International Journal of Hydrogen Energy, Vol.38, No.14, 5974-5982, 2013
Interstitial hydrogen in ZnO and BeZnO
First principles calculations show that for both ZnO and BeZnO phases, H prefers the positive charge state and would bring about n-type conductivity as a donor, while H-0 and H- are energetically unfavorable with positive heat of formation. Calculation also reveals that H+ would probably occupy both bond-centered and anti-bonding sites due to a big migration barrier of site diffusion, which could therefore give a reasonable explanation to the experimental controversy regarding the location of H+ in the literature. Interestingly, the addition of Be could increase the stability and migration barrier of H+ in ZnO, and such an effect would be attributed to a stronger chemical bonding around the H atom formed in BeZnO. In addition, it is found that all the H+, H-0, and H- states would bring about a decrease of the band gap of ZnO and BeZnO due to the splitting of degenerate bands and leftward moving of energy bands. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.