Using a critical composition grading technique to deposit InGaAs epitaxial layers on InP substrates

摘要

A method for growing In_xGa_1xAs epitaxial layer on a lattice mismatched InP substrate calls for depositing by organo-metallic vapor phase epitaxy, or other epitaxial layer growth technique, a plurality of discreet layers of InAs_yP_1y over an InP substrate. These layers provide a buffer. Each succeeding buffer layer has a distinct composition which produces less than a critical amount of lattice mismatch relative to the preceding layer. An In_xGa_1xAs epitaxial layer is grown over the buffer wherein 0.53x0.76.;A resulting InGaAs structure comprises an InP substrate with at least one InAsP buffer layer sandwiched between the substrate and the InGaAs epitaxial layer. The buffer layer has a critical lattice mismatch of less than 1.3% relative to the substrate. Additional buffer layers will likewise have a lattice mismatch of no more than 1.3% relative to the preceding layer. The number of buffer layers is determined by the resulting bandgap desired in the InGaAs epitaxial layer, which, in turn, determines the composition of the In_xGa_1xAs epitaxial layer, and thus, the lattice mismatch.