Effect of InGaAs interlayer on the properties of GaAs grown on Si (111) substrate by molecular beam epitaxy

Abstract

High-quality GaAs films have been epitaxially grown on Si (111) substrates by inserting an InxGa1−xAs interlayer with proper In composition by molecular beam epitaxy (MBE). The effect of InxGa1−xAs (0 < x < 0.2) interlayers on the properties of GaAs films grown on Si (111) substrates by MBE has been studied in detailed. Due to the high compressive strain between InGaAs and Si, InGaAs undergoes partial strain relaxation. Unstrained InGaAs has a larger lattice constant than GaAs. Therefore, a thin InGaAs layer with proper In composition may adopt a close lattice constant with that of GaAs, which is beneficial to the growth of high-quality GaAs epilayer on top. It is found that the proper In composition in InxGa1−xAs interlayer of 10% is beneficial to obtaining high-quality GaAs films, which, on the one hand, greatly compensates the misfit stress between GaAs film and Si substrate, and on the other hand, suppresses the formation of multiple twin during the heteroepitaxial growth of GaAs film. However, when the In composition does not reach the proper value (∼10%), the InxGa1−xAs adopts a lower strain relaxation and undergoes a lattice constant smaller than unstrained GaAs, and therefore introduces compressive stress to GaAs grown on top. When In composition exceeds the proper value, the InxGa1−xAs will adopt a higher strain relaxation and undergoes a lattice constant larger than unstrained GaAs, and therefore introduces tensile stress to GaAs grown on top. As a result, InxGa1−xAs interlayers with improper In composition introduces enlarged misfit stress to GaAs epilayers grown on top, and deteriorates the quality of GaAs epilayers. This work demonstrates a simple but effective method to grow high-quality GaAs epilayers and brings up a broad prospect for the application of GaAs-based optoelectronic devices on Si substrates.