Study on electrical defects level in single layer two-dimensional Ta₂O₅

Two-dimensional atomic-layered material is a recent research focus, and single layer Ta₂O₅ used as gate dielectric in field-effect transistors is obtained via assemblies of Ta₂O₅ nanosheets. However, the electrical performance is seriously affected by electronic defects existing in Ta₂O₅. Therefore, spectroscopic ellipsometry is used to calculate the transition energies and corresponding probabilities for two different charged oxygen vacancies, whose existence is revealed by x-ray photoelectron spectroscopy analysis. Spectroscopic ellipsometry fitting also calculates the thickness of single layer Ta₂O₅, exhibiting good agreement with atomic force microscopy measurement. Nondestructive and noncontact spectroscopic ellipsometry is appropriate for detecting the electrical defects level of single layer Ta₂O₅.