Influence of annealing on the electrical conductivity of single crystals of Cu₂O

Abstract

A series of conductivity measurements were made on single crystals of Cu 2 O from 20 to 840 °C to explain the various activation energies which appear at different temperatures and oxygen pressures. Crystals were annealed in the 10 −8 and 10 −4 Torr region in the stability ranges of Cu 2 O, Cu, and CuO at various temperatures. For the low-temperature activation energies ranging from 0.60 to 0.26 eV, an excellent agreement with the empirical Meyer–Neldel rule was found. The highest activation energy of 1.12 eV in the 570 to 680 °C range at 10 −8 Torr is associated with the boundary between the two stable phases Cu and Cu 2 O. The changes in defect concentration are ascribed to the mechanism of self-compensation. The energy-level diagram proposed by Bloem is adequate to explain the present results.