Papers by Keyword: Defect Passivation

Abstract: Al2O3 deposition and subsequent post-deposition annealing (Al2O3-PDA) is proposed as an effective method to passivate electrically active defects in Ge-rich SiGe-on-insulator (SGOI) substrates. We found that Al2O3-PDA could not only suppress the surface reaction during Al-PDA, but could also effectively reduce the defect-induced acceptor and hole concentration in Ge-rich SGOI. Al2O3-PDA greatly improves the electrical characteristics of a back-gate metal-oxide-semiconductor field-effect transistor fabricated on Ge-rich SGOI.

Abstract: We propose a treatment of nitrogen radical irradiation to 4H-SiC surfaces for improving thermally grown SiO2/SiC interfaces. X-ray photoelectron spectroscopy (XPS) analyses revealed that a 1.7-nm-thick nitride film was formed by nitrogen radical exposure for 30 min and that Si-N bonds were retained after subsequent 10 min oxidation. It was also confirmed by secondary ion mass spectrometry (SIMS) that nitrogen atoms were piled up at the SiO2/SiC interface for the samples fabricated by thermal oxidation for 3 min with nitrogen plasma exposure. The metal-oxide-semiconductor (MOS) capacitors with a thin oxynitride layer formed by nitrogen radical exposure to the SiC surface and subsequent thermal oxidation exhibited excellent capacitance-voltage (C-V) characteristics. The interface state density (Dit) was significantly reduced by nitrogen radical exposure even at the shallow energy level near the conduction band edge. A minimum Dit value of 1.4 × 1011 cm-2eV-1 at Ec – E = 0.44 eV was achieved. Therefore, we can conclude that the treatment of nitrogen radical irradiation to the SiC surface prior to thermal oxidation is a promising method for improving SiC-MOS characteristics.

Abstract: We propose a treatment combining nitrogen plasma exposure and forming gas annealing (FGA) to improve the electrical properties of SiO2/SiC interfaces. Although conventional FGA at 450°C alone is not effective for reducing interface traps and fixed charges, our combination treatment effectively reduces both even at moderate temperatures. We achieved further improvement by applying our treatment at higher (over 900°C) FGA temperatures, including lower interface state density (Dit) values for both deep and shallow energy levels (1 - 4 x 1011 cm-2eV-1). Considering that nitrogen incorporation promotes hydrogen passivation of interface defects, a possible mechanism for the improved electrical properties is that interface nitridation eliminates carbon clusters or Si-O-C bonds, which leads to the formation of simple Si and C dangling bonds that can be readily terminated by hydrogen. We therefore believe that our treatment is a promising method for improving the performance of SiC-based MOS devices.