Valence band offsets at zinc-blende heterointerfaces with misfit dislocations: A first-principles study

Abstract

The electronic states induced by misfit dislocations at zincblende CdTe/CdS, CdS/ZnS, and InP/GaP heterointerfaces and their impacts on the valence band offsets are investigated using first-principles calculations. The (100) and (110) heterointerfaces including perfect edge dislocations with a Burgers vector of $\frac{a}{2}[1\overline{1}0]$ and a line vector of [001] are considered for each system. Two types of dislocation core structures are found: The ``closed'' core has four-membered rings only and contains threefold and fivefold coordinated cations, whereas the ``open'' core has ten-membered rings that involve threefold coordinated atoms. The closed core forms at the (110) interfaces and is energetically more favorable than the open core. The characteristics of dislocation-induced electronic states are heavily dependent on the system and core structure, but all have localized states in the valence and conduction bands. The localized states in the valence band mostly have anion-orbital characteristics, whereas those in the conduction band mainly have cation-orbital characteristics. Some, but not all, dislocation cores also induce electronic states in the gap between the higher of the valence band maxima and the lower of the conduction band minima in the two phases that constitute the interface. The explicit treatment of misfit dislocations changes the valence band offset between the regions at a distance of \ensuremath{\sim}1 nm or more from the heterointerface by typically \ensuremath{\sim}0.1 eV.