MRS Meetings and Events

 

NM07.09.03 2022 MRS Fall Meeting

Two-Step Annealing and Diffusion-Driven Exfoliation of Cerium-Doped Terbium Iron Garnet on Silicon Substrates

When and Where

Dec 1, 2022
8:15am - 8:30am

Hynes, Level 2, Room 203

Presenter

Co-Author(s)

Pang-Hsiao Liu1,Karthik Srinivasan1,2

University of Minnesota Twin Cities1,Cornell University2

Abstract

Pang-Hsiao Liu1,Karthik Srinivasan1,2

University of Minnesota Twin Cities1,Cornell University2
Thin-film rare-earth iron garnets are very promising non-reciprocal materials for isolators or circulators in photonic devices due to large Faraday rotation and low optical absorption. However, integration of these garnets as thin films in photonic systems faces some challenges, including reduced magneto-optical properties due to poor crystallinity in as-deposited films and limited acceptable annealing of semiconductor devices. To solve these problems, cerium-doped terbium iron garnet (CeTbIG) thin films have been deposited on silicon wafers in this work by sputtering followed by various two-step annealing. During deposition, the Ce content was controlled using the bias voltage of the Ce-target for reproducible CeTbIG. A systematic study of annealing was conducted, involving a first low temperature anneal and a second crystallization treatment to determine when exfoliation will occur. Specifically, a 400<sup>o</sup>C anneal for 3 minutes followed by a set of high-temperature treatments (950<sup>o</sup>C for 30 seconds then 900<sup>o</sup>C for 5 minutes) shows excellent crystallinity without the formation of any undesired phases. This is an improvement compared to traditional single-temperature anneals. Also, the high-temperature sequence caused vacancy diffusion, leading to the formation of a gap just inside the CeTbIG thin film at the substrate interface. This gap enables easy exfoliation. By analysis of diffusivities of iron and rare-earth cations from strain rate-stress data, it was determined that the diffusion mechanism may be related to Nabarro-Herring (lattice diffusion) model. The saturation magnetization and Faraday rotation of the exfoliated CeTbIG film were measured and found comparable to those of the CeTbIG film on the silicon substrate. By applying the two-step annealing an optimized CeTbIG exfoliated films were obtained. These films were transferred onto commercially integrated Si-waveguides for characterization of the magneto-optical properties.

Keywords

Ce | magnetooptic | sputtering

Symposium Organizers

Jeehwan Kim, Massachusetts Institute of Technology
Sanghoon Bae, Washington University in Saint Louis
Deep Jariwala, University of Pennsylvania
Kyusang Lee, University of Virginia

Publishing Alliance

MRS publishes with Springer Nature