Quantitative assessment of Al-to-N bonding in dilute Al(0.33)Ga(0.67)As(1-y)N(y)

A quantitative assessment of the group III-nitrogen bonding in low N-content Al(0.33)Ga(0.67)As(1-y)N(y)with y<=0.04 has been performed, using vibrational mode Raman spectroscopy for the quantitative analysis of local bond formation in combination with energy dispersive x-ray analysis and secondary ion mass spectrometry for chemical analysis. Clear evidence is obtained for the preferential bonding of nitrogen to Al with one nitrogen atom being coordinated to, at the average, 3.4 Al neighbors. This strong preference for Al-to-N bond formation can be understood in terms of the much larger cohesive energy of the Al-N bond compared to the Ga-N chemical bond. In spite of this phase-separation-like formation of local Al-N complexes, the fundamental band gap and the E1/E1 + delta1 band gaps show a continuous low-energy and high-energy shift, respectively, upon the addition of nitrogen as already known from dilute GaAsN.