Method for design of epitaxial layer and substrate structures for high-quality epitaxial growth on lattice-mismatched substrates

A method for forming low defect density epitaxial layers on lattice-mismatched substrates, comprising the steps of:

• a) choosing a first epilayer and a top substrate layer for epitaxial growth;
• b) determining a first lattice constant and a first thermal expansion coefficient of said first epilayer;
• c) determining a second lattice constant and a second thermal expansion coefficient of said top substrate layer;
• d) bonding an additional substrate layer to said top substrate layer to form a composite substrate so that said first epilayer has either positive lattice mismatch and negative or zero thermal mismatch to said composite substrate, or negative lattice mismatch and positive or zero thermal mismatch to said composite substrate;
• and
• e) choosing a buffer layer which is lattice matched to said first epilayer to be deposited on said composite substrate before depositing said first epilayer, wherein
• said buffer layer has positive thermal mismatch to said composite substrate when said buffer layer and said top substrate layer have positive lattice mismatch, and
• said buffer layer has negative thermal mismatch to said composite substrate when said buffer layer and said top substrate layer have negative lattice mismatch.