New Type of Charged Defect in Amorphous Chalcogenides

2004/09/17 by S. I. Simdyankin, T. A. Niehaus, Thomas A. Niehaus +5 · 1 citation
Engineering · Materials Science · Physics and Astronomy · #Chalcogenide Semiconductor Thin Films #Crystal Structures and Properties #Phase-change materials and chalcogenides #cond-mat.dis-nn #cond-mat.mtrl-sci

paper · pdf · doi:10.1103/physrevlett.94.086401

published as Phys. Rev. Lett. 94, 086401 (2005) · 5 pages, 2 figures

arxiv created 2004/09/17 · openalex publication_date 2005/03/02 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30

Abstract

We report on density-functional-based tight-binding simulations of a series of amorphous arsenic sulfide models. In addition to the charged coordination defects previously proposed to exist in chalcogenide glasses, a novel defect pair, [As₄]^\ensuremath--[S₃]⁺, consisting of a fourfold coordinated arsenic site in a seesaw configuration and a threefold coordinated sulfur site in a near-planar trigonal configuration, was found in several models. The valence-alternation pairs [S₃]⁺-S₁^\ensuremath- are converted into [As₄]^\ensuremath--[S₃]⁺ pairs under HOMO-to-LUMO electronic excitation. This structural transformation is accompanied by a decrease in the size of the HOMO-LUMO band gap, which suggests that such transformations could contribute to photodarkening in these materials.

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