Samples with oxide layers which were between 120 and 400nm in thickness were diffused with Ni, through the oxide, at temperatures of between 1420 and 1520K. The Ni distribution was determined by using a 4-probe resistivity technique. It was found that the distributions were anomalous in nature. The impurity was more heterogeneously distributed in the sub-surface region, and the concentration of electrically active Ni atoms increased with decreasing oxide layer thickness. The degree of heterogeneity of the impurity distribution in the sub-surface region, and the extent of this region, decreased upon increasing the thickness of the oxide layer.

F.M.Talipov, M.K.Bakhadyrkhanov, U.B.Soltamov: Izvestiya Akademii Nauk SSSR - Neorganicheskie Materialy, 1989, 25[6], 1037-8 (Inorganic Materials, 1989, 25[6], 872-3)