Further insight into the growth temperature influence of 1.3 μm GaInNAs/GaAs QWs on their properties

The authors further investigate the influence of growth temperature (T_g) on GaInNAs QWs grown on GaAs. 7 nm-thick GaInNAs QWs were grown with T_g in the range 400-470°C. As a first result, transmission electron microscopy clearly showed that flat interfaces are obtained for T_g lower than 450°C. Beyond this temperature, the upper interface of the QW starts to undulate. Then the series of QWs was annealed at different temperatures. The PL emission of the QWs was blue-shifted and narrowed. However, it was noticed that these evolutions occurred at a lower annealing temperature (T_a) when a lower T_g was used for the growth. Even though the PL energies of the different as-grown QWs were the same, this observation tends to show that the nanotexture of the GaInNAs alloys depends on T_g in the range of temperatures investigated. The texture obtained at low T_g is more easily rearranged, by annealing, into a more stable configuration. This result is of practical importance for the growth of GaInNAs QW laser structures. By using the lowest T_g for the GaInNAs QWs, the AlGaAs cladding layer growth temperature (usually around 620°C) is high enough to optimise the QW quality by its annealing effect.