The interdiffusion of AlGaAs/GaAs, at temperatures ranging from 750 to 1150C (figure 5), was found to be described by:

D (cm2/s) = 0.2 exp[-3.6(eV)/kT]

It was shown that, in spite of the range of activation energies quoted in the literature, all of the data could be described by assuming a single activation energy. By using this value of the activation energy, fitting the published data and determining a pre-exponential factor for each data point, it was found that that the published data fell into 2 clusters. One cluster contained samples which had been annealed under a Ga-rich overpressure and the other cluster contained the results of As-rich or capped annealing. This could be explained by assuming that diffusion in all cases was governed by a single mechanism; that of vacancy-controlled second-nearest neighbor hopping.

S.F.Wee, M.K.Chai, K.P.Homewood, W.P.Gillin: Journal of Applied Physics, 1997, 82[10], 4842-6

Figure 5

Interdiffusivity of GaAs and AlGaAs