Fundamentals and engineering of defects

Abstract

An overview of the important defect types, their origins and interactions during the bulk crystal growth from the melt and selected epitaxial processes is given. The equilibrium and nonequilibrium thermodynamics, kinetics and interaction principles are considered as driving forces of defect generation, incorporation and assembling. Results of modeling and practical in situ control are presented. Strong emphasis is given to semiconductor crystal growth since it is from this class of materials that most has been first learned, the resulting knowledge then having been applied to other classes of material. The treatment starts with melt-structure considerations and zero-dimensional defect types, i.e. native and extrinsic point defects. Their generation and incorporation mechanisms are discussed. Micro- and macro-segregation phenomena – striations and the effect of constitutional supercooling – are added. Dislocations and their patterning are discussed next. The role of high-temperature dislocation dynamics for collective interactions, like cell structuring and bunching, is specified. Additionally, some features of epitaxial dislocation kinetics and engineering are illustrated. Next the grain boundary formation mechanisms, such as dynamic polygonization and interface instabilities, are discussed. The interplay between facets, inhomogeneous dopant incorporations and twinning is shown. Finally, second phase precipitation and inclusion trapping are discussed. The importance of in situ stoichiometry control is underlined. Generally, selected measures of defect engineering are given at the end of each sub-chapter.