Origins of unintentional incorporation of gallium in InAlN layers during epitaxial growth, part II: Effects of underlying layers and growth chamber conditions

Validity of Vegard’s rule for Al1−xInxN (0.08 < x < 0.28) thin films grown on GaN templates

“…These results are consistent with several studies in the literature reporting parasitic Ga-incorporation in Al 1−x In x N layers where the exact Ga-profiles will depend on the history of previous growth runs in the reactor [35,[55][56][57][58][59][60]. InN content derived from XRD using Vegard's rule [27] or the modified Vegard's rule described by equation (1) [30] as a function of the InN content measured by RBS for sample series C (a), S (b) and T (c).…”

“…Possibly such anomalous behaviour can also be explained by hydrostatic strain introduced by defects or by impurities. In particular, Ga contamination features in the literature on MOCVD growth of Al 1-x In x N films [35,[55][56][57][58][59][60].…”

MOVPE grown periodic AlN/BAlN heterostructure with high boron content

“…The Al signal intensity decreases when boron signal intensity increases during BAlN growth, which indicates that boron atoms substitute Al atoms on the III sites of lattice to form BAlN alloy. 5-period AlN/BAlN layers exhibit good uniformity except that the first AlN layer has lower AlN intensity which is due to some Ga contamination from the sample holder and reactor [15]. It should be pointed out that the boron signal cannot be zero when it is sputtered into AlN layer considering the SIMS detection limit when thin layers are analyzed.…”

Determination of Ga auto-incorporation in nominal InAlN epilayers grown by MOCVD

“…InAlN layers and other III-nitride materials are commonly prepared by metalorganic chemical vapour deposition (MOCVD) where group III precursors, typically trimethylalkyls, react with NH3 in carefully controlled conditions on a substrate surface, such as sapphire, silicon carbide or silicon. Recently it has been reported that unintentional Ga incorporation [5,6] in InAlN layers can occur during MOCVD growth, potentially attributed to ¬¬¬left-over Ga precursor residue from previous growth on the reactor walls/susceptor [5,7,8] and the decomposition of preceding Ga-containing layers [5,9]. Each proposed reason has convincing arguments, particularly when the geometry of the reactor and the use of Ga in the preparation of buffer or device layers prior to the InAlN growth are considered.…”