01, 0.1, and 1. Figure 7 HF and QS C – V curves for Al/SiO x N y /Si MOS capacitors (after annealing) utilizing SiO x N y layers. The layers were prepared under N2/O2 gas flow ratios of 0.01, 0.1, and 1. Conclusions SiO x N y films with a low nitrogen concentration (approximately 4%) have been prepared on n-type (001) Si wafers at 400°C for 9 min by oxidation-nitridation process in AP plasma using O2 and N2 diluted in He gas. Interface properties of SiO x N y films have been investigated

by C-V measurements, and it is found that addition of N into the oxide increases both the values of D it and Q f. After FGA, D it at midgap decreases from 2.3 × 1012 to 6.1 × 1011 cm−2 eV−1 with decreasing N2/O2 flow ratio from 1 to 0.01, buy SN-38 while the decrease of Q f is insignificant from 1.5 × 1012 to 1.2 × 1012

cm−2. These results suggest that a low N2/O2 flow ratio is a key parameter to achieve a low D it and relatively high Q f, which is useful to realize an effective field-effect find more passivation of n-type Si surfaces. Acknowledgements This work was supported in part by Grants-in-Aid for Scientific Research (no. 21656039, no. 22246017, and Global COE Program (H08)) from the Ministry of Education, Culture, Sports, Science and Technology, Japan. The authors would like to thank A. Takeuchi of Osaka University for his technical assistance. References 1. Dupuis J, Fourmond E, Lelievre JF, Ballutaud D, Lemiti M: Impact of PECVD SiON stoichiometry and post-annealing on the silicon surface passivation. Thin GW2580 Solid Films 2008, 516:6954–6958.CrossRef 2. Seiffe J, Gautero L, Hofmann M, Rentsch J, Preu R, Weber S, Eichel RA: Surface passivation of crystalline silicon by plasma-enhanced chemical vapor deposition double layers of silicon-rich silicon oxynitride and Miconazole silicon nitride. J Appl Phys 2011, 109:034105.CrossRef 3. Hallam B, Tjahjono B, Wenham S: Effect of PECVD silicon oxynitride film composition on the surface passivation of silicon wafers. Sol Energy Mater Sol Cells 2012, 96:173–179.CrossRef 4. Gusev

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