Direct evidence of the D X center link to the L-conduction-band minimum in GaAlAs

Abstract
Hydrostatic pressure techniques together with deep level transient spectroscopy (DLTS) measurements have shown that the Si-DX center in GaAlAs is linked to the L-conduction-band minimum. When hydrostatic pressure is applied to a 74% Al content sample, an exponential reduction of the DLTS signal is observed. This exponential dependence with pressure arises from the reduction of the DX filling factor (electron occupancy) due to the increasing X-L energy difference with pressure. Our results, together with previous data, also show that the capture barrier height originating from the lattice relaxation is an intrinsic parameter of both the material and the donor species, that does not depend on Al content or conduction-band structure.