Wavelength and polarization variations of InAs/GaAs quantum dots emission at liquid Helium temperature via microphotoluminescence spectroscopy

Abstract

In this paper, we investigate variation of the wavelength, intensity and polarization of the self-assembled InAs/GaAs quantum dots emission by microphotoluminescence spectroscopy at the liquid helium temperature. The microcavity wafer sample is grown by molecular beam epitaxy (MBE) and chemically etched into the micropillar structure (with elliptical cross section - long and short axis 2µm×1.5µm respectively). Two polarized modes of the micropillar and also quantum dot in the orthogonal axis of long and short diameters are considered and marked by H and V respectively. The analysis of the spectra shows that by increasing temperature, the quantum dot emission wavelength will be shifted towards longer wavelength, and at resonance wavelength of quantum dot and cavity confined modes which are red shifted less than quantum dot, enhancement would happen. Changes in emission wavelength and coupling of four individual quantum nanoparticles in the sample (with different spatial and spectral conditions) were studied in the temperature range ~ 5-50 K. Also, experiments show that the polarization amount and fine structure splitting for different quantum dots are different. The difference can be attributed to the deviations from the symmetric shape of quantum dots and the capping stage during next epitaxial growth. Polarization variability on- and off- resonance by changing temperature is also reported.