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Optical investigation of the natural electron doping in thin MoS2 films deposited on dielectric substrates.

Sercombe D, Schwarz S, Del Pozo-Zamudio O, Liu F, Robinson BJ, Chekhovich EA, Tartakovskii II, Kolosov O, Tartakovskii AI - Sci Rep (2013)

Bottom Line: However, large surface-to-volume ratio in thin films enhances the significance of surface interactions and charging effects requiring new understanding.PL spectra for MoS2 films deposited on SiO2 substrates are found to vary widely.Observed great sensitivity of optical characteristics of 2D films to surface interactions has important implications for optoelectronics applications of layered materials.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom.

ABSTRACT
Two-dimensional (2D) compounds provide unique building blocks for novel layered devices and hybrid photonic structures. However, large surface-to-volume ratio in thin films enhances the significance of surface interactions and charging effects requiring new understanding. Here we use micro-photoluminescence (PL) and ultrasonic force microscopy to explore the influence of the dielectric environment on optical properties of a few monolayer MoS2 films. PL spectra for MoS2 films deposited on SiO2 substrates are found to vary widely. This film-to-film variation is suppressed by additional capping of MoS2 with SiO2 and Si(x)N(y), improving mechanical coupling of MoS2 with surrounding dielectrics. We show that the observed PL non-uniformities are related to strong variation in the local electron charging of MoS2 films. In completely encapsulated films, negative charging is enhanced leading to uniform optical properties. Observed great sensitivity of optical characteristics of 2D films to surface interactions has important implications for optoelectronics applications of layered materials.

No MeSH data available.


PL FWHM of exciton complex A in thin MoS2 films.Data for MoS2 films deposited on thermally and PECVD grown SiO2 substrates is shown with blue and red, respectively. (a) PL FWHM of uncapped MoS2 films. (b) PL FWHM of SixNy capped MoS2 films. (c) PL FWHM of SiO2 capped MoS2 films.
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f4: PL FWHM of exciton complex A in thin MoS2 films.Data for MoS2 films deposited on thermally and PECVD grown SiO2 substrates is shown with blue and red, respectively. (a) PL FWHM of uncapped MoS2 films. (b) PL FWHM of SixNy capped MoS2 films. (c) PL FWHM of SiO2 capped MoS2 films.

Mentions: In this section we will present the lineshape analysis for the A exciton PL based on the measurement of full width at half maximum (FWHM) in each PL spectrum. This approach allows one to account for contributions of the three PL features, L, A0 and A−. The data are summarized in Fig. 4 and Table 1.


Optical investigation of the natural electron doping in thin MoS2 films deposited on dielectric substrates.

Sercombe D, Schwarz S, Del Pozo-Zamudio O, Liu F, Robinson BJ, Chekhovich EA, Tartakovskii II, Kolosov O, Tartakovskii AI - Sci Rep (2013)

PL FWHM of exciton complex A in thin MoS2 films.Data for MoS2 films deposited on thermally and PECVD grown SiO2 substrates is shown with blue and red, respectively. (a) PL FWHM of uncapped MoS2 films. (b) PL FWHM of SixNy capped MoS2 films. (c) PL FWHM of SiO2 capped MoS2 films.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3860010&req=5

f4: PL FWHM of exciton complex A in thin MoS2 films.Data for MoS2 films deposited on thermally and PECVD grown SiO2 substrates is shown with blue and red, respectively. (a) PL FWHM of uncapped MoS2 films. (b) PL FWHM of SixNy capped MoS2 films. (c) PL FWHM of SiO2 capped MoS2 films.
Mentions: In this section we will present the lineshape analysis for the A exciton PL based on the measurement of full width at half maximum (FWHM) in each PL spectrum. This approach allows one to account for contributions of the three PL features, L, A0 and A−. The data are summarized in Fig. 4 and Table 1.

Bottom Line: However, large surface-to-volume ratio in thin films enhances the significance of surface interactions and charging effects requiring new understanding.PL spectra for MoS2 films deposited on SiO2 substrates are found to vary widely.Observed great sensitivity of optical characteristics of 2D films to surface interactions has important implications for optoelectronics applications of layered materials.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom.

ABSTRACT
Two-dimensional (2D) compounds provide unique building blocks for novel layered devices and hybrid photonic structures. However, large surface-to-volume ratio in thin films enhances the significance of surface interactions and charging effects requiring new understanding. Here we use micro-photoluminescence (PL) and ultrasonic force microscopy to explore the influence of the dielectric environment on optical properties of a few monolayer MoS2 films. PL spectra for MoS2 films deposited on SiO2 substrates are found to vary widely. This film-to-film variation is suppressed by additional capping of MoS2 with SiO2 and Si(x)N(y), improving mechanical coupling of MoS2 with surrounding dielectrics. We show that the observed PL non-uniformities are related to strong variation in the local electron charging of MoS2 films. In completely encapsulated films, negative charging is enhanced leading to uniform optical properties. Observed great sensitivity of optical characteristics of 2D films to surface interactions has important implications for optoelectronics applications of layered materials.

No MeSH data available.