Published online by Cambridge University Press: 21 February 2011
We present experimental evidence for an enhancement in hydrogen diffusivity in a-Si:H with hydrogen concentration. The concentration dependence is attributed to the saturation of the density of hydrogen traps consisting of Si-H bonds with increasing hydrogen concentration. As a consequence, hydrogen lifetime in mobile interstitial and/or bond-center sites is enhanced. The saturation occurs when the rate of trap filling by hydrogen injection from the plasma exceeds the rate of trap creation.