Reliability study of the band gap of rare earth oxides measured by XPS Spectra

Er2O3,Tm2O3 and Yb2O3 films were deposited on Si (100) and quartz substrates by radio frequency magnetron technique. The energy gaps of the films were measured by X-ray photoelectron spectroscopy (XPS) and optical methods. The energy gaps of Er2O3,Tm2O3 and Yb2O3 are found to be 6.3 +/- 0.1,5.8 +/- 0.1 and 7.1 +/- 0.1 eV by optical measurements. For XPS measurements, the energy gaps of the films are 6.2 +/- 0.2,6.0 +/- 0.2 and 6.9 +/- 0.2 eV, respectively. The results show that using XPS to measure the energy gap of rare earth metal oxide film is feasible in an allowable deviation.