Light-induced metastability in pure and hydrogenated amorphous silicon D. R. Queen, X. Liu, J. Karel, Q. Wang, R. S. Crandall, T. H. Metcalf and F. Hellman EPL, 112 2 (2015) 26001 Published online: 05 November 2015 DOI: 10.1209/0295-5075/112/26001