Hopping transport in TiO2:Co: A signature of multiphase behavior

Kennedy, R. J.; Stampe, P. A.; Erhong Hu, P. A.; Peng Xiong; von Molnár, Stephan; Yan Xin
April 2004
Applied Physics Letters;4/12/2004, Vol. 84 Issue 15, p2832
Academic Journal
TiO2:Co films have been grown in the rutile phase under varying oxygen growth pressures. Detailed microstructural analysis using transmission electron microscopy shows that reduced growth pressure increases the presence of cobalt clusters. The resistivity is found to follow a log(ρ)∼T-1/2 dependence over a wide temperature range. This behavior is characteristic of hopping transport in multiphase systems and implies the presence of cobalt clustering. Thus, transport measurements are shown to be sensitive to the appearance of metallic clusters in these systems and suggest a rapid method for determing the presence of clustering in these and other magnetically doped semiconductor systems. © 2004 American Institute of Physics.


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