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

Abstract

Several series of Te-doped ${\mathrm{GaAs}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{P}}_{\mathit{x}}$ layers grown by liquid phase epitaxy and vapor phase epitaxy are analyzed by deep-level transient spectroscopy (DLTS), photoluminescence, and thermally stimulated capacitance techniques. In addition to the well-established Te-DX center (trap A), DLTS spectra reveal two distinct peaks labeled B and C in the literature. These two traps, of unknown origin so far, but showing DX-like fingerprints, are actually donor-related DX centers generated by Si and S residual contamination. This finding, supported by results in Si- and S-implanted samples, clarifies a long standing question about the origin of these traps and their suggested relation to local environment effects. For the first time, to our knowledge, fingerprints (thermal and optical barriers) of the Si-related DX centers in ${\mathrm{GaAs}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{P}}_{\mathit{x}}$ 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 ${\mathit{GaAs}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathit{P}}_{\mathit{x}}$ alloys has to be made against recent published works, to avoid more confusion in the future. \textcopyright{} 1996 The American Physical Society.