CHARACTERIZATION OF PHOTOREFRACTIVE STRONTIUM-BARIUM NIOBATE WITH NON-STEADY-STATE HOLOGRAPHIC PHOTOCURRENTS

Measurements of non-steady-state holographic photocurrents and convent ional modulated photocurrents are performed with a n-type photorefract ive strontium-barium niobate crystal at light wavelength of 532 nm. Th e effective charge carrier density and the photocarrier diffusion leng ths for two orthogonal directions in the crystal are deduced. A ratio of the photoelectron mobilities along the c and a axis of 2.4 is obtai ned. The dependence of the photocurrent signals on the modulation freq uency points to an essential contribution of shallow traps to the char ge transport. (C) 1998 Elsevier Science B.V.