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 Al
_0.904
Sc
_0.096
N and 24 dB for Al
_0.8
Sc
_0.2
N. The maximum quality (
Q
) factors of MRRs are 3.2×10
⁴
for Al
_0.904
Sc
_0.096
N and 2.2×10
⁴
for Al
_0.8
Sc
_0.2
N, while the waveguide bending losses are about 6.1 dB/cm for Al
_0.904
Sc
_0.096
N and 10.1 dB/cm for Al
_0.8
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.