Structure and motion of basal dislocations in silicon carbide

Abstract

$30\ifmmode^\circ\else\textdegree\fi{}$ and $90\ifmmode^\circ\else\textdegree\fi{}$ Shockley partial dislocations lying in ${111}$ and basal planes of cubic and hexagonal silicon carbide, respectively, are investigated theoretically. Density-functional-based tight-binding total-energy calculations are used to determine the core structure and energetics of the dislocations. In a second step their electronic structure is investigated using a pseudopotential method with a Gaussian basis set. Finally, the thermal activation barriers to glide motion of $30\ifmmode^\circ\else\textdegree\fi{}$ and $90\ifmmode^\circ\else\textdegree\fi{}$ Shockley partials are calculated in terms of a process involving the formation and migration of kinks along the dislocation line. The mechanism for enhanced dislocation movement observed under current injection conditions in bipolar silicon carbide devices is discussed.