Materials 2012, 5(11), 2088-2100; doi:10.3390/ma5112088
Electronic and Optical Properties of Substitutional and Interstitial Si-Doped ZnO
1
Department of Materials Engineering, Ming Chi University of Technology, New Taipei 24301, Taiwan
2
Center for Thin Film Technologies and Applications, Ming Chi University of Technology, New Taipei 24301, Taiwan
*
Author to whom correspondence should be addressed.
Received: 9 August 2012 / Revised: 15 October 2012 / Accepted: 23 October 2012 / Published: 29 October 2012
(This article belongs to the Special Issue Compound Semiconductor Materials)
Abstract
This study investigates the formation energies, electronic structures, and optical properties of pure and Si-doped ZnO using density functional theory and the Hubbard U (DFT + Ud + Up) method. The difference in lattice constants between calculated results and experimental measurements is within 1%, and the calculated band gap of pure ZnO is in excellent agreement with experimental values. This study considers three possible Si-doped ZnO structures including the substitution of Si for Zn (Sis(Zn)), interstitial Si in an octahedron (Sii(oct)), and interstitial Si in a tetrahedron (Sii(tet)). Results show that the formation energy of Sis(Zn) defects is the lowest, indicating that Sis(Zn) defects are formed more easily than Sii(oct) and Sii(tet). All three of the Si defect models exhibited n-type conductive characteristics, and except for the Sii(oct) mode the optical band gap expanded beyond that of pure ZnO. In both the Sii(oct) and Sii(tet) models, a heavier effective mass decreased carrier mobility, and deeper donor states significantly decreased transmittance. Therefore, the existence of interestitial Si atoms was bad for the electric and optical properties of ZnO.Keywords:
First-principles; DFT + U; Si-doped ZnO; electronic structure; optical property
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).
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MDPI and ACS Style
Wu, H.-C.; Peng, Y.-C.; Shen, T.-P. Electronic and Optical Properties of Substitutional and Interstitial Si-Doped ZnO. Materials 2012, 5, 2088-2100.
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