Monolithic Integration of ScAlN Modulators on Silicon‐On‐Insulator Platform

ABSTRACT Monolithic integration of functional materials with the conventional silicon‐on‐insulator (SOI) platform is a key strategy for expanding the applications of silicon photonics. Among various emerging materials, ferroelectric scandium‐doped aluminum nitride (ScAlN) has gained significant attention because of its second‐order optical nonlinearity, electro‐optic (EO) property, CMOS fabrication compatibility, and flexible material control via Sc doping concentration. However, achieving high‐performance and scalable devices through monolithic integration requires a system architecture that leverages both the maturity of silicon processing and the favorable material properties of ScAlN. Here, we demonstrate a 200 mm wafer‐scale monolithic integration of Sc 0.1 Al 0.9 N EO modulator on the SOI platform with a top‐down electrode design enabling a large electric field, which directly accesses the diagonal EO component ( r 33 ). A multilayer electrode configuration is employed to enhance the RF‐optical field overlap, yielding an enhanced modulation efficiency. Our results establish a versatile and robust testbed for early‐stage material research, enabling reliable evaluation and integration of emerging materials despite immature fabrication processes.