Thin Patterned Lithium Niobate Films by Parallel Additive Capillary Stamping of Aqueous Precursor Solutions

Abstract

Thin micropatterned lithium niobate (LiNbO3) layers may be used for photonic components, actuators, and data storage devices because LiNbO3 exhibits nonlinear optical properties as well as anisotropic polarizability and ferroelectric behavior. Commonly, thin micropatterned LiNbO3 layers are integrated into device architectures by complex manufacturing algorithms including direct wafer bonding, mechanochemical wafer thinning or mechanical cleavage of thin LiNbO3 layers from bulk LiNbO3 crystals, as well as lithographic pattering of and/or pattern transfer into the thin LiNbO3 layers. The high-throughput generation of thin microstructured LiNbO3 layers by parallel additive capillary stamping of environmentally friendly aqueous LiNbO3 precursor solutions with topographically patterned porous polymer stamps is reported. The precursor solutions contain the cheap, commercially available compounds lithium acetate and niobium oxalate hydrate, which are simply dissolved in water as received. In this way, rough surfaces not suitable for layer transfer methods involving direct wafer bonding, such as the surfaces of indium tin oxide (ITO) substrates, are functionalized with microstructured LiNbO3 layers. Microstructured holey 100 nm-thick LiNbO3 films showing uniform second-harmonic generation (SHG) except at the positions of the holes are obtained. Orthogonal substrate formation is demonstrated by electrodeposition of gold into the holes, which increases the SHG output 5.4 times.