In-place bonding of III-V semiconductor heterostructures

Elastically strain-relaxed GaAs/In$_{0.08}$Ga$_{0.92}$As/GaAs heterostructures on GaAs(001) substrates were fabricated. Pseudomorphic heterostructures grown by MOCVD were patterned using conventional photolithography and a sacrificial AlAs layer was removed by selective etching. As etching proceeds, the structure is released from the substrate, elastic strain relaxation occurs and the strain-relaxed structures are weakly bonded in-place to the substrate. The bond between the structure and the substrate was then strengthened by annealing under conditions similar to those used for whole wafer bonding of GaAs. The strain, composition and thickness of the layers were determined using high resolution X-ray diffraction and the sample surface quality was examined using atomic force microscopy. The degree of strain relaxation of the InGaAs layer is determined by the relative thickness of the GaAs and InGaAs layers in agreement with a force balance model. The increase in the in-plane lattice parameter of the bonded structures as compared to GaAs is 0.25-0.44%.