Search

A novel characterization method is proposed to extract the optical frequency field-effect mobility ( μ op , FE ) of transparent conductive oxide (TCO) materials by a tunable silicon microring resonator with a heterogeneously integrated titanium-doped indium oxide ( ITiO ) / SiO 2 / silicon metal–oxide–semiconductor (MOS) capacitor. By operating the microring in the accumulation mode, the quality factor and resonance wavelength shift are measured and subsequently used to derive the μ op , FE in the ultra-thin accumulation layer. Experimental results demonstrate that the μ op , FE of ITiO increases from 25.3 to 38.4 cm 2 ⋅ V − 1 ⋅ s − 1 with increasing gate voltages, which shows a similar trend as that at the electric frequency.

Transparent conductive oxides have attracted escalating research interest for integrated photonic devices and metasurfaces due to the extremely large electro-optic modulation of the refractive index by the free-carrier-induced plasma dispersion effect. In this paper, we have designed and fabricated a silicon microring resonator using an indium-tin oxide gate as the electric-tuning electrode. It achieved an ultralarge resonance wavelength tunability of 271 pm/V, which is obtained through the reduced width of the ring waveguide and a high-dielectric-constant HfO2 insulator. We demonstrated a broad resonance wavelength tuning range of over 2 nm with an ultrafast response time of less than 12 ns and near-zero static power consumption, which outperforms traditional thermal tuning.