Characterization of local piezoelectric behavior of ferroelectric GeTe and Ge2Sb2Te5 thin films

We studied the ferroelectric properties of GeTe and Ge2Sb2Te5 thin films through the analysis of capacitance-temperature, contact resonance piezoresponse force, resonance tracking piezoresponse force, and switching piezoresponse force microscopy measurements. These alloys are non-typical ferroelectric materials with low electrical resistivity, which makes their ferroelectric properties difficult to investigate by other conventional techniques. On the basis of measurement values of the Curie temperature, ferroelectric domain structure, piezoelectric coefficient d33, and coercive voltage were obtained. For the first time, hysteresis loops, and switching effects of domains under electrical field were observed in chalcogenide materials.