Silicon-Based Highly c‑Axis-Oriented Strontium Barium Niobate Films with Large Pockels Coefficients.

To develop a new generation of high-performance silicon-based electro-optic modulators, it is necessary to find an electro-optic crystal with a simple fabrication process, stable chemical properties, and large Pockels coefficients, such as strontium barium niobate (Sr x Ba1-x Nb2O6, SBN). In this work, potassium-doped Sr0.75Ba0.25Nb2O6 and sodium-doped Sr0.75Ba0.25Nb2O6 buffers were fabricated on SiO2 via the sol-gel method, followed by the deposition of Sr0.75Ba0.25Nb2O6 (SBN75) films using radio frequency magnetron sputtering (RFMS). This sequential processing enabled the realization of SBN75 films exhibiting a c-axis preferential orientation. Lattice mismatch is not a limiting factor in this approach. Furthermore, the extracted Pockels coefficient r 33 of highly c-axis-oriented SBN75 films reached a maximum value of 431.3 pm/V, which is 10 times larger than that in lithium niobate (LN). The aforementioned findings make SBN75 a promising candidate for compact and high-speed electro-optic modulators.