Electronic origin of the conductivity imbalance between covalent and ionic amorphous semiconductors

Hui Xiong Deng, Su Huai Wei, Shu Shen Li, Jingbo Li, Aron Walsh

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Amorphous semiconductors are known to give rise to greatly reduced conductivity relative to their crystalline counterparts, which makes the recent development of amorphous oxide semiconductors with high electron mobility unexpected. Using first-principles molecular dynamics and electronic structure simulations, we have analyzed the electronic and optical properties of covalent and ionic oxide amorphous semiconductors. We observe that in covalent systems, amorphization introduces deep defect states inside the gap, resulting in a substantial deterioration of electrical conductivity. In contrast, in ionic systems, such as the transparent conducting oxide ZnO, amorphization does not create deep carrier-recombination centers, so the oxides still exhibit good conductivity and visible transparency relative to the crystalline phases. The origin of the conductivity imbalance between covalent and ionic amorphous semiconductors can be explained using a band coupling mechanism.

Original languageEnglish
Article number125203
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume87
Issue number12
DOIs
Publication statusPublished - 2013 Mar 21

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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