We have studied structural changes that occur during annealing of GaInNAs/GaAs multiple quantum wells grown by metalorganic vapor-phase epitaxy (MOVPE). Different thermal treatments led to an improved room-temperature photoluminescence (PL) intensity, but also to room-temperature PL peak splitting. This splitting is related to the appearance of compositional clustering as displayed by transmission electron microscopy (TEM). In addition to this, interfacial layers on each side of the wells have also been observed by TEM and their composition is discussed on the basis of high resolution x-ray diffraction studies. It is suggested that the interface layers are indium deficient, but enriched in nitrogen, degrading the optical quantum well performance and indicating a need for improved switching sequences in the MOVPE growth.

We have investigated the structure and optical properties of GaAs0.97N0.03/GaAs produced by metalorganic vapor phase epitaxy grown on GaAs surface at 520–550 °C. Using cross-sectional transmission electron microscopy and photoluminescence spectroscopy (PL), we show the presence of a 5–6-nm-thick nitrogen-rich interfacial region. The nitrogen composition near the interface is twice higher (x=0.038) than that of the bulk epilayer (x=0.016). PL data shows two peaks located at 1.05 and 1.18 eV associated to the interfacial region and the bulk layer, respectively. We discuss several mechanisms of surface enrichment of nitrogen that occurred during the first stage of GaAsN growth.

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