The effects of point defects in AlxGa1−xN (x = 0 to 0.33) films with similar threading dislocation densities were investigated. The epitaxial layers were grown under conditions applicable to laser-diode quantum wells, barriers and waveguide layers. The evolution of deep level defect energy and density were quantitatively tracked versus x using deep level optical spectroscopy. Three defect levels were observed, whose defect density increased with x. The energy level of a defect suspected to be related to the group-III vacancy appeared to track the vacuum level, and a near-valence band defect level deepened with respect to the valence band maximum.

The Influence of Al Composition on Point Defect Incorporation in AlGaN. T.A.Henry, A.Armstrong, A.A.Allerman, M.H.Crawford: Applied Physics Letters, 2012, 100[4], 043509