Microstructural evolution and electrical property of Ta-doped SnO films

Ta-doped tin oxide, SnO , films have been deposited using metalorganic chemical vapor deposition system on sapphire (0001) 2 substrates in temperature range of 400–6008C. When Ta concentration is varied from 0 to 8.30 at.% in the films, the electrical resistivity is changed by three orders of magnitude where the minimum resistivity was observed at 1.35% of Ta. An increase in the carrier concentration is a dominant factor responsible for such a large decrease in the resistivity while improved crystalinity contributes to the improvement in the mobility among doped samples. Microstructural investigation revealed the Ta-doped film showed a clean epitaxial relationship of SnO (100)y yAl O (0001) with SnO w100xy yAl O N1210M between the substrate and the 2 2 3 2 2 3 ̄ film while undoped film had a weak epitaxial correlation with an extra epitaxial relationship of SnO (100)y yAl O (0001) with 2 2 3 SnO w010xy yAl O N1100M. 2002 Elsevier Science B.V. All rights reserved. 2 2 3 ̄