Investigation of cross-hatch in In0.3Ga0.7As pseudo-substrates

Metamorphic buffer layers offer a wide variety of lattice constants for substrate on which devices can be grown. However, almost in all cases, the surface of the pseudo-substrate contains striations which are known as “cross-hatch.” Although, it is accepted that this surface undulation is related with the underlying gridlike misfit dislocations (MDs), the exact correlation is still to be determined. In this article, degree of polarization of photoluminescence maps and atomic force microscopy were used to analyze the correlation between surface undulation and the underlying strain field of the pseudo-substrate. From the correlation, it can be said that the surface undulation is not formed after MD nucleation, but MDs form in some of the troughs of the undulation.