Point Defect Trapping in Crystal Growth

Abstract

The possibility of trapping significant quantities of point defects during growth of a crystal is considered. Calculations are based on the well‐established theory of growth from the vapor on vicinal surfaces and the results are applied approximately to more complex cases. Concentrations of point defects, either above or below equilibrium, can be trapped under some conditions. In most cases the effect is insignificant. The crucial characteristic of a growth condition is defined by the dimensionless parameter D_v/Rd where D_v is the bulk diffusion coefficient for point defects (vacancies), R is the growth rate, and d is the ``effective thickness'' of the surface. The value of d is about 1 atom layer in most cases, but may be greater at solid‐melt interfaces. Large supersaturations of point defects may be trapped if D_v/Rd is small. For very large values of D_v/Rd, subsaturation concentrations of vacancies may be trapped. Growth trapping accounts for the loss of dislocations from metal whisker crystals during growth and may support a simple explanation of some substructure formation during solidification of pure single crystals.