[en] Engineered or ‘virtual’ substrates are of interest to extend the range of epitaxially-grown semiconductor heterostructures available for device applications. To this end, elastically strain-relaxed square features up to 30 µm in size and having an in-plane lattice constant as much as 0.49% larger than the lattice constant of GaAs were fabricated from MOCVD-grown GaAs/In_0.08Ga_0.92As/GaAs heterostructures by the in-place bonding method, using either AlAs or Al_0.7Ga_0.3As as the sacrificial layer. TEM images show that the solution-bonded interface is flat with a network of sessile edge dislocations that accommodates the different in-plane lattice constants of the feature and the GaAs substrate and a small rotation of the bonded features. Micro-Raman spectroscopy, which has a spatial resolution of ∼1 µm, was shown to be useful for characterizing lattice mismatch strain ≥ 0.0023, i.e. with an order of magnitude lower sensitivity than high-resolution XRD. (paper)