Electrical and Structural Properties of Amorphous Metal—Metal-Oxide Systems

Abstract

Amorphous mixtures of Al-${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$, Sn-Sn${\mathrm{O}}_{2}$, Ta-${\mathrm{Ta}}_{2}$${\mathrm{O}}_{5}$, and Ni-NiO were sputtered in various concentrations at room temperature. The resistivity was measured as a function of temperature between 1 and 300 \ifmmode^\circ\else\textdegree\fi{}K in three different ways; two-point and four-point contacts in a planar geometry and in a capacitance configuration. The most extensive measurements conducted on the Al-${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$ and Sn-Sn${\mathrm{O}}_{2}$ systems showed that, over nine orders of magnitude in resistance the resistivity could be described by $\ensuremath{\rho}={\ensuremath{\rho}}_{0}{e}^{{(\frac{{T}_{0}}{T})}^{\frac{1}{n}}}$ with $n=4$ over a wide range of compositions in the Al-${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$ system. This resistivity behavior along with the current's voltage dependence and the ac resistivity measurements indicate that the conduction mechanism in such films may be similar to the thermally activated hopping mechanism described in other amorphous materials.