Red-Shift and Improvement of Photoluminescence Characteristics by Incorporation of Nitrogen in In(Ga)As/GaAs Quantum Dots

It is observed that the incorporation of nitrogen in In(Ga)As quantum dots during the metal-organic chemical vapor deposition has an effect of shifting the photoluminescence to longer wave-lengths. The nitrogen supplied in the form of dimethylhydrazine in an amount as low as 2.7 % of that of AsH₃ during the growth of InAs and InGaAs quantum dots (QD) results in the QDs emitting at 1300 nm that is about 100 nm shift to longer wavelength from that of the InAs QDs grown under the same conditions without nitrogen. In addition, the FWHM of the room temperature PL peak of InAsN/GaAs QDs is measured to be 33 meV as compared to -65 nm measured from the InAs/GaAs and InGaAs/GaAs QDs. The grown InAsN/GaAs quantum dots keep the integrated intensity of the PL peak at room temperature to 8 % of that at 10 K. The carrier decay time at room temperature is measured to be similar to that at 10 K with a value of 600 ps. All these characteristics are in contrast to those from InAs/GaAs and InGaAs/GaAs QDs grown without nitrogen. We believe that the narrow PL peak width, the large PL yields and the long carrier decay time at room temperature indicate that the nitrogen has an effect of reducing the size distribution of the QDs and the grown InAsN/GaAs QDs are of high crystal quality.