Electret states and current oscillations in the ferroelectric semiconductor TlGaSe2

Low-frequency current oscillations (LFCOs) have been observed for the first time in the ferroelectric semiconductor TlGaSe2. It is shown that LFCOs can be observed in specially undoped high-resistivity single crystals and in crystals after annealing for some hours within the incommensurate phase. LFCOs are shown to be due to non-linear current–voltage (I–V) characteristics of the crystals. The origin of the non-linearity of the I–V characteristics is based on the formation of electret states due to the capture of carriers by deep impurity centres. The possible influence of electret states on the peculiarities of different physical properties observed in these crystals is discussed. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)