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

Abstract

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 (SrxBa1–xNb2O6, 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 r33 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.