Iron-aluminium pair reconfiguration processes in SiGe alloys

Abstract

For the iron-aluminium pair in silicon it is possible to observe a deeper and stable first-nearest neighbour configuration and a shallower metastable more distant pair. Depending on sample cooling conditions it is possible to convert some of the stable pairs to metastable ones in a fully reversible process. The conversion process is a single jump of the iron between two neighbouring interstitial sites. In this study we have analysed how the electronic levels of the pair in both configurations are modified in SiGe by the alloying effects. We have also investigated to what extent the presence of germanium atoms in the crystal matrix affects the dynamics of the single iron jump process. These studies have been performed using Czochralski-grown unstrained aluminium-doped Si_1−x Ge _x crystals (0 < x < 0.056). Local environments of the Fe_iAl_s pairs have been observed as structures seen in high-resolution Laplace DLTS spectra. It has been observed that the energy separation of the main and subsidiary peaks are similar for both pair configurations which indicates that for iron the alloy effect is similar for both its interstitial positions.