“Compliant” twist-bonded GaAs substrates: The potential role of pinholes

Abstract

By twist wafer bonding, thin (100) GaAs layers were transferred onto (100) GaAs handling wafers in order to fabricate structures like those suggested in the literature as “compliant universal substrates.” Heteroepitaxial InP and InGaAs films were grown on the GaAs twist-bonded layers. Twisted and untwisted grains of the epitaxial film with diameters from 0.1 to several μm without threading dislocations were observed by transmission electron microscopy. Twisted grains grew on the twist-bonded layer, while the untwisted grains grew directly on the GaAs handling wafer and were caused by pinholes in the twist-bonded GaAs layer. It is suggested that the lateral limitation of the epitaxial growth of grains on the thin twisted GaAs layer caused by the presence of pinholes reduces the density of threading dislocations in the strain-relaxed film and might be a mechanism for the observed low density of threading dislocations in lattice-mismatched epitaxial films grown on twist-bonded “compliant universal substrates.”