Epitaxial yttrium iron garnet film for fabrication of high frequency on-chip inductors

The application of epitaxial yttrium iron garnet (YIG) thin film on high frequency on-chip spiral inductors is investigated. The YIG thin film with the thickness of 3.6 μ m was grown on GGG(111) substrate using the liquid phase method, which exhibits relatively high saturation magnetization 4πM s of 1615 Oe close to the bulk value of 1750 Oe and low initial coercivity H c of 0.5 Oe that minimizes the hysteretic losses. Subsequently, the spiral inductors were directly fabricated on the YIG/GGG(111) substrate. The results show substantial improvement in the optimum operating frequency and self-resonance frequency of the on-chip spiral inductor with the YIG thin film with an increase of 50% up to ∼7.5 GHz and 14.2 GHz, respectively, implying that on-chip spiral inductors with the YIG thin film can be applied to much higher frequency RF circuits.