HALL EFFECT AND ELECTRICAL CONDUCTIVITY OF Cu₂O MONOCRYSTALS

Abstract

Hall-effect and electrical conductivity measurements were performed on Cu 2 O single crystals both before and after heating the samples in vacuo at temperatures ranging from 200 °C to 800 °C. Both the absolute values of the mobility and the conductivity, as well as their temperature dependence, were found to be strongly altered by the heating process. Room-temperature conductivities usually dropped from 10 −6 ohm −1 cm −1 to 10 −8 ohm −1 cm −1 , while the mobility increased from about 30 to 100 cm 2 V −1 sec −1 after heating to 300 °C. At the same time, the activation energies for the conductivity increased and a region of exponential temperature dependence for the mobility showed up. Vacuum heating above 800 °C again changed the sample characteristics quite drastically and appeared to stabilize them with respect to their environment with different atmospheres. Reproducibility for a given sample and from sample to sample could be obtained only after heating the samples in vacuo. The results are compared with previous investigations, and it is suggested that different surface conditions or thermal histories could account for the wide variety of data found in the literature.