Planar doped GaAs/AlAs superlattices were used to determine the energetic separation of Si DX states in AlGaAs compounds. The conduction mini-band energy was tuned by applying hydrostatic pressures. When a pressure was applied, the mini-band energy crossed over the deep levels while shallow levels were linked to the mini-band. Hall measurements which were performed on selectively doped superlattices permitted the ionization energies of the Si donor to be derived within the framework of a DX-donor model with negative correlation energy. Four deep states were found which were energetically separated from each other by about 0.040eV.

P.Sellitto, J.Sicart, J.L.Robert, R.Planel: Physical Review B, 1995, 51[23], 16778-84