Dependence of electrical conductivity of β-Ga2O3 ceramics on oxygen partial pressure and formation of dislocations

The electrical conductivity of porous and high-purity β-Ga2O3 ceramics was measured as a function of oxygen partial pressure, po2, at 700 to 900 °C. In the high po2 range, the conductivity was proportional to about −1/4th power of po2, while in the lower po2 range less than about 10−5 atm its exponent was −0.1 to −0.13. This suggests that different types of defects were formed at high and low po2. The point defect of doubly ionized interstitial gallium ion causes the exponent of −1/4, the same value of the experiment in high po2. When po2 was changed, the electrical conductivity first changed sharply, followed by a slow change, suggesting some migrations and/or formation of crystalline defects, and so on. In the Ga2O3 samples, many dislocations, with density of about 1012 cm−2, were observed. As the source of carriers, line defects, such as dislocations, should be considered as well as point defects.