Defect Engineering Through Substrate Design

摘要

A comprehensive program in the control of extended defects associated with the growth of large lattice-mismatched materials was undertaken. This program was aimed at understanding the interaction of extended defects with stress that is intentionally introduced into a substrate structure and develop processes for the growth of large lattice mismatched materials with a substantially reduced defect density over large substrate areas. The narrow band gap semiconductors, GaSb and InAs, were used in these studies. The application of a lateral epitaxial overgrowth technique (LEO) led to a dramatic and unexpected reduction in defect density when the mask openings are restricted to less than 1 micrometer. Our measurements indicate an appropriately engineered substrate can lead to dramatic changes in the defect structure leading to the isolation of lattice-mismatched based dislocations to the interface region leading to strong reduction in the dislocation density in the overlying layers. A detailed characterization of the defect structure demonstrated defect reduction in the LEO substrates.