Ferroelectric domain inversion and its stability in lithium niobate thin film on insulator with different thicknesses

TL;DR

This study experimentally characterizes ferroelectric domain inversion and stability in lithium niobate thin films of varying thicknesses, providing insights for their use in nonlinear and electro-optic devices.

Contribution

It compares domain inversion and stability in lithium niobate films of different thicknesses, including submicron and micron scales, using novel imaging and evaluation methods.

Findings

Micron thick samples show stable domains for at least a month.

Submicron films achieve large-area domain inversion with a lifetime of 25 hours.

Different mechanisms may influence domain stability depending on film thickness.

Abstract

Ferroelectric domain inversion and its effect on the stability of lithium niobate thin films on insulator (LNOI) are experimentally characterized. Two sets of specimens with different thicknesses varying from submicron to microns are selected. For micron thick samples (~28 um), domain structures are achieved by pulsed electric field poling with electrodes patterned via photolithography. No domain structure deterioration has been observed for a month as inspected using polarizing optical microscopy and etching. As for submicron (540 nm) films, large-area domain inversion is realized by scanning a biased conductive tip in a piezoelectric force microscope. A graphic processing method is taken to evaluate the domain retention. A domain life time of 25.0 h is obtained and possible mechanisms are discussed. Our study gives a direct reference for domain structure-related applications of LNOI, including guiding wave nonlinear frequency conversion, nonlinear wavefront tailoring, electro-optic modulation, and piezoelectric devices.