Behavior of silicon-, sulfur-, and tellurium-related DX centers in liquid-phase-epitaxy and vapor-phase-epitaxy GaAs1-xPx alloys

Several series of Te-doped GaAs1-xPx layers grown by liquid phase epitaxy and vapor phase epitaxy are analyzed by deep-level transient spectroscopy (DLTS), photoluminescence, and thermally stimulated capacitance techniques, In addition to the well-established Te-DX center (trap A), DLTS spectra reveal two distinct peaks labeled B and C in the literature. These two traps, of unknown origin so far,but showing DX-like fingerprints, are actually donor-related DX centers generated by Si and S residual contamination. This finding, supported by results in Si- and S-implanted samples, clarifies a long standing question about the origin of these traps and their suggested relation to local environment effects. For the first: time, to our knowledge, fingerprints (thermal and optical barriers) of the Si-related DX centers in GaAs1-xPx have been established. A warning is given about the high risk of experimental data misinterpretation in cases where residual contamination is present. A clear and strong statement about the existence of Te-DX centers in GaAs1-xPx alloys has to be made against recent published works, to avoid more confusion in the future.