Electrically Controllable Plasmonic Waveguide Based On A Metal-Insulator-Semiconductor(MIS) Structure

Surface plasmon polaritions(SPP)has been recognized as an important approach for manipulating light within nanoscale due to its special optical properties.But in the applications of SPP,the trade-off between energy confinemet and propagation loss is still exist,and the properties of metal materials are still hard to control.According to these two problems,We propose to use an N-type metal-insulator-semiconductor(MIS)structure composed of Ag/Zr O2/Si to build up electron density near the surface of the heavily doped Silicon layer,in an effort to realize negative real permittivity in the communication window around 1.55 ?m.Then we analyze the controllable plasmonic waveguide based on this MIS Structure.The main contents of this paper as follows:(1)Based on quantum mechanical model of an accumulated MIS capacitor,we analysis the accumulation of electrons in MIS structure.Then we obtain the distribution of complex permittivity in electronic accumulation area by Drude model.Simulation shows that,the electron density near the surface of the doped semiconductor can be increased by 2~3 orders of magnitude and negative near the surface of the doped semiconductor is possible when gate voltage is high enough.(2)The electromagnetic mode and its localization properties in electronic accumulation area and the whole MIS structure are studied.Mode analysis shows that a slot-like leaky mode or an epsilon-near-zero(ENZ)mode can be found in electronic accumulation area,they can hybridize with the conventional mode SPP mode at metal-insulator(M-I)interface.The hybrid mode shows relatively low loss and controllable nanoscale localization properties.(3)The effective index and extinction coefficient of the hybrid SPP mode in MIS structure are analyzed.Based on the results obtained,we propose a silicon-based modulator of micron size.Simulation shows that,this device can realize pure intensity Modulation and the modulation efficiency is up to 2.3 dB/?m.