Epitaxy and characterisation of dilute III-As1-yNy on GaAs and InP

Epitaxial growth and characterisation of Ga_1-xIn_xAs_1-yN_y films and quantum wells are presented. Starting with the epitaxy on GaAs, recent results on the local bonding of nitrogen in Ga_1-xIn_xAs_1-yN_y are reviewed, revealing that bonding of nitrogen is controlled by an interplay between bond cohesive energy and reduction of local strain. Thus, III-N bonding can be changed from Ga-N to In-N by post-growth thermal annealing. For high In-content Ga_1-xIn_xAs_1-yN_y on InP it is demonstrated that only small amounts of Ga are necessary to cause the bonding of the nitrogen atoms to at least one Ga neighbour. The epitaxy on InP substrates, equivalent to a drastic increase in indium content, allows an extension of optical transitions to longer wavelengths. The feasibility of high In-content Ga_1-xIn_xAs_1-yN_y pseudomorphic quantum wells on InP is shown. The deterioration of the photoluminescence properties with increasing nitrogen incorporation can be partially compensated by thermal annealing. Within the resolution limits of the secondary ion mass spectrometry experiments, no annealing-induced loss of nitrogen was observed. The indium-rich strained Ga_0.22In_0.78As_0.99N_0.01 quantum wells are shown to exhibit room-temperature photoluminescence at wavelengths up to 2.3 μm. Finally quantum well lasers emitting at wavelengths beyond 2 μm are demonstrated.