Relation between Al vacancies and deep emission bands in AlN epitaxial films grown by NH3-source molecular beam epitaxy

Abstract

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Near-midgap deep levels in Al0.26Ga0.74N grown by metal-organic chemical vapor deposition

“…In particular, V Al -oxygen defects have been considered to be the most possible origin for a deep-level-related luminescence observed in AlN. 6,7 It was also pointed out that those defects can act as dominant recombination centers. Further investigation is needed to clarify the origin of nearmidgap levels in AlGaN detected by DLTS, correlating with optically observed emission spectra.…”

“…3 Although photoluminescence ͑PL͒ or cathodoluminescence ͑CL͒ investigation has shown some characteristic luminescence peaks related to deep electronic levels in AlGaN and AlN, [3][4][5][6][7] electrical characterization on deep levels in AlGaN or AlGaN/GaN heterostructure has been reported only a few times. [8][9][10][11] In particular, the deep-level transient spectroscopy ͑DLTS͒ method only detected deep levels with activation energies under 0.9 eV, 10 in spite of the fact that a near-midgap level can act as a dominant recombination center rather than a level near conduction or valence band.…”

“…Thus, the present study indicates that the AlGaN layer includes, at least, a nearmidgap level with an energy range between 1.5 and 2.3 eV from the bottom of the conduction band. Several groups have reported deep-level peaks in PL and CL spectra for AlGaN and AlN, [3][4][5][6][7] which are related to complex defects based on the III-column vacancies ͑V Al and V Ga ͒. In particular, V Al -oxygen defects have been considered to be the most possible origin for a deep-level-related luminescence observed in AlN.…”

Characterization of a freestanding AlN substrate prepared by hydride vapor phase epitaxy

“…Broad luminescence bands related to deep levels were observed at around 3.4, 4.1 and 4.5 eV in both PL spectra. These bands are thought to originate from Al vacancies (V Al ) and oxygen complexes (V Al -O), V Al and Si complexes (V Al -Si), and V Al , respectively, on the basis of a comparison of these peak positions with those reported in the literature [14,15] , respectively. Thus, it is thought that the Si impurities in the freestanding AlN substrate were caused by the Si starting substrate.…”

Low temperature growth of c-axis oriented AlN films on γ-LiAlO2 by radio frequency magnetron sputtering

“…[3][4][5]. AlN films can be grown on sapphire by metal organic chemical vapor deposition [6,7] or molecular beam epitaxy [8][9][10] at high growth temperature. The crystalline quality of AlN films is deteriorated by threading dislocations which usually originate from the large lattice mismatch and * Corresponding author.…”