Pulikkotil, J. J. (2019) Coexistence of quasi-two dimensional electron and hole gas in a single tier Ca0.5TaO3/SrTiO3 oxide heterostructure. APL Materials , 7 (7). 071108-071115. ISSN 2166-532X
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Abstract
Quasi-two-dimensional electron gas has been realized at the polar-nonpolar interface of several insulating oxide heterostructures. However, its hole counterpart remains elusive. In an attempt to find a novel system that exhibits quasi-two-dimensional hole gas (q-2DHG) at the heterointerface, we adopt to materials search, first based on phenomenology followed by a comprehensive set of calculations based on first-principles density functional theory. Our studies show the epitaxial growth of cubic Ca0.5TaO3 on TiO2 terminated substrate display (q-2DHG). The hole gas emanates from the O 2p orbitals of the TiO2 layers of the substrate. On the other hand, an electron gas is formed at the (001) TaO2 top surface, thereby representing the heterostructure as a coupled quantum well system. The partial filling of the Ta 5dt(2g) conduction band indicates electron reconstruction, in agreement with the polar catastrophe model. Besides, a critical thickness of three monolayers is deduced from the calculations for the formation of q-2DHG in the Ca0.5TaO3/SrTiO3 heterostructure, which is consistent with the model prediction based on the modern theory of polarization. With both cubic systems, Ca0.5TaO3 and SrTiO3, having a similar underlying symmetry and minimal lattice mismatch, epitaxial growth with an abrupt interface can be well anticipated. Such a single-tier oxide heterostructure composed of separated confined hole-electron subsystems is expected to provide a platform to unravel exciting physics and also for functional devices related to oxide electronics.
| Item Type: | Article |
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| Additional Information: | Copyright for this article belongs to M/s Elsevier. |
| Subjects: | Materials Science Applied Physics/Condensed Matter Nanoscience/ Nanotechnology |
| Divisions: | UNSPECIFIED |
| Depositing User: | Mr. Yogesh Joshi |
| Date Deposited: | 31 Jan 2020 08:44 |
| Last Modified: | 31 Jan 2020 08:44 |
| URI: | http://npl.csircentral.net/id/eprint/4124 |
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