Time tuning of ferroelectric film varactors under pulse voltages

Significant difference in the capacitance tunability of paraelectric state ferroelectric capacitors under dc and pulse voltages is demonstrated. Along with a fast tuning (tau < 10 ns) the slow relaxation processes (tau >= 100 s) responsible for up to similar to 30% variation of the capacitance were observed. The observed effect is a main obstacle for application of paraelectric state ferroelectrics on microwaves. (C) 2007 American Institute of Physics.