Student Member (Osaka Univ.) Takashi Sugino Member (Osaka Univ.) Chiharu Kimura Non-member (Osaka Univ.) Hidemitsu Aoki Non-member (Osaka Univ.) Hirofumi Kurimoto Non-member (Osaka Univ.) Kentaro Chikamatsu Non-member (Osaka Univ.) Keywords : gate insulator film, wide bandgap semiconductor, Al2O3, AlSiO A gate insulator film with a large bandgap and a high dielectric constant is required to achieve high performance power field effect transistor (FET) on wide bandgap semiconductors such as SiC and diamond. An Al 2 O 3 film on diamond has been reported earlier. The Al 2 O 3 film has wide bandgap (9eV) and a high dielectric constant (more than 12). The AlO film was deposited by RF sputtering, but the film wasn't stoichiometoric and has large leakage currentsWe attempted to study on the Si-doped AlO (AlSiO) film which has both large bandgap and a high dielectric constant. This paper describes the characteristics of AlSiO (aluminumsilicate) film with Si-MIS and SiC-MIS structure.An AlSiO film was deposited on a p-Si substrate by RF sputtering. The film thickness was 20~57 nm. Characteristics of the AlSiO films with various Si concentrations (0%-30%) were investigated by the I-V and C-V characteristics using MIS Au/AlSiO/p-Si structure and the phsical characteristics are studied by XPS spectra.From the result of I-V characteristics of the AlSiO film, leakage current density was suppressed by the Si doping as shown in Figure 1. The AlSiO (Si: 12%) film has the minimum current density among all samples. It is thought that the defect of the AlO were cmpensated by Si doped AlO.Next, C-V characteristics of the Au/AlSiO/p-Si MIS structure was observed as shown in Figure 2. An ideal C-V curve was drawn. Flat band voltage shift (∆V FB ) was evaluated from the ideal flat band voltage. It is observed that ∆V FB decreases with increasing the Si concentration in AlSiO as shown in Figure 3. The space charge was possibly suppressed because dangling bonds in the non-stoichiometoric AlO film decreased by Si doping.The optimized AlSiO film (Si:12%) was applied to the SiC-MIS structure. As shown in Figure 3, the leakage current level was suppressed by applying the AlSiO films.-2 -1 0 1 2
