- Anomalous Raman spectra and thickness-dependent electronic properties of WSePhysical Review B, 2013
- Phonon softening and direct to indirect band gap crossover in strained single-layer MoSePhysical Review B, 2013
- Electrical control of neutral and charged excitons in a monolayer semiconductorNature Communications, 2013
- Electrical control of optical properties of monolayer MoS2Solid State Communications, 2013
- Tightly bound trions in monolayer MoS2Nature Materials, 2012
- Thermally Driven Crossover from Indirect toward Direct Bandgap in 2D Semiconductors: MoSe2 versus MoS2Nano Letters, 2012
- Visibility of dichalcogenide nanolayersNanotechnology, 2011
- Atomically Thin: A New Direct-Gap SemiconductorPhysical Review Letters, 2010
- Anomalous Lattice Vibrations of Single- and Few-Layer MoS2ACS Nano, 2010
- Analytic solution of a two-dimensional hydrogen atom. I. Nonrelativistic theoryPhysical Review A, 1991