[12p-A202-1~13] 13.1 Fundamental properties, surface and interface, and simulations of Si related materials

▼ [12p-A202-7] Atomic structures and electrical properties of SiO₂/4H-SiC interfaces

〇(DC)Efi Dwi Indari^1,2, Yoshiyuki Yamashita^1,2, Ryu Hasunuma³, Kikuo Yamabe³ (1.Kyushu University, 2.NIMS, 3.University of Tsukuba)

Keywords:EXAFS, interface structure, SiO2/4H-SiC

We investigated the relationships between atomic structures and electrical properties of SiO₂/4H-SiC interfaces with different crystal orientations of the substrate and thermal oxidation procedures using extended x-ray absorption fine structure (EXAFS) and electrical methods. From EXAFS oscillations, we found the C and Si vacancies formation at the SiC substrate side of SiO₂/4H-SiC (0001) and SiO₂/4H-SiC (000-1) interfaces, respectively. Compressive stresses at the SiC substrate side of SiO₂/4H-SiC (0001) and SiO₂/4H-SiC (000-1) interfaces with the dry thermal oxidation procedure were indicated from reduction of bond lengths in EXAFS. Comparing previous studies with the present study, wet oxidation exhibited less interface stress than dry oxidation. We also found interface stress relaxation by wet oxidation was more effective for 4H-SiC (000-1) substrates than for 4H-SiC (0001) substrates. Relationships between the interfacial atomic structure with the electrical properties were found as follows. A high interface stress related to a high total-density of interface states, while a high interface charge related to a high gate leakage current onset and a high breakdown electric field.