In molecular layer epitaxy, Se existed as an interstitial atom and behaved as a diffusion source. During growth, the diffusion of doped Se into GaAs was affected by the supply pressure of AsH3. A higher amount of AsH3, when supplied during the growth of an undoped layer in an n++-i structure, reduced the diffusion of Se. A lower amount of AsH3, when supplied during the growth of an n++ layer, reduced the diffusion of Se from the n++ layer to the i layer. The stoichiometry of i and n++ layers affected the diffusion of interstitial Se in different ways.

Diffusion Control of Dopant from Heavily Se Doped n-Type GaAs Layers Grown by Molecular Layer Epitaxy J.Nishizawa, T.Kurabayashi: Japanese Journal of Applied Physics - 1, 1999, 38[11], 6193-6