Silicon‐Lattice‐Matched Boron‐Doped Gallium Phosphide: A Scalable Acousto‐Optic Platform

• Published in: Advanced materials (Weinheim) 2024-02, Vol.36 (5), p.e2305434-n/a
• Main Authors: Yama, Nicholas S., Chen, I‐Tung, Chakravarthi, Srivatsa, Li, Bingzhao, Pederson, Christian, Matthews, Bethany E., Spurgeon, Steven R., Perea, Daniel E., Wirth, Mark G., Sushko, Peter V., Li, Mo, Fu, Kai‐Mei C.
• Format: Article
• Language: English
• Subjects: Acoustic waves; acousto‐optics; Boron; Data processing; Energy gap; Figure of merit; gallium phosphide; Gallium phosphides; integrated photonics; Lattice matching; latticed‐matched; Optical resonators; Optics; Photonics; Refractivity; Silicon; Telecommunications; Wavelengths
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202305434

The compact size, scalability, and strongly confined fields in integrated photonic devices enable new functionalities in photonic networking and information processing, both classical and quantum. Gallium phosphide (GaP) is a promising material for active integrated photonics due to its high refractive index, wide bandgap, strong nonlinear properties, and large acousto‐optic figure of merit. This study demonstrates that silicon‐lattice‐matched boron‐doped GaP (BGaP), grown at the 12‐inch wafer scale, provides similar functionalities as GaP. BGaP optical resonators exhibit intrinsic quality factors exceeding 25,000 and 200,000 at visible and telecom wavelengths, respectively. It further demonstrates the electromechanical generation of low‐loss acoustic waves and an integrated acousto‐optic (AO) modulator. High‐resolution spatial and compositional mapping, combined with ab initio calculations, indicate two candidates for the excess optical loss in the visible band: the silicon‐GaP interface and boron dimers. These results demonstrate the promise of the BGaP material platform for the development of scalable AO technologies at telecom and provide potential pathways toward higher performance at shorter wavelengths. This study implements the first integrated photonic and acousto‐optic devices in novel thin‐film boron‐doped gallium phosphide, indicating its potential as a highly scalable hybrid photonics platform for integration with color centers in high‐index materials. Optical, acoustic, and materials characterization is performed, revealing both strong intrinsic properties and clear pathways toward improvement.