High-EO + ferroelectric variant of AlN
Physics / mechanism
ScAlN replaces some Al atoms in AlN with Sc, dramatically increasing piezoelectric coefficient (5-10×) and electro-optic coefficient (~5×) versus pure AlN. At Sc fractions above ~30%, ScAlN becomes ferroelectric — which means non-volatile state storage in addition to active modulation. CMOS-fab compatible (Sc sputtering is established).
The killer pitch: ScAlN promises to be an EO material with both BTO-class strength AND CMOS-fab compatibility, sidestepping the integration headache that has slowed BTO. If reproducible at 200/300mm wafer scale, it’s a serious challenger.
Competitive landscape
Research stage. Active groups: Stanford (Brongersma), IBM Zurich, Fraunhofer IAF, Wisconsin (Wang). Several ScAlN-FET + ScAlN-FeMEM publications since 2023 indicate the same materials cross-pollination as photonics — ferroelectric memory researchers and ScAlN-photonic researchers overlap heavily.
Frontier (open questions)
See frontmatter frontier: block.