Photoconductive properties of Bi_4Ti_3O_(12)/Si heterostructures with different thickness of the Bi_4Ti_3O_(12) film

摘要

Ferroelectric Bi_4Ti_3O_(12)(BiT) thin films of different thicknesses were deposited on p-type Si substrates using the Chemical Solution Deposition (CSD) method. The films were crystallized by the conventional thermal annealing for 30 min at temperatures in the 500-700 deg C range. It was found that the shape of the photoconductive signal spectral distribution is dependent on the film thickness. For thin films (150 nm) four peaks were observed (400, 500, 860 and 1075 nm) and the photoconductive signal occurs only if the Si substrate is negatively biased. For thicker films (500 nm) only two peaks were observed (370 and 1075 nm) and the photoconductive signal occurs no matter the polarity of the applied voltage.