Bonding of nitrogen in dilute InAsN and high In-content GaInAsN

Dilute InAs(1-y)N(y) and high In-content Ga(1-x)In(x)As(1-y)N(y) layers with y lt = 0.012 and x gt= 0.92 were grown by rf-nitrogen plasma source molecular-beam epitaxy on InP substrates using a metamorphic GaInAs buffer layer. The bonding of nitrogen in these alloys was analyzed by Raman spectroscopy, showing that nitrogen is incorporated in dilute InAsN as isolated N(As) for a nitrogen content of y = 0.005; two additional nitrogen-related modes were found to appear at higher nitrogen contents (y=0.012), possibly due to the formation of higher-order di-nitrogen In-N complexes. The addition of a small amount of Ga to the InAsN ([Ga] lt = 8%) was found to lead to an almost complete change from pure In-N bonding to a preferential bonding of the substitutional nitrogen to at least one Ga neighbour. Further, the effect of nitrogen incorporation on the higher-lying E(ind 1) and E(ind 1) + delta(ind 1) interband transitions of InAsN has been studied by spectroscopic ellipsometry, revealing a high-energy shift of both interband transitions with increasing nitrogen content at a rate similar to that reported for dilute GaAsN.