Quality-enhanced In0.3Ga0.7As film grown on GaAs substrate with an ultrathin amorphous In0.6Ga0.4As buffer layer

Abstract

Using low-temperature molecular beam epitaxy, amorphous In0.6Ga0.4As layers have been grown on GaAs substrates to act as buffer layers for the subsequent epitaxial growth of In0.3Ga0.7As films. It is revealed that the crystallinity of as-grown In0.3Ga0.7As films is strongly affected by the thickness of the large-mismatched amorphous In0.6Ga0.4As buffer layer. Given an optimized thickness of 2 nm, this amorphous In0.6Ga0.4As buffer layer can efficiently release the misfit strain between the In0.3Ga0.7As epi-layer and the GaAs substrate, trap the threading and misfit dislocations from propagating to the following In0.3Ga0.7As epi-layer, and reduce the surface fluctuation of the as-grown In0.3Ga0.7As, leading to a high-quality In0.3Ga0.7As film with competitive crystallinity to that grown on GaAs substrate using compositionally graded InxGa1-xAs metamorphic buffer layers. Considering the complexity of the application of the conventional InxGa1-xAs graded buffer layers, this work demonstrates a much simpler approach to achieve high-quality In0.3Ga0.7As film on GaAs substrate and, therefore, is of huge potential for the InGaAs-based high-efficiency photovoltaic industry.