Ga0.5In0.5P/GaAs interfaces by organometallic vapor-phase epitaxy

Organometallic vapor phase epitaxial growth of most III–V compounds is normally performed under group-V-rich conditions, making it difficult to form an abrupt interface during a change of group V species. The Ga0.5In0.5P/GaAs interface is of interest because it offers a potential advantage over AlGaAs/GaAs selectively doped structures by reducing the deep-level donor problem. In this communication, formation of the Ga0.5In0.5P/GaAs interface during low-pressure organometallic vapor phase epitaxial growth is studied by comparing a series of three superlattices grown using different interface formation techniques. Continuous growth, growth stop under group V gas, and growth stop followed by a purge of all reactants are analyzed by Raman scattering, transmission electron microscopy (TEM), and 4-K photoluminescence. All superlattices show good TEM contrast between layers. The growth stop is found to reduce both P and In intermixing into the GaAs layers, relative to the continuously grown superlattice. The purging step further reduces In intermixing, but also results in decomposition of the Ga0.5In0.5P layers, which increases P carryover into the GaAs layers.