BaTiO₃ (BTO) is a highly promising material for the fabrication of electro-optic (EO) modulators due to the large effective Pockels coefficient of the material, particularly in an epitaxial form. It also has the added benefit of being readily integrated on a Si material platform via a SrTiO₃ template. These two characteristics make epitaxial BTO ideal for use in next generation silicon photonics applications. Being a ferroelectric, BTO has a unique crystallographic direction in which the ferroelectric polarization points. For EO modulators, because the polarization direction controls the coupling between light and an external electric field, it is important to understand how different growth methods and subsequent processing affect the direction of the ferroelectric polarization. Certain electro-optic devices may require polarization to be in the plane of the film (in-plane switching liquid crystal devices), while other applications may require it to be normal to the plane of the film (Mach–Zehnder modulator). Here, we review the growth of epitaxial BTO on Si by a variety of deposition methods including molecular beam epitaxy, pulsed laser deposition, and RF sputtering. We summarize the resulting BTO film structure and quality based on the reported characterization results. We also discuss EO measurements of basic devices made from this material platform where such data are available.

中文翻译：

---

BaTiO3在Si上的外延集成用于电光应用

BaTiO ₃（BTO）是一种用于制造电光（EO）调制器的极有前途的材料，因为该材料的有效普克尔系数很大，尤其是外延形式。它还具有通过SrTiO ₃易于集成在Si材料平台上的附加优势。模板。这两个特性使外延BTO成为下一代硅光子学应用的理想选择。作为铁电体，BTO具有铁电极化指向的独特晶体学方向。对于EO调制器，由于偏振方向控制着光与外部电场之间的耦合，因此了解不同的生长方法和后续工艺如何影响铁电偏振方向非常重要。某些电光设备可能要求偏振在薄膜的平面内（平面内切换液晶设备），而其他应用可能要求偏振在薄膜的平面上（马赫曾德尔调制器）。在这里，我们通过各种沉积方法（包括分子束外延，脉冲激光沉积和RF溅射。我们根据报告的表征结果总结了最终的BTO膜结构和质量。我们还将讨论从该材料平台（可得到此类数据）制造的基本设备的EO测量。