Localized deep levels in AlxGa1-xN epitaxial films with various Al compositions

By using high-temperature deep-level transient spectroscopy(HT-DLTS) and other electrical measurement techniques,localized deep levels in n-type AlxGa1-xN epitaxial films with various Al compositions(x = 0, 0.14, 0.24, 0.33, and 0.43)have been investigated. It is found that there are three distinct deep levels in AlxGa1-xN films, whose level position with respect to the conduction band increases as Al composition increases. The dominant defect level with the activation energy deeper than 1.0 eV below the conduction band closely follows the Fermi level stabilization energy, indicating that its origin may be related to the defect complex, including the anti-site defects and divacancies in AlxGa1-xN films.