Precise calibration of Mg concentration in Mg_xZn_(1−x)O thin films grown on ZnO substrates
Abstract
The growth techniques for Mg_xZn_(1−x)O thin films have advanced at a rapid pace in recent years, enabling the application of this material to a wide range of optical and electrical applications. In designing structures and optimizing device performances, it is crucial that the Mg content of the alloy be controllable and precisely determined. In this study, we have established laboratory-based methods to determine the Mg content of Mg_xZn_(1−x)O thin films grown on ZnO substrates, ranging from the solubility limit of x ∼ 0.4 to the dilute limit of x < 0.01. For the absolute determination of Mg content, Rutherford backscattering spectroscopy is used for the high Mg region above x = 0.14, while secondary ion mass spectroscopy is employed to quantify low Mg content. As a lab-based method to determine the Mg content, c-axis length is measured by x-ray diffraction and is well associated with Mg content. The interpolation enables the determination of Mg content to x = 0.023, where the peak from the ZnO substrate overlaps the Mg_xZn_(1−x)O peak in standard laboratory equipment, and thus limits quantitative determination. At dilute Mg contents below x = 0.023, the localized exciton peak energy of the Mg_xZn_(1−x)O films as measured by photoluminescence is found to show a linear Mg content dependence, which is well resolved from the free exciton peak of ZnO substrate down to x = 0.0043. Our results demonstrate that x-ray diffraction and photoluminescence in combination are appropriate methods to determine Mg content in a wide Mg range from x = 0.004 to 0.40 in a laboratory environment.
Additional Information
© 2012 American Institute of Physics. (Received 10 July 2012; accepted 25 July 2012; published online 29 August 2012) This work was partly supported by "Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST)" Program from the Japan Society for the Promotion of Science (JSPS) initiated by the Council for Science and Technology Policy.Attached Files
Published - 1.4748306.pdf
Accepted Version - 1208.2074.pdf
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Additional details
- Eprint ID
- 102319
- Resolver ID
- CaltechAUTHORS:20200403-115231081
- Japan Society for the Promotion of Science (JSPS)
- Council for Science and Technology Policy (CSTP)
- Created
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2020-04-03Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field