A photometric method was used to study the substitutional diffusion of Al and Ga in polycrystalline samples. In both cases, the diffusion rates increased with the surface concentration, up to a limiting value. The value for Al was 3mgAl/gZnO . At this, and higher, concentrations, the data at 780 to 890C could be described by:

D (cm2/s) = 5.3 x 10-2exp[-2.74(eV)/kT]

The limiting Cu concentration was 25mg/gZnO. At this, and higher, concentrations, the data at 730 to 800C could be described by:

D (cm2/s) = 3.6 x 104exp[-3.75(eV)/kT]

Diffusion of Al and Ga in ZnO. Norman, V.J.: Australian Journal of Chemistry, 1969, 22[2], 325-9