Dopant ion size and electronic structure effects on transparent conducting oxides. Sc-doped CdO thin films grown by MOCVD

被引:119
作者
Jin, S
Yang, Y
Medvedeva, JE
Ireland, JR
Metz, AW
Ni, J
Kannewurf, CR
Freeman, AJ [1 ]
Marks, TJ
机构
[1] Northwestern Univ, Mat Res Ctr, Evanston, IL 60208 USA
[2] Northwestern Univ, Dept Chem, Evanston, IL 60208 USA
[3] Northwestern Univ, Dept Phys & Astron, Evanston, IL 60208 USA
[4] Northwestern Univ, Dept Elect & Comp Engn, Evanston, IL 60208 USA
关键词
D O I
10.1021/ja0467925
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
A series of Sc-doped CdO (CSO) thin films have been grown on both amorphous glass and single-crystal MgO(100) substrates at 400 degreesC by MOCVD. Both the experimental data and theoretical calculations indicate that Sc3+ doping shrinks the CdO lattice parameters due to its relatively small six-coordinate ionic radius, 0.89 Angstrom, vs 1.09 Angstrom for Cd2+. Conductivities as high as 18100 S/cm are achieved for CSO films grown on MgO(100) at a Sc doping level of 1.8 atom %. The CSO thin films exhibit an average transmittance >80% in the visible range. Sc3+ doping widens the optical band gap from 2.7 to 3.4 eV via a Burstein-Moss energy level shift, in agreement with the results of band structure calculations within the sX-LDA (screened-exchange local density approximation) formalism. Epitaxial CSO films on single-crystal MgO(1 00) exhibit significantly higher mobilities (up to 217 cm(2)/(V(.)s)) and carrier concentrations than films on glass, arguing that the epitaxial CSO films possess fewer scattering centers and higher doping efficiencies due to the highly textured microstructure. Finally, the band structure calculations provide a microscopic explanation for the observed dopant size effects on the structural, electronic, and optical properties of CSO.
引用
收藏
页码:13787 / 13793
页数:7
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