CRYSTALLOGRAPHIC ORIENTATION DEPENDENCE OF IMPURITY INCORPORATION INTO III-V COMPOUND SEMICONDUCTORS GROWN BY METALORGANIC VAPOR-PHASE EPITAXY

This article presents a comprehensive study of the dependence of impurity incorporation on the crystallographic orientation during metalorganic vapor phase epitaxy of III-V compound semiconductors. We performed doping experiments for group-II impurities (Zn and Mg), group-VI impurities (Se and 0), and a group-IV impurity (Si form SiH4 and Si2H6). The host materials were GaAs, Ga0.51n0.5P, and (Al0.7Ga0.3)0.5In0.5P grown on GaAs substrates. We examined the doping efficiency on the surfaces lying between {100} and {111}A/B. Even though we grew epitaxial layers in a mass-transport-limited regime, the doping efficiency significantly depended on the orientation, indicating that the surface kinetics plays an important role in impurity incorporation. Comparing our results with other reports, we found that acceptor impurities residing on the group-III sublattice and donor impurities residing on the group-V sublattice, respectively, have their own distinctive orientation dependence. Si donors exhibit orientation dependences which are either negligible or are similar to group-VI donors, depending on the growth conditions. We constructed a model for the orientation dependences, considering atomic bonding geometries between impurity adsorbates and adsorption sites.