Microstructure of epitactically grown GaAs/ErAs/GaAs

A series of GaAs/ErAs/GaAs epilayer heterostructures has been grown on (100)GaAs substrates by molecular beam epitaxy and characterized by high-resolution transmission electron microscopy and Rutherford backscattering measurements. Good epitaxy of the ErAs on the GaAs is demonstrated. The top GaAs layer is usually epitactically aligned with ErAs/GaAs in most areas; however, growth of (111)GaAs on (100)ErAs has also been observed. Small grains are present in the top GaAs layer which are twinned on {111} with respect to epitactic grains. These give rise to GaAs {122}/ErAs(100) phase boundaries. The {122} oriented GaAs grains do not continue throughout the GaAs growth but are overgrown by the neighboring epitactic grains.