High Luminescence Efficiency from GaAsN Layers Grown by MBE with RF Nitrogen Plasma Source

Abstract

(In)GaAsN based heterostructures have been found to be promising candidates for the active region of 1.3 micron VCSELs. However, (In)GaAsN bulk layers and quantum wells usually demonstrate lower photoluminescence intensity than their nitrogen-free analogues. Defects associated with lower temperature growth and N-related defects due to plasma cell operation and possible nonuniform distribution of nitrogen enhance the non-radiative recombination in N-contained layers. We studied the photoluminescence intensity of GaAsN layers as a function of N content in MBE grown samples using rf-plasma source. Increasing the growth temperature to as high as 520 °C in combination with the increase in the growth rate allowed us to avoid any N-related defects up to 1.5% of nitrogen. Low-temperature-growth defects can be removed by post-growth annealing. We achieved the same radiative efficiency of GaAsN samples grown at 520 "C with that of reference layer of GaAs grown at 600 "C. Compositional fluctuations in GaAsN layers lead to characteristic S-shape of temperature dependence of photoluminescence peak position and this feature is the more pronounced the higher the amount of nitrogen in GaAsN. Annealing reduces compositional fluctuations in addition to the increase in the photoluminescence intensity. The results obtained are important for further improving the characteristics of InGaAsN lasers emitting at 1.3 micron.

High Temperature Growth of the Dilute Nitride GaAsN using a Nitrogen ECR Plasma Source

“…The optimum growth temperature for MBE grown GaAs is around 600ºC and it is expected that the optimum growth temperature for the dilute nitride GaAsN, containing no more than a few percent nitrogen, will be similar. However the use of RF plasmas as sources of active nitrogen has suffered from the fact that at growth temperatures above about 500ºC there is a dramatic reduction in obtainable nitrogen concentrations [1], [2], [3], [4], [5], [6], [7]. This has meant that GaAsN layers have had to be grown at temperatures around 480ºC and the as-grown layer quality has been poor as a result.…”