Instability of Amorphous Oxide Semiconductors via Carrier-Mediated Structural Transition between Disorder and Peroxide State

2011/12/21 by Nahm, Ho-Hyun, Kim, Yong-Sung, Kim, Dae Hwan
#Disordered Systems and Neural Networks (cond-mat.dis-nn) #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci)

paper · doi:10.48550/arxiv.1112.4914

Abstract

The excited holes occupying the valence band tail states in amorphous oxide semiconductors are found to induce formation of meta-stable O₂^2- peroxide defects. The valence band tail states are at least partly characterized by the O-O ppσ* molecular orbital, and the localized-hole-mediated lattice instability results in the formation of the peroxide defects. Along with the O-O bond formation, the ppσ* state is heightened up into the conduction bands, and two electrons are accordingly doped in the electronic ground state. The energy barrier from the O₂^2- peroxide state to the normal disorder state is found to be 0.97 eV in hybrid density functional theory. The hole-mediated formation of the meta-stable peroxide defects and their meta-stability is suggested as an origin of the negative bias and/or illumination stress instability in amorphous oxide semiconductors.

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