Temperature Dependence of Electron-Bombardment-Induced Conductivity in MgO

The dependence upon temperature of the electrical conductivity induced in thin single crystals of MgO by bombardment with high-energy electrons which pass through the targets with negligible energy loss has been measured over the temperature range 200^∘{} K-600^∘{} K. The experimental data are in accord with a theory which ascribes the observed decrease in conductivity as the temperature is raised to the predicted variation in the mobility of the charge carriers. The effects of scattering by both the optical modes and the acoustical modes of vibration of the lattice must be taken into account, since neither the exp(ΘT) relationship resulting from the first type of interaction nor the T^-3/2 law arising from the second individually fits all of the data. The experiments also indicate that the concentration of trapping centers remains essentially constant over the temperature range investigated. The lifetime of the carriers is approximately 5×{}10^-10 sec, and the trap density is estimated to be 10¹⁷-10¹⁸ cm^-3.