The relationship between F accumulation and Si-donor concentration in n-type InAlAs layers on a InP substrate was investigated by means of secondary ion mass spectroscopy. It was found, from the depth-profiles of F and Si donors in a periodic i-/n InAlAs sample, that F accumulated only in n-type InAlAs layers; passing through i-InAlAs layers. It was also found that the amount of F accumulation in an n-type InAlAs layer depended upon the Si doping concentration. The results could be explained by considering 2 states for F. In one state, F was bound to a Si donor and immobile while, in the other, it was free and could diffuse.

Fluorine Diffusion and Accumulation in Si Step-Doped InAlAs Layers A.Wakejima, K.Onda, A.Fujihara, E.Mizuki, M.Kanamori: Applied Physics Letters, 1998, 73[17], 2459-61