Non-steady-state photo-EMF in semi-insulating GaAs under frequency-modulated illumination M. Bryushinin, V. Kulikov, I. Sokolov, P. Delaye and G. Pauliat EPL, 105 6 (2014) 64003 Published online: 27 March 2014 DOI: 10.1209/0295-5075/105/64003