The co-evaporation of B2O3 during Si molecular beam epitaxial growth at temperatures of between 540 and 800C was used to prepare superlattice structures with B concentrations which ranged from 3 x 1018 to 3 x 1020/cm3. The superlattices were then annealed and studied by using secondary ion mass spectrometry, electrochemical profiling and cross-sectional transmission electron microscopy. It was found that an appreciable redistribution of B, at high B concentrations, occurred before annealing when the growth temperature was greater than 700C. The diffusivity of B in the layers was found to depend markedly upon the growth temperature (table 23).

Annealing Studies of Highly Doped Boron Superlattices. T.E.Jackman, D.C.Houghton, J.A.Jackman, M.W.Denhoff, S.Kechang, J.McCaffrey, A.Rockett: Journal of Applied Physics, 1989, 66[5], 1984-92

Table 23

Diffusion of B in Si Molecular Beam Epitaxial Layers

as a Function of the Growth Temperature