An investigation was made of the diffusion of Ga into intrinsic n-type crystals doped with P to 5 x 1015/cm3, and into B pre-diffused extrinsic p-type crystals, using a closed tube diffusion technique. The profiles were determined by means of neutron activation and 72Ga radioactive tracer and sectioning techniques (table 43). Overall, the results at between 900 and 1050C could be described by:

D(cm2/s) = 2.9 x 101exp[-3.76(eV)/kT]

An observed increase in Ga diffusivity with hole concentration was explained in terms of a generalized monovacancy diffusion model in which the diffusion of ionized substitutional impurities was assumed to be controlled mainly by the concentration of vacancies of the opposite charge type.

Gallium Diffusions into Silicon and Boron-Doped Silicon. J.S.Makris, B.J.Masters: Journal of Applied Physics, 1971, 42[10], 3750-4

Table 43

Diffusion of Ga in Intrinsic and Extrinsic Crystals at 900 to 1050C