Demonstration of Integrated AlScN Photonic Devices on 8-inch Silicon Substrate

In combination with higher piezoelectric effect and larger optical second-order susceptibility (χ ⁽²⁾ ) compared with aluminum nitride (AlN), scandium-doped aluminum nitride (AlScN) platform is considered as a new platform for future integrated photonics. Hence, further studies are necessary to unlock the potential of the AlScN photonic platform and achieve integrated photonic devices with better performance. In this work, we fabricated the highly c-axis-orientated and low-surface-roughness AlScN thin films by reactive magnetron sputtering with 9.6% and 20% Sc concentrations. Then, we fabricated essential photonic devices including directional coupler (DC), Mach-Zehnder interferometer (MZI), and micro-ring resonator (MRR) based on the AlScN photonic platform. The measured extinction ratios (ERs) of MZIs are 22 dB for A _l0.904 Sc _0.096 N and 24 dB for A _l0.8 Sc _0.2 N. The maximum quality (Q) factors of MRRs are 3.2×104 for A _l0.904 Sc _0.096 N and 2.2×10 ⁴ for Al0.8Sc0.2N, while the waveguide bending losses are about 6.1 dB/cm for A _l0.904 Sc _0.096 N and 10.1 dB/cm for A _l0.8 Sc _0.2 N, respectively. These results pave the way towards low-loss integrated AlScN photonic applications such as acousto-optic modulation, nonlinear optical generation.