Nature Materials
Nature Materials
5 years ago

Direct observation of a two-dimensional hole gas at oxide interfaces

Direct observation of a two-dimensional hole gas at oxide interfaces
S. H. Oh, T. R. Paudel, E. Y. Tsymbal, M. S. Rzchowski, J. Seo, L. J. Brillson, J. W. Lee, N. Campbell, T. J. Asel, J. Lee, C. B. Eom, H. Zhou, B. Noesges, H. Lee, B. Park
The discovery of a two-dimensional electron gas (2DEG) at the LaAlO3/SrTiO3 interface1 has resulted in the observation of many properties2,3,4,5 not present in conventional semiconductor heterostructures, and so become a focal point for device applications6,7,8. Its counterpart, the two-dimensional hole gas (2DHG), is expected to complement the 2DEG. However, although the 2DEG has been widely observed9, the 2DHG has proved elusive. Herein we demonstrate a highly mobile 2DHG in epitaxially grown SrTiO3/LaAlO3/SrTiO3 heterostructures. Using electrical transport measurements and in-line electron holography, we provide direct evidence of a 2DHG that coexists with a 2DEG at complementary heterointerfaces in the same structure. First-principles calculations, coherent Bragg rod analysis and depth-resolved cathodoluminescence spectroscopy consistently support our finding that to eliminate ionic point defects is key to realizing a 2DHG. The coexistence of a 2DEG and a 2DHG in a single oxide heterostructure provides a platform for the exciting physics of confined electron–hole systems and for developing applications.

Publisher URL: https://www.nature.com/articles/s41563-017-0002-4

DOI: 10.1038/s41563-017-0002-4

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