Low threshold current operation of 1.3 μm GaInNAs/GaAs laser diodes

We report on the results of low threshold 1.3 μm GaInNAs laser diodes grown with solid source MBE using an RF-coupled plasma source to generate reactive nitrogen from N₂. Growth can be performed much like that of InGaAs under the usual As-stable conditions, however, suitable growth conditions for incorporating nitrogen with a sticking coefficient near unity and achieving brightest and narrowest PL spectra require growth temperatures below 520°C. Under these conditions, N completely displaces As and the N content is determined by the N flux. In contrast to MOCVD there is no major mutual influence between the incorporation of N and In, making the growth process relatively simple. In addition, careful optimisation of indium and nitrogen content, QW thickness and barrier composition are essential to achieve the highest active material quality. Because GaInNAs/GaAs MQWs are quite susceptible to thermal annealing, special care has been devoted to the evaluation of suitable in-situ annealing conditions. Based on these optimisations laser structures have been realised and characterised as broad area lasers with stripe width of 100 μm. The use of GaAsN barriers gives the lowest threshold current densities, however, this appears to be accompanied by a trade-off in the T₀ value. Also our data show the generally observed trend of higher thresholds for longer emission wavelengths