The compositional dependence of the energy levels of DX centers in InAlAs/InGaAs heterostructures were determined by applying Hall-effect and persistent photoconductivity methods to gated Hall-bar test structures. The energy of the DX center, relative to the average of the main conduction-band minima of the Brillouin zone for In mole fractions of 0.1 to 0.34, was equal to about 0.3eV. At In mole fractions above 0.4, the DX center was resonant with the conduction band.

DX centers in InxAl1-xAs H.Sari, H.H.Wieder: Journal of Applied Physics, 1999, 85[6], 3380-2