Morphological and optical characterization of self-assembled InAlGaAs/GaAs quantum dots

This experimental study reports the morphological and optical properties of self-organized quaternary InAlGaAs quantum dots (QDs) grown on GaAs substrates. Atomic force microscopy (AFM) revealed the presence of QDs and their geometry across the sample surface, while the optical properties were verified by photoluminescence (PL) spectroscopy. Temperature-dependent PL measurements were performed for a series of samples with different indium compositions. Unlike conventional quantum well materials, the change in PL peak positions in QD structures exhibits a non-monotonic exotic dependence on temperature. Our AFM data confirm a bimodal distribution of dot sizes as corroborated by calculated thermal activation energies. A rapid decrease in the PL signal at elevated temperatures suggests that thermionic emission and interface defects are the two dominant mechanisms of carrier escape and recombination in these QD structures. Such a quaternary QD-based active region is important for realizing next-generation diode lasers with an emission wavelength shorter than 1 mu m. Published under an exclusive license by AIP Publishing.

Automated summary

This experimental study investigates the morphology and optical properties of self-organized quaternary InAlGaAs quantum dots grown on GaAs substrates. Atomic force microscopy (AFM) is used to observe the presence and geometry of the quantum dots, while photoluminescence (PL) spectroscopy is used to verify their optical properties. The temperature-dependent PL measurements reveal a non-monotonic dependence of the peak positions on temperature, unlike conventional quantum well materials. The AFM data and calculated thermal activation energies confirm a bimodal distribution of dot sizes. The rapid decrease in the PL signal at elevated temperatures suggests that thermionic emission and interface defects are the dominant mechanisms of carrier escape and recombination in these quantum dot structures. This study highlights the importance of quaternary quantum dot-based active regions for the development of next-generation diode lasers with shorter emission wavelengths.