On the role of interface properties in the degradation of metalorganic vapor phase epitaxially grown Fe profiles in InP

Fe doping profiles in InP layers grown by low-pressure metalorganic vapor phase epitaxy (LP-MOVPE) were investigated by secondary ion mass spectroscopy. Different pre-treatments of the InP substrates proved to have substantially different effects on the Fe profiles which strongly indicate the relevance of underlying interfaces to dopant diffusion in subsequent layers, at least in the case of dopants occupying the group-III sublattice. We attribute the degradation of Fe profiles observed for some kinds of treatment to the emission of In interstitials from surfaces covered by oxides or other residues which are incompletely removed during the MOVPE preheat cycle. A favorable substrate preparation method for avoiding Fe profile degradation relies on etching by 5:1:1 H2SO4:H2O2:H2O at room temperature followed by 30 min deionized water rinsing.