Fifty-period superlattices of C delta-doped layers were grown by using metalorganic vapor phase epitaxy. The samples were annealed (600C, 0.25h) in N in order to remove all H. After annealing, no H-CAs pairs could be detected by using infra-red localized vibrational mode spectroscopy, and an increase in the carrier concentration was observed. By comparing measured and simulated X-ray data, the C concentration and layer thickness in GaAs were found to be 2 x 1020/cm3 and 1nm, respectively. In the case of AlAs, there was a similar C concentration but it was spread over a thickness of 3.5nm. The presence of H-CAs pairs in GaAs was found to cause a lattice contraction which was 40% of that which was produced by the same concentration of isolated CAs.

L.Hart, B.R.Davidson, J.M.Fernández, R.C.Newman, C.C.Button: Materials Science Forum, 1995, 196-201, 409-14