Simultaneous measurement of the piezoelectric and dielectric response of nanoscale ferroelectric capacitors by an atomic force microscopy based approach

摘要

We present a sensitive method to simultaneously acquire the C(V) characteristics and piezoresponse of sub-micron size ferroelectric capacitors using an Atomic Force Microscope (AFM). Model Pt/(La_(0.5),Sr_(0.5))CoO_3/PbZr_(0.4)Ti_(0.6) O_3/(La_(0.5),Sr_(0.5))CoO_3/La:SrTiO_3/Si nanocapacitors were fabricated by focused ion beam milling from 100μm~2 down to 0.04 μm~2. With this AFM based capacitance measurement technique we show clear "double-humped" C(V) for all sizes with no significant change in the peak value of the ε_r down to capacitors with the smallest area of 0.04 μm~2. The smallest capacitance measured is only of the order a few femtofarads, demonstrating the high sensitivity of the technique. Simultaneously, the piezoelectric response is recorded for each measurement, thus the technique facilitates simultaneous piezoresponse and dielectric characterization of ferroelectric memory devices.