Diffusion impact on thermal stability in self-assembled bilayer InAs/GaAs quantum dots (QDs)

B. Tongbram; Navneet Sehara; Jashan Singhal; Debabrata Das; D. Prasad Panda; S. Chakrabarti

doi:10.1117/12.2211749

15 March 2016 Diffusion impact on thermal stability in self-assembled bilayer InAs/GaAs quantum dots (QDs)

B. Tongbram, Navneet Sehara, Jashan Singhal, Debabrata Das, D. Prasad Panda, S. Chakrabarti

Proceedings Volume 9758, Quantum Dots and Nanostructures: Growth, Characterization, and Modeling XIII; 97580T (2016) https://doi.org/10.1117/12.2211749
Event: SPIE OPTO, 2016, San Francisco, California, United States

Abstract

The thermal stability of InAs/GaAs bilayer quantum dots structure has been investigated by photoluminescence (PL) measurements. The fabricated structure on thermal annealing PL shows no shift in peaks upto 650°C indicating a robustness till a certain temperature making it a suitable candidate for vertical cavity surface emitting lasers (VCSELs) and feedback lasers where ideally a fixed wavelength is required. Integrated Photoluminescence gave a high activation energy in the range of 200 meV for the ground state PL peak for all the coupled structures. Above 650°C there is a blue-shift in the PL peak. And at a very high temperature the dots start to diffuse into InAs wetting layer hence decreasing the quality of the crystal. The stability in the PL for temperatures below 650°C can be accounted by strain energy as it works against the interdiffusion of QD and the seed layer till a certain temperature hence it compensates for the temperature effect but after 650°C diffusion term becomes too strong and we observe a blue-shift in the peak. This can be justified theoretically by modifications in the Arrhenius diffusion equation. Due to this interdiffusion of In/Ga atom the dominance of the peak and the intensity of PL peak also changes as the QD composition changes [1-2]. Coupling the dots also leads to high activation energy which in-turn generates a stronger carrier confinement. But as the temperature increases, activation energy decreases weakening the carrier confinement potential because of interdiffusion between dot and seed layer.

Citation Download Citation

B. Tongbram, Navneet Sehara, Jashan Singhal, Debabrata Das, D. Prasad Panda, and S. Chakrabarti "Diffusion impact on thermal stability in self-assembled bilayer InAs/GaAs quantum dots (QDs)", Proc. SPIE 9758, Quantum Dots and Nanostructures: Growth, Characterization, and Modeling XIII, 97580T (15 March 2016); https://doi.org/10.1117/12.2211749

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