ABSTRACT:

(In,Ga)As/GaAs quantum wells (QWs) are successfully fabricated via a thermally induced structural transition from deposited amorphous material to epitaxial films, also known as solid-phase epitaxy (SPE). Although exact processes occurring during the epilayer formation are unknown, it is shown that the method allows the fabrication of high quality QWs with abrupt and symmetric composition profiles. As discussed here, the analysis of the chemical interface (composition profile) of the SPE-grown QWs, and its comparison with the element profiles of similar heterostructures grown by conventional molecular beam epitaxy (C-MBE) provides further insight into the SPE processes. In particular, we find that regardless of the fabrication method (SPE vs C-MBE), the smooth variation of the element concentration with the position across the interface is remarkably well described by a sigmoidal function. Such functional dependence is determined by fundamental processes occurring during the growth; thus suggesting that the basic mechanisms of interface formation are similar in SPE and C-MBE. Finally, the effect of self- and post-growth thermal annealing on SPE QWs is also discussed.