Formation of $Ga$ interstitials in $(Al,In)yGa1−yNxP1−x$ alloys and their role in carrier recombination

Formation of complex defects involving a $Ga$ interstitial $(Gai)$ in $(Al,In)yGa1−yNxP1−x$ alloys and their effects on optical quality are studied by photoluminescence (PL) and optically detected magnetic resonance spectroscopies. Introduction of these defects is shown to be largely promoted by incorporation of N. In quaternary alloys, concentrations of the defects are found to critically depend on the group III atoms that replace $Ga$⁠, i.e., it is largely enhanced by the presence of $Al$ in alloys, but is only marginally affected by In incorporation. The effect is attributed to differences in surface adatom mobilities of the group III atoms involved and their bonding strength with $N$⁠. The revealed $Gai$ complexes are shown to act as efficient nonradiative recombination centers degrading the PL efficiency. The defects exhibit high thermal stability and can only be partially removed by postgrowth rapid thermal annealing.