Metatungstate Chemical Vapor Deposition of WSe<sub>2</sub>: Substrate Effects, Shapes, and Morphologies
Owing to their exceptional properties, which are usually determined by the growth conditions, 2D transition metal dichalcogenides (TMDCs) offer numerous research directions for applications in the fields of spintronics, valleytronics, and optoelectronics. Here, we focus on the chemical vapor deposit...
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MDPI AG
2024-02-01
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| Online Access: | https://www.mdpi.com/2073-4352/14/2/184 |
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| author | Krastyo Buchkov Peter Rafailov Nikolay Minev Vladimira Videva Velichka Strijkova Todor Lukanov Dimitre Dimitrov Vera Marinova |
| author_facet | Krastyo Buchkov Peter Rafailov Nikolay Minev Vladimira Videva Velichka Strijkova Todor Lukanov Dimitre Dimitrov Vera Marinova |
| author_sort | Krastyo Buchkov |
| collection | DOAJ |
| description | Owing to their exceptional properties, which are usually determined by the growth conditions, 2D transition metal dichalcogenides (TMDCs) offer numerous research directions for applications in the fields of spintronics, valleytronics, and optoelectronics. Here, we focus on the chemical vapor deposition (CVD) synthesis of WSe<sub>2</sub> (tungsten diselenide) nanoclusters/nanoflakes by using a liquid precursor for tungsten (ammonium metatungstate) on Si/SiO<sub>2</sub>, fused silica, and sapphire substrates. Various WSe<sub>2</sub> clusters with different sizes, thicknesses, and geometries were analyzed by means of optical and atomic force microscopy (AFM) and Raman spectroscopy. The observed structures were mostly WSe<sub>2</sub> multilayers; however, monolayer formations were also found. They showed significant morphological differences, as well as wide nucleation density and size variations, possibly related to precursor/substrate surface interactions under the same CVD synthesis conditions. The largest WSe<sub>2</sub> domains with a lateral size of up to hundreds of micrometers were observed on sapphire, probably caused by a higher growth rate of singular nucleation sites. WSe<sub>2</sub> domains with irregular and triangular shapes were simultaneously identified on fused silica, whereas multilayered pyramidal WSe<sub>2</sub> structures dominated in the case of Si/SiO<sub>2</sub> substrates. The application of polarized Raman spectroscopy to precisely determine and differentiate the characteristic vibrational modes (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi mathvariant="normal">A</mi></mrow><mrow><mn>1</mn><mi mathvariant="normal">g</mi></mrow></msub></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi mathvariant="normal">E</mi></mrow><mrow><mn>2</mn><mi mathvariant="normal">g</mi></mrow></msub></mrow></semantics></math></inline-formula>, and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2</mn><mi mathvariant="normal">L</mi><mi mathvariant="normal">A</mi><mo>(</mo><mi mathvariant="normal">M</mi><mo>)</mo></mrow></semantics></math></inline-formula>) enabled the unambiguous identification of 2D and/or multilayered WSe<sub>2</sub> formations with a high crystallinity level. The presented comparative analysis of samples prepared in relatively simple synthesis conditions (moderate working temperatures and ambient pressure) provides a base for further progress of the facile metatungstate CVD method and relevant opportunities for the exploration of 2D TMDC materials. |
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| spelling | doaj.art-d177b8933b0946ac9149f7e863278fc22024-02-23T15:13:18ZengMDPI AGCrystals2073-43522024-02-0114218410.3390/cryst14020184Metatungstate Chemical Vapor Deposition of WSe<sub>2</sub>: Substrate Effects, Shapes, and MorphologiesKrastyo Buchkov0Peter Rafailov1Nikolay Minev2Vladimira Videva3Velichka Strijkova4Todor Lukanov5Dimitre Dimitrov6Vera Marinova7Institute of Solid State Physics, Bulgarian Academy of Sciences 72, Tzarigradsko Chaussee Blvd, 1784 Sofia, BulgariaInstitute of Solid State Physics, Bulgarian Academy of Sciences 72, Tzarigradsko Chaussee Blvd, 1784 Sofia, BulgariaInstitute of Optical Materials and Technologies, Bulgarian Academy of Sciences, Acad. G. Bontchev Str. 109, 1113 Sofia, BulgariaInstitute of Optical Materials and Technologies, Bulgarian Academy of Sciences, Acad. G. Bontchev Str. 109, 1113 Sofia, BulgariaInstitute of Optical Materials and Technologies, Bulgarian Academy of Sciences, Acad. G. Bontchev Str. 109, 1113 Sofia, BulgariaInstitute of Optical Materials and Technologies, Bulgarian Academy of Sciences, Acad. G. Bontchev Str. 109, 1113 Sofia, BulgariaInstitute of Solid State Physics, Bulgarian Academy of Sciences 72, Tzarigradsko Chaussee Blvd, 1784 Sofia, BulgariaInstitute of Optical Materials and Technologies, Bulgarian Academy of Sciences, Acad. G. Bontchev Str. 109, 1113 Sofia, BulgariaOwing to their exceptional properties, which are usually determined by the growth conditions, 2D transition metal dichalcogenides (TMDCs) offer numerous research directions for applications in the fields of spintronics, valleytronics, and optoelectronics. Here, we focus on the chemical vapor deposition (CVD) synthesis of WSe<sub>2</sub> (tungsten diselenide) nanoclusters/nanoflakes by using a liquid precursor for tungsten (ammonium metatungstate) on Si/SiO<sub>2</sub>, fused silica, and sapphire substrates. Various WSe<sub>2</sub> clusters with different sizes, thicknesses, and geometries were analyzed by means of optical and atomic force microscopy (AFM) and Raman spectroscopy. The observed structures were mostly WSe<sub>2</sub> multilayers; however, monolayer formations were also found. They showed significant morphological differences, as well as wide nucleation density and size variations, possibly related to precursor/substrate surface interactions under the same CVD synthesis conditions. The largest WSe<sub>2</sub> domains with a lateral size of up to hundreds of micrometers were observed on sapphire, probably caused by a higher growth rate of singular nucleation sites. WSe<sub>2</sub> domains with irregular and triangular shapes were simultaneously identified on fused silica, whereas multilayered pyramidal WSe<sub>2</sub> structures dominated in the case of Si/SiO<sub>2</sub> substrates. The application of polarized Raman spectroscopy to precisely determine and differentiate the characteristic vibrational modes (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi mathvariant="normal">A</mi></mrow><mrow><mn>1</mn><mi mathvariant="normal">g</mi></mrow></msub></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi mathvariant="normal">E</mi></mrow><mrow><mn>2</mn><mi mathvariant="normal">g</mi></mrow></msub></mrow></semantics></math></inline-formula>, and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>2</mn><mi mathvariant="normal">L</mi><mi mathvariant="normal">A</mi><mo>(</mo><mi mathvariant="normal">M</mi><mo>)</mo></mrow></semantics></math></inline-formula>) enabled the unambiguous identification of 2D and/or multilayered WSe<sub>2</sub> formations with a high crystallinity level. The presented comparative analysis of samples prepared in relatively simple synthesis conditions (moderate working temperatures and ambient pressure) provides a base for further progress of the facile metatungstate CVD method and relevant opportunities for the exploration of 2D TMDC materials.https://www.mdpi.com/2073-4352/14/2/184tungsten diselenidechemical vapor depositionRaman spectroscopyatomic force microscopy |
| spellingShingle | Krastyo Buchkov Peter Rafailov Nikolay Minev Vladimira Videva Velichka Strijkova Todor Lukanov Dimitre Dimitrov Vera Marinova Metatungstate Chemical Vapor Deposition of WSe<sub>2</sub>: Substrate Effects, Shapes, and Morphologies Crystals tungsten diselenide chemical vapor deposition Raman spectroscopy atomic force microscopy |
| title | Metatungstate Chemical Vapor Deposition of WSe<sub>2</sub>: Substrate Effects, Shapes, and Morphologies |
| title_full | Metatungstate Chemical Vapor Deposition of WSe<sub>2</sub>: Substrate Effects, Shapes, and Morphologies |
| title_fullStr | Metatungstate Chemical Vapor Deposition of WSe<sub>2</sub>: Substrate Effects, Shapes, and Morphologies |
| title_full_unstemmed | Metatungstate Chemical Vapor Deposition of WSe<sub>2</sub>: Substrate Effects, Shapes, and Morphologies |
| title_short | Metatungstate Chemical Vapor Deposition of WSe<sub>2</sub>: Substrate Effects, Shapes, and Morphologies |
| title_sort | metatungstate chemical vapor deposition of wse sub 2 sub substrate effects shapes and morphologies |
| topic | tungsten diselenide chemical vapor deposition Raman spectroscopy atomic force microscopy |
| url | https://www.mdpi.com/2073-4352/14/2/184 |
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