Comparison of Charge Injection in SiO2 and Si3N4 for Capacitive RF MEMS Switches
Charge injection behaviours in SiO2 and Si3N4 dielectric layers are systematically studied with a Metal-Insulator-Semiconductor (MIS) structure before and after applying a constant dc bias voltage. We found that both the polarity and magnitude of charge accumulation in Si3N4 depend on the biasing direction, while the polarity and magnitude of charge accumulation in SiO2 seems independent on the biasing direction. Charge injection from the Semiconductor to the Si3N4 always dominates over charge injection from the metal electrode to the Si3N4. Electrons accumulate in the Si3N4 when the metal electrode is positively biased, and holes accumulate in the Si3N4 when the metal electrode is negatively biased. The hole accumulation is much bigger than the electron accumulation under the same magnitude of bias voltage. However, independent on dc bias polarity, electrons injection in SiO2 always dominates the charge accumulation either the metal electrode is positively biased or negatively biased. The charge accumulation under negative bias voltage is only slightly different from that under positive bias voltage with same magnitude. Furthermore, the experiment results also show that charge injection level exponentially increases with the applied voltage both in SiO2 and Si3N4. Taking into account the roles of electrons and holes in the process of charge injection, the observed experiment results can be simply explained by the tunnelling barrier at each contact interface.
Gang Li Ulrik Hanke Xuyuan Chen
Vestfold University College, Faculty of Science and Engineering Postbox 2243, N3103 T(o)sberg, Norway
国际会议
上海
英文
986-989
2011-08-08（万方平台首次上网日期，不代表论文的发表时间）