Nondestructive imaging and characterization of ferroelectric domains in periodically poled crystals

Abstract

We report the nondestructive investigation and visualization of periodically poled domains in ferroelectric potassium titanyl phosphate (KTP) crystals using polarization sensitive scanning force microscopy (SFM). Applying an alternating voltage technique to SFM allows ferroelectric domain wall resolution beyond 100 nm. Image contrast between KTP and Rb doped KTP, i.e., rubidium titanyl phosphate (RTP) regions arises from the differential piezoelectric response. We find the polarization vectors in both KTP and RTP to be aligned parallel to the negative z axes as deduced (a) when comparing our data with a ferroelectric reference sample, i.e., tri-glycine sulfate (b) from comparison of nanoscale hysteresis loops recorded on KTP and RTP, and (c) from direct domain switching in KTP applying very high electric fields between tip and counter electrode. The latter experiments show that nanoscale ferroelectric domains in KTP switch from the negative to the positive z-axes alignment for electric fields stronger than 750 V/cm. Nevertheless, spontaneous backswitching is observed after a couple of minutes.

Imaging mechanism of piezoresponse force microscopy of ferroelectric surfaces

“…The presence of the electrostatic forces hypothesis is also supported by observations of nonpiezoelectric surfaces. 32 In contrast, the existence of a lateral PFM signal [33][34][35] and the absence of relaxation behavior in PFM contrast as opposed to SSPM contrast, 36,25 as well as numerous observations using both EFM-SSPM and PFM, 37,38 clearly point to a significant electromechanical contribution to PFM contrast. In order to resolve the controversy regarding the origins of PFM contrast, we analyze the contrast formation mechanism and relative magnitudes of electrostatic versus electromechanical contributions to PFM interactions for the model case of c ϩ , c Ϫ domains in tetragonal perovskite ferroelectrics.…”

Piezoresponse force spectroscopy of ferroelectric-semiconductor materials

“…This approach was later used by several groups to probe crystallographic orientation and microstructure effects on switching behavior. [36][37][38][39][40][41] Recently, PFM spectroscopy has been extended to an imaging mode using an algorithm for fast ͑100-300 ms͒ hysteresis loop measurements developed by Jesse et al 42 The progress in experimental studies has stimulated a parallel development of theoretical models to relate PFM hysteresis loop parameters and materials properties. A number of such models are based on the interpretation of phenomenological characteristics of PFS hysteresis loops similar to macroscopic P-E loops, such as slope, imprint bias, coercive bias, remanent response, and work of switching, 43,44 as illustrated in Fig.…”

Three-dimensional high-resolution reconstruction of polarization in ferroelectric capacitors by piezoresponse force microscopy

“…Vertical PFM ͑VPFM͒ and lateral PFM ͑LPFM͒ imaging methods, used to detect out-of-plane and in-plane polarization components, respectively, have been described in detail elsewhere. [5][6][7][11][12][13][14][15][16][17][18] The modulation voltage ͑typically 0.6 Vrms at 10 kHz͒ was applied to the top electrode of the capacitor using a conduca͒ Author to whom correspondence should be addressed; electronic mail: alexei -gruverman@ncsu.edu tive PFM tip, which was also used to detect the piezoelectric response of the capacitor. Commercially available Pt-coated Si rectangular cantilevers ͑1.0-2.6 N/m force constant͒ have been used in this study.…”