Analysis on interface states of ultrathin-SiO rSi 111/

We analyzed the current–voltage I–V.characteristics of ultrathin SiO2rSi 111.and its relation with the surface step density. The oxides were grown on flat 08-off.and vicinal 0.58-off.substrates in dry O2 with variation of oxidation temperature and thickness, from 500–8008C and from 1.5–2.0 nm, respectively. The I–V curves indicated that the steps were preferable sites for the formation of interface states, when the oxides were grown at around 6008C. However, the correlation between the current and step density became smaller when the oxides were grown at lower or higher temperatures. We also found that the correlation was reduced as oxidation proceeded and the oxides became thicker. A model to explain the results was suggested by taking into account of the relaxation of oxide films around the steps and on terraces. q2000 Elsevier Science B.V. All rights reserved.