Bistability and Metastability of the Gallium Vacancy in GaAs: The Actuator of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>EL</mml:mi></mml:math>2?

Abstract

We have used the Green's-function technique to carry out electronic-structure and total-energy calculations for the gallium vacancy in GaAs and for the nearest-neighbor (arsenic vacancy)-(arsenic antisite) pair which results when an adjacent arsenic atom hops over and fills the gallium vacancy. The results are interpolated with a tight-binding model for intermediate positions of the moving arsenic atom. The system shows bistability and metastability, and seems to describe many properties of the $\mathrm{EL}$ 2 center.