Periodic changes in interface state distribution in accordance with layer-by-layer oxidation on Si(100)

The interface state densities near the midgap were measured with the progre ss of oxidation of atomically flat Si(100) surface. It was found that the i nterface state distribution in Si bandgap changes periodically with the pro gress of oxidation. Namely, the interface state density near the midgap of Si decreases drastically at oxide film thickness where the surface roughnes s of oxide film takes its minimum value, while it does not decrease at oxid e film thickness where the surface roughness takes its maximum value. In or der to minimize interface state densities, the oxide film thickness should be precisely controlled to within an accuracy of 0.02 nm. (C) 2000 Publishe d by Elsevier Science B.V.