Cathodoluminescence study of Si complex formation in self-doped and intentionally Si-doped GaAs conformal layers

An Si complex formation is observed in unintentionally doped as well as n-type doped GaAs layers grown laterally on GaAs seeds deposited on (100) Si substrates. The free carrier concentration was accurately assessed by previous Raman studies. Particularly interesting was the observation of a doped stripe nearby the GaAs seed in the unintentionally doped layers. In this work the formation of the complexes in both kinds of doped samples was analysed by means of SEM-cathodoluminescence (CL) studies. Different bands, indicative of the presence of more than one Si-related transition, have been observed in the infrared spectral region. The distribution of some of the related complexes at the different depths along the growth axis was analysed by depth-resolved CL. The nature of the emission levels has been investigated by power dependent CL studies, allowing to correlate them to DAP transitions. The Si autodoping origin of the doped stripes on the unintentionally doped samples was also confirmed.