It was found that the Al diffusion region in p-type material could be seen as a dark region in scanning electron microscopic images. The Al was diffused using a wide range of annealing temperatures and times. It was found that the data could be described by:

D (cm2/s) = 2.0 x 101 exp[-1.9(eV)/kT]

Diffusion Properties of Al in ZnTe Substrates. M.Hanafusa, K.Sato, A.Noda, A.Arakawa, Y.Matsuda, O.Oda: Journal of Applied Physics, 2001, 89[3], 1989-90