Determination of the Absolute Thickness of Ultrathin Al2O3 Overlayers on Si (100) Substrate

The thickness of nanometer Al2O3 films was studied by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The thickness was determined from mutual calibration of the XPS and TEM measurements. The thickness offset of Al2O3 films was proved to be close to zero by in situ XPS analysis. The thicknesses of a series of Al2O3/Si (100) films with different Al2O3 thicknesses could be determined by mutual calibration from the thicknesses measured by TEM and XPS. The electron attenuation length of the Al 2p electron was determined as 2.4334 nm in the Al2O3 matrix.