The effect of nitrogen on self-assembled GaInNAs quantum dots grown on GaAs

We investigate the effect of nitrogen on self-assembled GaInNAs quantum dots (QDs) grown on GaAs (001) substrates by gas-source molecular beam epitaxy. The dot density of GaInNAs QDs decreases with increasing nitrogen. The reduced strain resulted from nitrogen incorporation decreases dot density of QDs. However, we find that the dot density of Ga0.3In0.7N0.02As0.98 QDs is still significantly lower than that of Ga0.41In0.6As QDs, even though they have comparable nominal strain. This difference can be explained by the composition fluctuation in the wetting layer. The inhomogeneous local strain due to the composition fluctuation decreases the number of dots when the dots begin to form, resulting in lower dot density after QD growth. The dot density difference between GaInNAs QDs and GaInAs QDs becomes smaller with decreasing growth temperature. Therefore, the PL intensity of GaInNAs QDs grown at low temperature (450 degreesC) improved to be comparable to that of GaInAs QDs, while the PL intensity of the GaInNAs QDs grown at high temperature (520 degreesC) dramatically decreased with increasing nitrogen composition. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.