Molecular beam epitaxy of large-area SnSe 2 with monolayer thickness fluctuation
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2D Materials, ISSN: 2053-1583, Vol: 4, Issue: 1
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- Chemistry; Materials Science; Physics and Astronomy; Engineering; molecular beam epitaxy; van der Waals epitaxy; SnSe2; Raman spectroscopy; transmission electron microscopy; field effect transistor
The interest in layered materials is largely based on the expectation that they will be beneficial for a variety of applications, from low-power-consuming, wearable electronics to energy harvesting. However, the properties of layered materials are highly dependent on thickness, and the difficulty of controlling thickness over a large area has been a bottleneck for commercial applications. Here, we report layer-by-layer growth of SnSe, a layered semiconducting material, via van der Waals epitaxy. The films were fabricated on insulating mica substrates with substrate temperatures in the range of 210°C-370°C. The surface consists of a mixture of N and (N ± 1) layers, showing that the thickness of the film can be defined with monolayer accuracy (±0.6 nm). High-resolution transmission electron microscopy reveals a polycrystalline film with a grain size of ∼100 nm and clear Moiré patterns from overlapped grains with similar thickness. We also report field effect mobility values of 3.7 cmVsand 6.7 cmVsfor 11 and 22 nm thick SnSe, respectively. SnSefilms with customizable thickness can provide valuable platforms for industry and academic researchers to fully exploit the potential of layered materials.