Evidence for substitutional-interstitial defect motion leading to DX behavior by donors in ${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As

A high-resolution Laplace-transform deep-level-transient spectroscopy has been used to study electon emission from the DX centers related to group-IV (silicon) and group-VI (tellurium) donor elements in ${\mathrm{Al}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As (0.25<x<0.76). This provides experimental evidence that substitutional-interstitial atom motion is responsible for DX behavior and for the associated metastability effects. The atom which is subjected to this transition is, for DX(Si), silicon itself, and so only one group of peaks is observed in the spectra; while for DX(Te), it can be either gallium or aluminum, producing two groups of peaks.