Paper Title
Novel Double Oxide Layers MgO/Tio2 on Si MOS capacitor with high dielectric constant

Abstract
The double oxide layers MgO/TiO2/Si MOS capacitor was fabricated by liquid phase deposition method (LPD) in this study. It has been known that the band gap of titanium oxide (TiO2) is relatively small (~3.2 eV) in high dielectric constant materials. The energy band offset of TiO2with metal is quite small due to its small energy band gap, and Schottky emission mechanism in dielectric oxides from that electrons cross the dielectric oxide. Therefore, the magnesium oxide (MgO) with a relatively large band gap (~7.8 eV) and the high Schottky barrier height (Φb) was stacked on the TiO2 to improve this leakage current drawback. In this study, the Schottky emission and Fowler-Nordheim tunneling plots were utilized to extract the Φb. It was found that the Φb of the double layer is 0.56 eV. Theoretically, the Φb of MgO with metal aluminum (Al) was supposed to be 2.4 eV, and the Φb which is extracted in this study is much lower than that due to the traps and image force effect. As the negative bias was applied on the gate, MgO with high Φb effectively blocks the electrons from the gate to semiconductor, and the leakage current density is significantly decreased from 16.49 to 0.02 A/cm2 at -5 V. However, the effective dielectric constant was reduced from 24 to 16.5 with the stack of the MgO layer due to the series capacitors. Besides, the other electrical properties of double oxide layer MOS capacitor such as flat band voltage (Vfb), effective oxide charge density (Neff), hysteresis loop (ΔVfb), hysteresis oxide charge density (Notm), series resistance(Rs) and, interface trap density (Dit) were investigated, and they are -1.3 V, 3.6×1011 cm-2, -0.6 V, 4.5×1011cm-2, 1003Ω, and 2.32×1012 eV-1cm-2, respectively. Keywords - MOS, TIO2, Mgo, LPD, Double Oxide Layers, Electrical Characteristics, Leakage Current