High-mobility semiconducting ultrathin films form the basis of modern electronics, and may lead to the scalable fabrication of highly performing devices. Because the ultrathin limit cannot be reached for traditional semiconductors, identifying new two-dimensional materials with both high carrier mobility and a large electronic bandgap is a pivotal goal of fundamental research1,2,3,4,5,6,7,8,9. However, air-stable ultrathin semiconducting materials with superior performances remain elusive at present10. Here, we report ultrathin films of non-encapsulated layered Bi2O2Se, grown by chemical vapour deposition, which demonstrate excellent air stability and high-mobility semiconducting behaviour. We observe bandgap values of ∼0.8 eV, which are strongly dependent on the film thickness due to quantum-confinement effects. An ultrahigh Hall mobility value of >20,000 cm2 V−1 s−1 is measured in as-grown Bi2O2Se nanoflakes at low temperatures. This value is comparable to what is observed in graphene grown by chemical vapour deposition11 and at the LaAlO3–SrTiO3 interface12, making the detection of Shubnikov–de Haas quantum oscillations possible. Top-gated field-effect transistors based on Bi2O2Se crystals down to the bilayer limit exhibit high Hall mobility values (up to 450 cm2 V−1 s−1), large current on/off ratios (>106) and near-ideal subthreshold swing values (∼65 mV dec–1) at room temperature. Our results make Bi2O2Se a promising candidate for future high-speed and low-power electronic applications.
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The authors thank X. B. Ren and C. H. Jin for analysis of elemental maps. H.L.P. acknowledges support from the National Basic Research Program of China (grant numbers 2014CB932500 and 2016YFA0200101), the National Natural Science Foundation of China (grant number 21525310) and the National Program for Support of Top-Notch Young Professionals. H.T.Y., Y.C. and H.Y.H. were supported by the Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under contract number DE-AC02-76SF00515.
The authors declare no competing financial interests.
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Wu, J., Yuan, H., Meng, M. et al. High electron mobility and quantum oscillations in non-encapsulated ultrathin semiconducting Bi2O2Se. Nature Nanotech 12, 530–534 (2017). https://doi.org/10.1038/nnano.2017.43
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