Influence of low temperatures and thermal annealing on the optical properties of InGaPAs quantum dots

The results of the study of the optical properties of low-density InGaPAs quantum dots, as well as the effect of low temperatures and thermal annealing parameters on their optical and structural properties were presented. InGaPAs quantum dots were formed by substituting phosphorus with arsenic in InGaP layer directly during epitaxial growth. The optical properties of InGaPAs quantum dots were studied by photoluminescence (PL) spectroscopy. Photoluminescence spectra at liquid nitrogen temperature (–196 °С) made it possible to determine the features of nonradiative recombination in heterostructures. The heterostructures were subjected to short-term thermal annealing at temperatures of 600 and 650 °C for 2 min to estimate the effect of annealing on the optical and structural properties of quantum dots. It was shown that at –196 °С the contribution of nonradiative recombination can be considered insignificant for the entire measured range of pumping power rage but at temperatures above –73 °С, the contribution of nonradiative Shockley- Reed recombination can be observed. Rapid thermal annealing of InGaPAs quantum dots led to reduce the number of point defects and growth of PL intensity. InGaPAs quantum dots and substitution method can find their application in the creation of single photon sources. The presented experimental results should be considered for implementing such sources, especially for optimizing the width and intensity of the radiation line.