Growth of centimeter-scale atomically thin MoS2 films by pulsed laser deposition
We are reporting the growth of single layer and few-layer MoS2 films on single crystal sapphire substrates using a pulsed-laser deposition technique. A pulsed KrF excimer laser (wavelength: 248 nm; pulse width: 25 ns) was used to ablate a polycrystalline MoS2 target. The material thus ablated was de...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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AIP Publishing LLC
2015-05-01
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| Series: | APL Materials |
| Online Access: | http://dx.doi.org/10.1063/1.4921580 |
| _version_ | 1818035239398670336 |
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| author | Gene Siegel Y. P. Venkata Subbaiah Megan C. Prestgard Ashutosh Tiwari |
| author_facet | Gene Siegel Y. P. Venkata Subbaiah Megan C. Prestgard Ashutosh Tiwari |
| author_sort | Gene Siegel |
| collection | DOAJ |
| description | We are reporting the growth of single layer and few-layer MoS2 films on single crystal sapphire substrates using a pulsed-laser deposition technique. A pulsed KrF excimer laser (wavelength: 248 nm; pulse width: 25 ns) was used to ablate a polycrystalline MoS2 target. The material thus ablated was deposited on a single crystal sapphire (0001) substrate kept at 700 °C in an ambient vacuum of 10−6 Torr. Detailed characterization of the films was performed using atomic force microscopy (AFM), Raman spectroscopy, UV-Vis spectroscopy, and photoluminescence (PL) measurements. The ablation of the MoS2 target by 50 laser pulses (energy density: 1.5 J/cm2) was found to result in the formation of a monolayer of MoS2 as shown by AFM results. In the Raman spectrum, A1g and E12g peaks were observed at 404.6 cm−1 and 384.5 cm−1 with a spacing of 20.1 cm−1, confirming the monolayer thickness of the film. The UV-Vis absorption spectrum exhibited two exciton absorption bands at 672 nm (1.85 eV) and 615 nm (2.02 eV), with an energy split of 0.17 eV, which is in excellent agreement with the theoretically predicted value of 0.15 eV. The monolayer MoS2 exhibited a PL peak at 1.85 eV confirming the direct nature of the band-gap. By varying the number of laser pulses, bi-layer, tri-layer, and few-layer MoS2 films were prepared. It was found that as the number of monolayers (n) in the MoS2 films increases, the spacing between the A1g and E12g Raman peaks (Δf) increases following an empirical relation,
Δ
f
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.
45
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.
42
1
+
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.
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0
.
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. |
| first_indexed | 2024-12-10T06:51:54Z |
| format | Article |
| id | doaj.art-aa9ad609dc6e4f7a8ed43d46a5493689 |
| institution | Directory Open Access Journal |
| issn | 2166-532X |
| language | English |
| last_indexed | 2024-12-10T06:51:54Z |
| publishDate | 2015-05-01 |
| publisher | AIP Publishing LLC |
| record_format | Article |
| series | APL Materials |
| spelling | doaj.art-aa9ad609dc6e4f7a8ed43d46a54936892022-12-22T01:58:32ZengAIP Publishing LLCAPL Materials2166-532X2015-05-0135056103056103-710.1063/1.4921580004505APMGrowth of centimeter-scale atomically thin MoS2 films by pulsed laser depositionGene Siegel0Y. P. Venkata Subbaiah1Megan C. Prestgard2Ashutosh Tiwari3Nanostructured Materials Research Laboratory, Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, USANanostructured Materials Research Laboratory, Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, USANanostructured Materials Research Laboratory, Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, USANanostructured Materials Research Laboratory, Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, USAWe are reporting the growth of single layer and few-layer MoS2 films on single crystal sapphire substrates using a pulsed-laser deposition technique. A pulsed KrF excimer laser (wavelength: 248 nm; pulse width: 25 ns) was used to ablate a polycrystalline MoS2 target. The material thus ablated was deposited on a single crystal sapphire (0001) substrate kept at 700 °C in an ambient vacuum of 10−6 Torr. Detailed characterization of the films was performed using atomic force microscopy (AFM), Raman spectroscopy, UV-Vis spectroscopy, and photoluminescence (PL) measurements. The ablation of the MoS2 target by 50 laser pulses (energy density: 1.5 J/cm2) was found to result in the formation of a monolayer of MoS2 as shown by AFM results. In the Raman spectrum, A1g and E12g peaks were observed at 404.6 cm−1 and 384.5 cm−1 with a spacing of 20.1 cm−1, confirming the monolayer thickness of the film. The UV-Vis absorption spectrum exhibited two exciton absorption bands at 672 nm (1.85 eV) and 615 nm (2.02 eV), with an energy split of 0.17 eV, which is in excellent agreement with the theoretically predicted value of 0.15 eV. The monolayer MoS2 exhibited a PL peak at 1.85 eV confirming the direct nature of the band-gap. By varying the number of laser pulses, bi-layer, tri-layer, and few-layer MoS2 films were prepared. It was found that as the number of monolayers (n) in the MoS2 films increases, the spacing between the A1g and E12g Raman peaks (Δf) increases following an empirical relation, Δ f = 26 . 45 − 15 . 42 1 + 1 . 44 n 0 . 9 cm − 1 .http://dx.doi.org/10.1063/1.4921580 |
| spellingShingle | Gene Siegel Y. P. Venkata Subbaiah Megan C. Prestgard Ashutosh Tiwari Growth of centimeter-scale atomically thin MoS2 films by pulsed laser deposition APL Materials |
| title | Growth of centimeter-scale atomically thin MoS2 films by pulsed laser deposition |
| title_full | Growth of centimeter-scale atomically thin MoS2 films by pulsed laser deposition |
| title_fullStr | Growth of centimeter-scale atomically thin MoS2 films by pulsed laser deposition |
| title_full_unstemmed | Growth of centimeter-scale atomically thin MoS2 films by pulsed laser deposition |
| title_short | Growth of centimeter-scale atomically thin MoS2 films by pulsed laser deposition |
| title_sort | growth of centimeter scale atomically thin mos2 films by pulsed laser deposition |
| url | http://dx.doi.org/10.1063/1.4921580 |
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