ELECTRONIC TRANSPORT IN THERMALLY GROWN CR2O3

Electrical conductivity of thermally grown Cr2O3 has been measured as a function of temperature and over a range of oxygen partial pressures from that of air to that of the Cr/Cr2O3 equilibrium. The conductivity showed p-type behavior over the range of the present investigation. At temperatures above 1000°C, the conductivity values were independent of oxygen partial pressure and indicated intrinsic semiconductor behavior. The mobility of holes, determined by measuring conductivity at fixed compositions (i.e., fixed δ in Cr2-δO3), increased with temperature. This behavior can be attributed to hopping-type conduction. For δ ∼ 10-5, the activation energy for hole hopping was 0.248 eV, and the calculated hole mobilities were 5.4x10-2 and 2.4x10-1 V/cm2 · s at 500 and 1000°C, respectively. The oxidation kinetics of Cr were determined by measuring the electrical conductivity and electromotive force across the oxide layer at 875°C. The result agreed well with the oxidation data obtained in thermogravimetric tests. © 1990 Plenum Publishing Corporation.