title: Photoinduced dehydrogenation of defects in undoped a-si:H using positron annihilation spectroscopy.
abstract: We report changes in variable-energy positron annihilation spectroscopy measurements on undoped hydrogenated amorphous silicon films after light soaking. The change, seen predominantly in the high momentum band of the annihilation radiation, is not reversed by thermal annealing. We suggest, following recent models of the Staebler-Wronski effect, that light exposure induces hydrogen trapped in vacancylike defects to become mobile in the Si network. The observations place constraints on models of hydrogen motion fitting macroscopic Staebler-Wronski effect kinetics and may help to achieve a definitive description of metastability in a-Si:H.
authors.affiliation: Department of Electronic Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
authors.forename: X
authors.initials: X
authors.lastname: Zou
authors.forename: Y C
authors.initials: YC
authors.lastname: Chan
authors.forename: D P
authors.initials: DP
authors.lastname: Webb
authors.forename: Y W
authors.initials: YW
authors.lastname: Lam
authors.forename: Y F
authors.initials: YF
authors.lastname: Hu
authors.forename: C D
authors.initials: CD
authors.lastname: Beling
authors.forename: S
authors.initials: S
authors.lastname: Fung
authors.forename: H M
authors.initials: HM
authors.lastname: Weng