Electronic States in Zinc Magnesium Oxide Alloy Semiconductors: Hard X-ray Photoemission Spectroscopy and Density Functional Theory Calculations
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- 作者：Takeo Ohsawa ; Yutaka Adachi ; Isao Sakaguchi ; Kenji Matsumoto ; Hajime Haneda ; Shigenori Ueda ; Hideki Yoshikawa ; Keisuke Kobayashi ; Naoki Ohashi
- 刊名：Chemistry of Materials
- 出版年：2009
- 出版时间：January 13, 2009
- 年：2009
- 卷：21
- 期：1
- 页码：144-150
- 全文大小：291K
- 年卷期：v.21,no.1(January 13, 2009)
- ISSN：1520-5002
文摘
The electronic states of zinc magnesium oxide (Zn1−xMgx)O thin films were determined exactly by hard X-ray photoemission spectroscopy (HX-PES) using synchrotron radiation. The Zn 2p core level was shifted to a higher binding energy along with widening of the bandgap by alloying with MgO, whereas the shift of the O 1s peak was less than that of the Zn 2p peak. Density functional theory (DFT) calculations revealed that the electronic state of an O ion bonding with an adjacent Mg ion is remarkably different from that not bonding with a Mg ion. As a result, the energy shift observed in the O 1s peak results from a combination of the expansion of the bandgap energy and the chemical shift due to a change in the ionicity. The Fermi level is always situated just below the conduction band; this suggests that a shallow donor can be added, even in the alloy film with very high MgO fraction, for example, x = 0.47.