The diffusion coefficient in Zn-doped material was accurately determined, at 90 to 150C, for doping levels (C) of 3.4 x 1016 or 2.6 x 1017/cm3. Effective diffusion coefficients (table 20) were directly measured from the profiles and could be described by:
DC (/s cm) = 8 x 1020 exp[-1.36(eV)/kT]
The activation energy was close to the dissociation energy of the Zn-H complex, while the effective diffusivity was inversely proportional to the acceptor concentration. The effective diffusivity therefore exhibited the same temperature dependence as the Zn-H dissociation kinetics. Diffusion under the present conditions was controlled entirely by the association and dissociation of H with Zn atoms, and was independent of the intrinsic diffusivity of H in GaAs layers.
Trap-Limited Diffusion of Hydrogen in Zn-Doped GaAs M.C.Wagener, J.R.Botha, A.W.R.Leitch: Physical Review B, 1999, 60[3], 1752-8
Table 20
Effective H Diffusivities in Zn-Doped GaAs
Temperature (C) | Zn (/cm3) | D (cm2/s) |
89 | 3.4 x 1016 | 2.17 x 10-15 |
114 | 3.4 x 1016 | 3.72 x 10-14 |
100 | 2.6 x 1016 | 1.59 x 10-15 |
123 | 2.6 x 1016 | 1.43 x 10-14 |
130 | 3.4 x 1016 | 2.01 x 10-13 |
148 | 3.4 x 1016 | 1.18 x 10-12 |