Jullien M. , Horwat D. , Manzeh F. , Escobar Galindo R. , Bauer P. , Pierson J.F. , ENDRINO ARMENTEROS, JOSÉ LUIS
Si
Sol. Energy Mater. Sol. Cells
Article
Científica
4.542
2.182
01/01/2011
000292945700049
2-s2.0-79958115638
Transparent Al-doped ZnO thin films were deposited by reactive magnetron sputtering with different oxygen flow rates. The electronic resistivity, measured by the 4 point-probe method, is very sensitive to the sample position relative to the magnetron axis: the closer the magnetron from the axis the higher the resistivity. This is more pronounced for the films deposited under higher oxygen flow rate. Neither Rutherford backscattering spectroscopy nor ZnK edge X-ray absorption near-edge structure (XANES) analyses evidenced any change in chemical composition such as a measurable variation of the oxygen stoichiometry. XANES at the AlK and OK edges show that (i) a portion of the aluminum atoms get positioned in octahedral conformation with oxygen, consistent with the formation of an Al2O3(ZnO)m nanolaminate structure, (ii) the films exhibit relaxed O-terminated (0 0 0 1) surfaces with a higher density of empty states in more resistive samples. These two findings are believed to play a significant role on the electrical measurements by dopant deactivation and by creating an insulating barrier at the film surface, respectively. © 2011 Elsevier B.V.
Al-doped ZnO; Aluminum atoms; Chemical compositions; Dopant deactivation; Electrical measurement; EmptyState; Film surfaces; Homologous phase; Insulating barriers; Nano scale; Nanolaminate structures; Octahedral conformations; Oxygen flow rates; Oxygen stoichiometry; Reactive magnetron sputtering; Sample position; Structural feature; Transparent conducting oxide; X-ray absorption near-edge structure; XANES; ZnO; Absorption; Absorption spectroscopy; Chemical analysis; Density functional theory; Doping (additives); Electronic properties; Electronic structure; Flow rate; Metallic films; Optical films; Oxygen; Rutherford backscattering spectroscopy; Stoichiometry; Thin films; X ray absorption; Zinc oxide; Aluminum