Theoretical study of the hydrogen-saturated ideal silicon vacancy

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Abstract
The self-consistent pseudopotential method and supercell configuration are used to study the electronic structure of the hydrogen-saturated vacancy (HSV) in Si. A unified picture is obtained by comparing three systems: (i) bulk Si (no vacancy), (ii) the vacancy alone, and (iii) the HSV complex in which each Si dangling bond is compensated by H. The vacancy dangling-bond states are found to be removed from the gap and the H-H interactions do not interfere with the formation of a strong H-Si bond. The reappearance of the gap and the form of the charge density in the proximity of the HSV implies a stability which suggests this may be one of the strain-relieving configurations which occurs upon hydrogenation of amorphous silicon. These calculations also suggest a potentially observable acceptor state if a HSV-like defect can be created in crystalline silicon.