Epitaxial growth of InAs on semi-insulating GaAs was a subject of various attempts to reduce the influence of the ~7% lattice mismatch on the InAs layer properties. The most cost effective and promising method appears to be the growth of low temperature buffer (LTB) InAs layer at ~400°C followed by a thick InAs layer at ~600°C. There is a scarcity of available information about the structural properties of the LTB layers, their background conductivity type and level of doping. We have found that a predominant part of the threading dislocations generated at the interface annihilate within the first 400nm.The average misfit dislocation spacing is 6.15nm, proving that the LTB InAs/GaAs interface is nearly completely relaxed. XRD measurements have revealed a well pronounced deformation decrease in the LTB layers for thicknesses above 300nm. The LTB InAs layer is n-type with carrier concentration of the order of 5×1016cm−3 and can be additionally doped with Te and hence can serve as a bottom contact layer. The morphology of unintentionally doped InAs layer grown at 600°C upon the LTB shows sub-nanometer flatness and carrier concentration of the order of 5×1015cm−3.

Elastic accommodation of heteroepitaxial layers beyond their critical thickness is crucial for the reduction of misfit dislocations. One approach is to utilize substrate engineering in order to delay plastic relaxation. In this work, pore networks were introduced electrochemically in GaAs substrates in order to modify their mechanical responses. In, Ga1-xAs epilayers with nominal indium contents up to x = 0.20 were then deposited by MOVPE, and were compared to similar epilayers grown on nonporous GaAs. Strain relaxation and defect introduction were studied by TEM observations, x-ray diffraction, and photoluminescence measurements. It was found that the porous substrates acted to reduce the density of misfit dislocations, thereby increasing the epilayer critical thickness. The InGaAs epilayers retained a significantly higher amount of elastic strain compared to ones grown on nonporous GaAs. The onset of plasticity was mediated by the pores, which acted as nucleation sites for 60 dislocations that glided toward the interface. (C) 2014 Elsevier B.V. All rights reserved.

We report on the electrochemical preparation of GaAs porous substrates, their heat treatment in As rich environment and their overgrowth by metalorganic vapor phase epitaxy (MOVPE). The goal is to demonstrate that porous substrates are capable of accommodating strain at the interface with lattice mismatched In(x)Ga(1-x)As layers.

We report on the electrochemical preparation of GaAs porous substrates, their heat treatment in As rich environment and their overgrowth by metalorganic vapor phase epitaxy (MOVPE). The goal is to demonstrate that porous substrates are capable of accommodating strain at the interface with highly lattice mismatched In(x)Ga(1-x)As layers.