DX centers in InxAl1-xAs

The composition dependence of the energy levels of the DX centers in InxAl1-xAs/InyGa1-yAs heterostructures have been determined by means of Hall effect and persistent photoconductivity measurements made on gated Hall bar test structures, primarily in the indirect portion of the fundamental band gap of InxAl1-xAs. The energy of the DX center relative to the average of the main conduction band minima of the Brillouin zone, in the composition range, 0.1 less than or equal to x less than or equal to 0.34, is E(DX)similar to 0.3 eV; for x>0.4 the DX center is resonant with the conduction band. (C) 1999 American Institute of Physics. [S0021-8979(99)00206-6].