The effect of SrTiO3 substrate orientation on the surface morphology and ferroelectric properties of pulsed laser deposited NaNbO3 films

Orientated NaNbO3 (NN) films were grown on SrRuO3/(001)SrTiO3 [SRO/(001)STO], SRO/(110)STO, and SRO/(111)STO substrates by pulsed laser deposition. Scanning electron microscopy images showed that the surface morphologies of the NN/SRO/(001)STO, NN/SRO/(110)STO, and NN/SRO/(111)STO took the form of a stepped structure, a striped pattern, and trigonal pyramidal-like structures, respectively. The dielectric and ferroelectric properties of the films were characterized. The NN/SRO/(110)STO film showed the lowest relative dielectric constant and the largest remanent polarization of 30.8 μC/cm2 among all films. These were interpreted as being due to the orientation direction of the NN film grown on (110)STO being parallel to the polarization direction of NN.