Oxygen Vacancy Effects of Two-Dimensional Electron Gas in SrTiO3/KNbO3 Hetero Structure

Title
Oxygen Vacancy Effects of Two-Dimensional Electron Gas in SrTiO3/KNbO3 Hetero Structure
Authors
최우성강민규도영호정우석주병권윤석진유광수강종윤
Keywords
KNO; 2DEG; STO; Oxygen vacancy; Polar catastrophe
Issue Date
2013-08
Publisher
Journal of Sensor Science and Technology
Citation
VOL 22, NO 4, 244-248
Abstract
The discovery of a two-dimensional electron gas (2DEG) in LaAlO3 (LAO)/SrTiO3 (STO) heterostructure has stimulated intense research activity. We suggest a new structure model based on KNbO3 (KNO) material. The KNO thin films were grown on TiO2-terminated STO substrates as a p-type structure (NbO2/KO/TiO2) to form a two-dimensional hole gas (2DHG). The STO thin films were grown on KNO/TiO2-terminated STO substrates as an n-type structure to form a 2DEG. Oxygen pressure during the deposition of the KNO and STO thin films was changed so as to determine the effect of oxygen vacancies on 2DEGs. Our results showed conducting behavior in the n-type structure and insulating properties in the p-type structure. When both the KNO and STO thin films were deposited on a TiO2-terminated STO substrate at a low oxygen pressure, the conductivity was found to be higher than that at higher oxygen pressures. Furthermore, the heterostructure formed at various oxygen pressures resulted in structures with different current values. An STO/KNO heterostructure was also grown on the STO substrate, without using the buffered oxide etchant (BOE) treatment, so as to confirm the effects of the polar catastrophe mechanism. An STO/KNO heterostructure grown on an STO substrate without BOE treatment did not exhibit conductivity. Therefore, we expect that the mechanics of 2DEGs in the STO/KNO heterostructures are governed by the oxygen vacancy mechanism and the polar catastrophe mechanism.
URI
http://pubs.kist.re.kr/handle/201004/47956
ISSN
12255475
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KIST Publication > Article
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