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Aluminum - doped ZnO thin films (ZnO:Al) and Al - N co-doped (ZnOALN) thin films were prepared by RF diode sputtering from a ceramic target (ZnO+2 wt. % AI2O3) in Ar and Ar/25divide75 %N2 atmosphere. The ZnOAl films exhibited n-type conduction with a minimum resistivity (2times10-3 Omegacm), a high visible transmittance (> 82 %, including Corning glass substrate) and an optical band gap Eg ~ 3.3 eV. The p-type doping efficiency of the nitrogen was investigated as a function of the nitrogen content in the sputtering gas. The ZnO:Al:N thin films with p-type conduction were obtained for 75 % N2 in the Ar/N2 gas. Their resistivity and the hole concentration were 21 Omegacm and 7.8times1017 cm-3 respectively. The micro-Raman scattering measurements revealed N - related local vibrational modes (LVMs) at 276.44 cm-1 and 518.47 cm-1 in the spectra of the films grown with nitrogen and proved that the p-type conduction was a result of the nitrogen incorporation and formation of NO acceptors. The average transmittance (74divide86%, including Corning glass substrate) and Eg (3.22 - 3.10 eV) depended on the N2 content in the sputtering gas. The p-/n-type ZnO thin films were utilized for preparing p-n heterojunction structures on (100) n-type and (111) p-type silicon substrates. Rectification was clearly observed for both structures.
Date of Conference: 11-14 May 2008