Charge effects controlling the current hysteresis and negative differential resistance in periodic nanodimensional structures Si/CaF2

A kinetic model for charge carrier transport in periodic nanodimensional Si/CaF2 structures via localized states in the insulator was suggested. The appearance of the built-in electric charge in the insulator due to the polarization of the charge trapped by localized charge centers and the subsequent discharge of these centers were investigated. It was demonstrated that these phenomena explain the hysteresis of current-voltage (I-V) characteristics with a change of polarity of the applied external voltage. These phenomena bring about the portion of negative differential resistance (NDR) in these characteristics. Major factors ensuring the NDR appearance for the structures under investigation are the charge carrier density at the contacts and the charge voltage. At temperatures below 250 K, the NDR portion disappears. It was demonstrated that, in the course of recording the experimental I-V characteristics, the effect of the charging-discharging of localized centers should decrease. This decrease is in accordance with an increase in the time interval of measuring the current at a constant voltage and with an increase in the step of the applied voltage. This effect actually disappears for the measurement time of 20 s and the voltage step of 0.6 V. (C) 2002 MAIK "Nauka / Interperiodica".