Lattice engineered substrates using lateral oxidation of aluminum arsenide

This thesis documents the invention, development and demonstration of a new approach to relaxed heteroepitaxy---the lattice engineered substrate (LES). This approach is based on the process of lateral oxidation of Al-containing III-V compound semiconductors. The process of lateral oxidation besides changing a crystalline semiconductor to an amorphous oxide, converts a rigid epitaxial interface to a porous oxide/semiconductor interface. This results in significant structural changes in the semiconductor structure. The most significant of these are the reduction in thickness of the oxidizing semiconductor and the relaxation of strain in lattice-mismatched (strained) semiconductor overlayer. This results in an epitaxial template with a different lattice constant that is mechanically supported on a commercially available binary III-V substrate, effectively generating a new (quasi)-substrate.;One of the main prerequisites for a lattice-engineered substrate is the growth of thick highly strained semiconductor overlayers (like InGaAs on GaAs) with a low threading dislocation density. This is achieved by growth at a low temperature and by maintaining the growth in a layer-by-layer mode. The strain relaxation in these overlayers upon lateral oxidation is dependent on the oxidation temperature and the lattice mismatch between the strained overlayer and the substrate. The enhanced strain relaxation upon oxidation is attributed to the stress generated during the lateral oxidation process and the removal of misfit dislocation segments at the strained overlayer - oxide interface.;The structural, electronic and optical properties of epitaxial layers grown on lattice-engineered substrates is sensitive to surface preparation techniques that are used prior to regrowth. Pure thermal desorption of a lattice-engineered substrate that is protected with a thin GaAs cap layer was found to be the best technique. Epitaxial layers grown on lattice-engineered substrates had higher strain relaxation than those grown directly on GaAs substrates. InGaAs pn junction diodes grown on lattice-engineered substrates had lower reverse leakage current that can be attributed to lower dislocation density. The GaAs based lattice-engineered substrate technology enables the growth of high band-offset quantum wells, which are necessary for uncooled operation of long wavelength lasers. Room temperature photoluminescence was observed at 1.3 mum from InGaAs and GaAsSb based multiple quantum wells grown on GaAs lattice-engineered substrates.