Abstract
Transmission electron microscopy and related techniques are applied to the investigation of various defects in semiconductors induced by local segregation during crystal growth, device fabrication process, and operation of devices. Structure and nature of defects in heavily doped liquid phase epitaxial crystals of GaAlAs/GaAs, InGaAsP/InP, and InGaAsP/GaAs are investigated and compared in terms of point defect reaction during crystal growth. Composition-modulated structures are observed in InGaAsP crystals due to spinodal decomposition of the crystal during the growth process. Intrinsic gettering centers in oxygen-free silicon crystals during standard three step annealing process are identified. The gettering centers correspond to butterfly-type defect complexes consisting of dislocation loops and microprecipitates. Supersaturation of silicon interstitials is resposible for this process. Defect structures in gradually degraded GaAlAs and InGaAsP/InP double-heterostructure light emitting diodes are investigated structurally and compared regarding recombination enhanced defect reaction during operation. In each study, it is particularly emphasized that these structural and compositional techniques are extremely effective for the identification of defects in semiconductor materials and devices induced by local segregation.
