Epitaxial Growth of GaP/In_xGa_1-xP (x_In ≥ 0.27) Virtual Substrate for Optoelectronic Applications

Compositionally graded epitaxial semiconductor buffer layers are prepared with the aim of using them as a virtual substrate for following growth of heterostructures with the lattice parameter different from that of the substrates available on market (GaAs, GaP, InP or InAs). In this paper we report on the preparation of the step graded In_xGa_1-xP buffer layers on the GaP substrate. The final In_xGa_1-xP composition x_In was chosen to be at least 0.27. At this composition the In_xGa_1-xP band-gap structure converts from the indirect to the direct one and the material of such composition is suitable for application in light emitting diode structures. Our task was to design a set of layers with graded composition (graded buffer layer) and to optimize growth parameters with the aim to prepare strain relaxed template of quality suitable for the subsequent epitaxial growth.