Electron-Spin-Resonance And Electrically Detected-Magnetic-Resonance Characterization On P-Bc Center In Various 4h-Sic(0001)/Sio2 Interfaces

We characterized an intrinsic interface defect, called the "P-bC center," formed at 4H-SiC(0001)/SiO2 interfaces by means of electron-spin-resonance (ESR) and electrically detected-magnetic-resonance (EDMR) spectroscopies. The formation of the P-bC center was observed with a spin density of 3-4x10(12) cm(-2) after standard thermal oxidation. This center could be effectively removed by the NO post-oxidation-anneal (POA) process or ultra-high-temperature oxidation and could be passivated by H atoms via the H-2 POA process. There was a clear correlation between the P-bC center and field-effect mobility (mu(FE)) of 4H-SiC(0001) metal-oxide-semiconductor field effect transistors (MOSFETs). The P-bC center decreased mu(FE) because this center acts as electron traps, reducing the free-carrier density in the inversion channel of 4H-SiC(0001) MOSFET. We also examined the counter doping effect of NO POA by introducing N-15 impurities; however, the counter doping of N-15 donors was not detectable by ESR (much lower than 2x10(11)cm(-2)). Highly sensitive EDMR measurements revealed that the P-bC center has two isotropic hyperfine (HF) interactions at 1.3 and 6.8mT and suggested that its main C-13 HF interaction should be larger than 14mT. Based on the present experimental data, the origin of the P-bC center was ascribed as a carbon-related interface defect that forms a C-H bond after hydrogen passivation. This feature is similar to that of the porous-P-bC centers (carbon dangling-bond centers) found in porous-SiC/SiO2 systems. However, their HF signatures indicated that the P-bC center at 4H-SiC(0001)/SiO2 interfaces and the porous-P-bC centers in porous-SiC should be different centers associated with different wave functions.