Donor-related states, in Si-doped material with Al compositions that ranged from 0.30 to 0.59, were investigated by means of capacitance measurements. In addition to the stable Si-DX state, 2 metastable states of the Si donor were detected. The shallower of the 2 metastable states was attributed to a X-conduction band-related effective-mass state that arose from substitutional Si on group-III sites. The deeper state was suggested to be related to a donor configuration that was different to the substitutional configuration and to the configuration of the DX state.

Y.B.Jia, H.G.Grimmeiss: Journal of Applied Physics, 1996, 80[8], 4395-9