Integration of Yttrium Iron Garnet Films via Reactive RF Sputtering Bethanie
- PDF / 356,434 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 49 Downloads / 172 Views
ABSTRACT This work aims to equip integrated optical circuits with important magneto-optical devices, such as isolators, that are currently available only as discrete components. Reactive rf sputtering was used to grow cerium-doped yttrium iron garnet films onto a variety of substrates, including SiO 2-buffered Si, fused Si0 2 and MgO. MgO was used because it has proven to be a good buffer material for semiconducting substrates. Ce-doping was not effective via reactive sputtering due to a scale which formed on the Ce metal that prevented sufficient contact with the rf target. The films were amorphous as deposited. Stoichiometric Y3Fe 5 0 12 fidms yielded smooth, polycrystalline garnet films upon annealing. A study of the effect of fluctuations in the Y:Fe ratio revealed that oxygen content is important for the prevention of secondary phases. Therefore, a high oxygen content should be used in the sputtering gas and subsequent annealing should be performed in oxygen. INTRODUCTION The motivation driving this work is the integration of magneto-optical materials with semiconductor platforms. Many important applications will benefit from this integration, including photonic integrated circuits (PICs) through nonreciprocal waveguide devices such as isolators, and high resolution magneto-optic screens through spatial light modulators. Currently the choice materials for commercial magneto-optical devices are iron garnets, such as yttrium iron garnet (YIG), that are grown by liquid phase epitaxy. This technique involves very high temperatures, but more importantly, it requires garnet substrates. Therefore, integration with semiconductor platforms is only possible through hybrid techniques, such as ion slicing [1] and thermal bonding [21. This work investigated a new fabrication technique, reactive rf sputtering, for growing iron garnets directly onto buffered semiconductor substrates. Sputtering produces more adherent, dense films than other vacuum phase techniques, and a variety of substrates can be used. The potential monolithic integration of magneto-optical components with semiconductor electro-optics promises to decrease the size, weight and cost, and increase the speed and reliability of photonic integrated circuits (PICs) and other advanced devices. Although other MO materials, such as dilute magnetic semiconductors and transition metal- and rare earth-doped rn[-V semiconductors, are easier to integrate with semiconductor platforms, YIG has orders of magnitude greater Faraday rotation. Sputtering can also be used to deposit oxide buffer layers onto semiconductor substrates to protect their surfaces from decomposition and chemical reactions during garnet deposition. These same buffer layers can act as claddings for integrated magneto-optical devices which will function as waveguides. This work focused on using a variety of substrates including themally oxidized Si, and Si0 2 and MgO which have proven successful as buffer layers for use with MOCVD-grown Ce:YIG films.[3] Future work will involve sputtering buffer layers o
Data Loading...
