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Title: Microstructure from joint analysis of experimental data and ab initio interactions: Hydrogenated amorphous silicon

A study of the formation of voids and molecular hydrogen in hydrogenated amorphous silicon is presented based upon a hybrid approach that involves inversion of experimental nuclear magnetic resonance data in conjunction with ab initio total-energy relaxations in an augmented solution space. The novelty of this approach is that the voids and molecular hydrogen appear naturally in the model networks unlike conventional approaches, where voids are created artificially by removing silicon atoms from the networks. Two representative models with 16 and 18 at. % of hydrogen are studied in this work. The result shows that the microstructure of the a-Si:H network consists of several microvoids and few molecular hydrogen for concentration above 15 at. % H. The microvoids are highly irregular in shape and size, and have a linear dimension of 5–7 Å. The internal surface of a microvoid is found to be decorated with 4–9 hydrogen atoms in the form of monohydride Si–H configurations as observed in nuclear magnetic resonance experiments. The microstructure consists of (0.9–1.4)% hydrogen molecules of total hydrogen in the networks. These observations are consistent with the outcome of infrared spectroscopy, nuclear magnetic resonance, and calorimetry experiments.
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. Department of Physics and Astronomy, The University of Southern Mississippi, Hattiesburg, MS 39406 (United States)
  2. (United States)
  3. Department of Physics and Astronomy, Condensed Matter and Surface Science Program, Ohio University, Ohio 45701 (United States)
  4. Department of Physics, The University of Texas, Arlington, Texas 76019 (United States)
Publication Date:
OSTI Identifier:
22399172
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 24; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION SPECTROSCOPY; ATOMS; CALORIMETRY; CONCENTRATION RATIO; HYDROGEN; HYDROGENATION; INFRARED SPECTRA; MICROSTRUCTURE; MOLECULES; NUCLEAR MAGNETIC RESONANCE; RELAXATION; SILICON; SURFACES; VOIDS