Electric field instabilities in TlGaSe2 crystals

Current–Voltage (I–V) characteristics of TlGaSe2 single crystals have been measured in the direction perpendicular to the layers plane in the temperature region of 80 K–300 K. Samples were placed between two micas and electrical contacts were placed on the surfaces of micas (so called “contactless” measurements). Applied electric field was varied from −1000 V/cm to +1000 V/cm. Current oscillations have been observed only in the temperature region, 145 K–190 K. It is shown that these oscillations are the result of low frequency (∼0.01 Hz) oscillations of current with time which are due to electric field instabilities occurring within the crystals. The model is discussed for such field instabilities based on the inhomogeneous crystalline structure of the investigated crystals.

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