Designs of Silicon MIS Phase Modulator With a Deposited AlN Film as the Gate Dielectric

We propose and analyze a silicon metal-insulator- semiconductor phase modulator based on a poly-Si/AlN/Si horizontal slot waveguide. The AlN gate dielectric exhibits an inherent Pockels effect, which can provide additional phase modulation besides that provided by the free-carrier plasma dispersion effect of Si. The proposed modulator with an optimized geometry offers a high modulation efficiency of 0.95 V · cm for the 1.55-μm transverse magnetic light even the electrooptical coefficient of AlN (r 33 ) is only 1 pm/V, which is ~40% better than the SiO 2 counterpart with the same equivalent oxide thickness. The modulation efficiency increases quickly with r 33 increasing, reaching 0.2 V · cm when r 33 is 10 pm/V.