STUDIES ON THE ETCHING AND ANNEALING BEHAVIOR OF ALPHA-AL2O3(1012) SURFACES BY REFLECTION ELECTRON-MICROSCOPY

The effects of chemical etching and annealing on α-AI2O3 (1̄012) surfaces have been studied using reflection electron microscopy (REM). Cleaved surfaces exhibit domains the contrast of which depends on whether the terminating ion is aluminium or oxygen. It is further observed that chemical etching followed by annealing at 1100°C gives atomically flat surfaces. It is also demonstrated that the technique of REM can provide very useful information on surface diffusion processes. A new method for measuring surface diffusion coefficients and binding energies is proposed. The surface diffusion coefficient of α-Al2O3(1̄012) determined to be 5.7 × 10-1 cm2 s-1 at 1100°C and 2.9 × 10-13 cm2 s 1 at 1150°C, giving D0 = 8.7 × 10-13 cm2 s approximately 5.5 eV. © 1991