ON THE INFLUENCE OF NITROGEN ON THE INDIUM INCORPORATION IN InGaAsN EPILAYERS

InGaAsN alloys have attracted much interest in the last few years for their potential applications in otical fiber communication devices operating at 1.3 and 1.55 microns. Incorporation of N in InGaAs yields quantum wells that exhibit the desired infrared emission in the optical windows of silica fibers and, at the same time, reduces the lattice mismatch relative to GaAs. The band gap and the strain can be independently tuned by changing the In and the N content, so that accurate control the In and the N content in the alloy is of fundamental importance. Metal-organic chemical vapor phase deposition (MOCVD) and molecular beam epitaxy (MBE) can be used to grow InGaAsN on GaAs substrates and laser diodes based on the quaternary alloy have been demonstrated. MBE has been extensively used to grow InGaAs layers and the protocols for growing the ternary alloy in a large range of In content are well established and accurate. Nitrogen is incorporated into the ternary alloy, to obtain the InGaAsN, by producing in the MBE growth chamber a plasma containing nitrogen. Here we present transmission electron microscopy (TEM) evidence of the influence of nitrogen on indium incorporation into the quaternary alloy. Our results indicate that incorporation of In in the material is reduced by up to 20% relative to ternary alloy grown in the same conditions for N concentrations near 4.5%. Lower nitrogen concentrations lead to smaller changes in the indium incorporation rate.