Low-Loss Higher-Order Cross-Sectional Lam\'e Mode SAW Devices in 10-20 GHz Range

TL;DR

This study investigates high-frequency surface acoustic wave (SAW) devices in the 10-20 GHz range, demonstrating that higher-order Lamé modes exhibit lower loss than Rayleigh modes, supporting their potential for frequency scaling.

Contribution

The paper introduces the fabrication and analysis of higher-order cross-sectional Lamé mode SAW devices with improved Q factors at high frequencies, advancing SAW technology for frequency scaling.

Findings

Higher-order Lamé modes have Q factors of 1000-3000.

Lamé modes show lower loss than Rayleigh modes at high frequencies.

SAW devices remain viable for frequency scaling with minimal loss increase.

Abstract

This paper presents surface acoustic wave (SAW) acoustic delay lines (ADL) for studying propagation loss mechanisms in Lithium Niobate (LN). Devices were fabricated by depositing 50 nm aluminum patterns on 600 nm X-Cut LN on amorphous silicon on silicon carbide, where longitudinally dominant SAW was targeted. Upon fabrication, higher-order thickness-based cross-sectional Lam\'e modes and Rayleigh modes were studied for their Q factors using acoustic delay lines. Utilizing bi-directional electrodes, ADL with lateral lambda values ranging from 0.4 um to 0.6 um were measured. Higher order Lame modes were found to have consistently higher Q factors than their Rayleigh mode counterpart, on the order of 1000-3000, showing high-frequency SAW devices as still viable candidates for frequency scaling without a substantial increase in loss.