Improvement on Thermal Stability of Nano-Domains in Lithium Niobate Thin Films

Abstract

We present a simple and effective way to improve the thermal stability of nano-domains written with an atomic force microscope (AFM)-tip voltage in a lithium niobate film on insulator (LNOI). We show that nano-domains in LNOI (whether in the form of stripe domains or dot domains) degraded, or even disappeared, after a post-poling thermal annealing treatment at a temperature on the order of ∼100 ∘ C. We experimentally confirmed that the thermal stability of nano-domains in LNOI is greatly improved if a pre-heat treatment is carried out for LNOI before the nano-domains are written. This thermal stability improvement of nano-domains is mainly attributed to the generation of a compensating space charge field parallel to the spontaneous polarization of written nano-domains during the pre-heat treatment process.

Recent Progress in Lithium Niobate

“…In paper [8] it was confirmed that the nano-domains in lithium niobate thin films are thermally unstable even at a temperature of the order of~100 • C, which can be easily reached due to light absorption. The thermal instability of nano-domains could be very detrimental to practical applications, such as periodically poled lithium niobate (PPLN) microcavities, PPLN ridge waveguides, and ferroelectric domain memories.…”

Evolution of Nanodomains and Formation of Self-Organized Structures during Local Switching in X-Cut LNOI

“…Nowadays, SPM is successfully used in LNOI wafers to create domain structures and domain imaging using piezoelectric force microscopy (PFM) [32][33][34][35][36][37]. Investigations have primarily been performed on Z-cut LNOI.…”

Domain structure formation by local switching in the ion sliced lithium niobate thin films

“…[15][16][17] The thermal stability of the created domains after the preheat treatment has been shown recently. 20 The domain imaging at the cross section of LNOI by scanning transmission electron microscopy revealed the much stronger domain wall inclination, 21 compared to bulk LN crystals. 22,23 The further decrease in PPLN periods and increase in the domain pattern stability need the deeper study of the domain growth during local switching in LNOI wafers.…”

“…15 The domain growth and interaction during local switching of LNOI wafers have been studied by piezoresponse force microscopy (PFM). [15][16][17][18][19][20] Formation of the stable isolated domains with charged domain walls (CDWs) and the absence of domain interaction have been found in LNOI wafers with a metal electrode under the LN film. [15][16][17] The thermal stability of the created domains after the preheat treatment has been shown recently.…”