Investigation of dislocation propagation and confinement in GaAs epilayers grown on Si substrates using InGaAs-GaAsP strained layer superlattices

Abstract

The heteroepitaxial growth of GaAs on Si has been recognized as a viable technology towards achieving the monolithic integration of III-V compound based optoelectronic components and Si devices. Both metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) growth techniques have been widely employed to achieve heteroepitaxial growth However, as a result of the lattice and coefficient of thermal expansion mismatch that exists between the Si substrate and GaAs epilayer, a high density of defects propagate into the GaAs epitaxial film. In an attempt to reduce the density of these defects to a acomparable level for device fabrication (< 104 cm-2), the use of a strained layer superlattice (SLS) has been advocated as an appropriate defect confinement layer. A judicious choice of SLS is InxGa1-xAs-GaAs1-yPy (y=2x)2 whose average lattice constant is lattice matched as a whole to the GaAs epilayer. Indeed, by using this particular SLS structure, a high level of elastic strain and an infinite number of semiconductor layers can be selected to force the dislocations to glide to the edge of the substrate.