| 摘要 |
Pseudomorphic and dislocation free heteroepitaxial structures are formed in which pseudomorphic and heteroepitaxial layers of any desired thickness are grown on thin, free-standing substrates. In the case of pseudomorphic structures, the substrates are chosen to have a thickness less than the critical thickness above which misfit dislocations will form between the pseudomorphic layers and the substrate. Use of thin substrates in this manner prevents the overall strain energy between the two layers from ever becoming large enough to generate misfit dislocations, regardless of the pseudomorphic layer thickness. This concept can also be employed in the formation of defect free heteroepitaxial layers. If a heteroepitaxial layer is grown on a very thin substrate, an effect known as dislocation gettering will cause any dislocations between the two layers to propagate into the substrate, thus leaving the heteroepitaxial layer defect free. Multiple layer superlattice structures can also be formed which either have a very large lattice mismatch between the top and bottom layers, or strain compensation between the layers and the bottom substrate.
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