Effect of the top electrode on local piezoelectric and the ferroelectric response of PVDF thin films in PVDF/Au/Si and Ag/PVDF/Au/Si multilayers

The effect of the top Ag electrode on local piezoelectric and the ferroelectric response of PVDF thin films in PVDF/Au/Si and Ag/PVDF/Au/Si multilayers is probed using dual AC resonance tracking piezo force microscopy (DART-PFM). The 4 wt% PVDF thin films are prepared on Au/Si using a spin coater and the top electrode Ag is deposited with the DC magnetron sputtering method. The structural and microstructural characteristics are analyzed using a Raman spectrometer, grazing incidence X-ray diffraction, scanning electron microscopy with electron dispersive spectroscopy, and atomic force microscopy. The local piezoelectric and ferroelectric characteristics are found to be dependent upon the presence or absence of the top Ag electrode. Both the device structures display typical bi-stable ferroelectric and piezoelectric switching. The resultant non-uniform electric field due to the absence of a top electrode shows ferroelectric switching at an applied voltages ≥ ± 20 V compared to the low-voltage (down to ± 5 V) switching on Ag/PVDF/Au junctions. Furthermore, a higher d33 coefficient recorded in Ag/PVDF/Au is discussed with uniform electric field distribution in the devices. Our study reveals a clear dependency of local piezoelectric and ferroelectric characteristics upon the top electrode and its local domain switching phenomena. Graphical abstract