The diffusion of Si was studied in <100> GaAs which had been implanted with 40keV 30Si+ ions. Profiles were determined by means of secondary-ion mass spectrometry and nuclear resonance broadening techniques. The implanted samples were subjected to annealing in Ar at 650 to 850C. Two independent Si diffusion mechanisms were observed. A concentration-independent diffusion, seen as a broadening of the initial implanted distribution, was very slow and was attributed to Si atoms that diffused interstitially. A concentration-dependent diffusivity with low solubility, was quantitatively explained in terms of the diffusion, via vacancies, of Si atoms on the Ga and As sub-lattices. The concentration-independent diffusion of Si was described by:

D (cm2/s) = 1.23 x 10-7 exp[-1.72(eV)/kT]

Intrinsic diffusion via neutral Ga vacancy complexes, triply negatively charged As vacancy complexes and triply negatively charged Ga vacancy complexes was described by:

Ga vacancy complexes:     D (cm2/s) = 3.74 x 10-3 exp[-2.60(eV)/kT]

charged As vacancy complexes:     D (cm2/s) = 4.67 x 10-5 exp[-2.74(eV)/kT]

charged Ga vacancy complexes:     D (cm2/s) = 5.92 x 10-8 exp[-2.28(eV)/kT]

T.Ahlgren, J.Likonen, J.Slotte, J.Räisänen, M.Rajatora, J.Keinonen: Physical Review B, 1997, 56[8], 4597-603

The best linear fits to the solute diffusion data ([46] to [92]) yield:

Be: Ln[Do] = 0.40E – 26.7 (R2 = 0.75); Cd: Ln[Do] = 0.55E – 50 (R2 = 0.61);

Co: Ln[Do] = 0.12E – 3.8 (R2 = 0.06); Fe: Ln[Do] = 0.36E – 20.2 (R2 = 0.66)

Ga: Ln[Do] = 0.19E – 15.5 (R2 = 0.79); S: Ln[Do] = 0.46E – 29.9 (R2 = 0.99)

Si: Ln[Do] = 0.43E – 31.6 (R2 = 0.42); Zn: Ln[Do] = 0.52E – 29.9 (R2 = 0.90)