Effect of various capping layer on the hydrostatic and biaxial strain of InAs QDs in x (100) and z (001) direction

Jhuma Saha; Debiprasad Panda; Debabrata Das; Vinayak Chavan; Subhananda Chakrabarti

doi:10.1117/12.2289961

21 February 2018 Effect of various capping layer on the hydrostatic and biaxial strain of InAs QDs in x (100) and z (001) direction

Jhuma Saha, Debiprasad Panda, Debabrata Das, Vinayak Chavan, Subhananda Chakrabarti

Author Affiliations +

Proceedings Volume 10543, Quantum Dots and Nanostructures: Growth, Characterization, and Modeling XV; 105430U (2018) https://doi.org/10.1117/12.2289961
Event: SPIE OPTO, 2018, San Francisco, California, United States

Abstract

The hydrostatic (ε_hy) and biaxial (ε_bi) strain in lateral (x) and growth (z) direction have been computed and compared for InAs quantum dot (QD) with different capping. The capping layers are: GaAs, InGaAs/GaAs, InAlGaAs/GaAs, InGaAs/InAlGaAs/GaAs, InAlGaAs/InGaAs/GaAs, and the total thickness is kept constant for all QD structures. The strain distribution is mainly confined within the dot and dies down towards the capping layer. The movement of conduction band edges is controlled by hydrostatic strain. QDs capped with InAlGaAs/InGaAs/GaAs and InAlGaAs/GaAs shows lower magnitude of ε_hy, which indicates better carrier confinement as compared to other capping. The electrostatic potential obtained for the InAlGaAs capped QDs is larger (~0.5 V) than other structures. The valence band splitting into the heavy hole and light hole depends on the biaxial strain. It is observed that GaAs and InAlGaAs/InGaAs/GaAs capping has the smallest and largest values of ε_bi respectively in the growth direction. The GaAs capped QD structure has a smaller ε_bi, which would increase the energy of the ground state hole, leading to blue shift in photoluminescence spectrum. However, the ground hole state has a lower energy due to larger ε_bi in InAlGaAs/InGaAs/GaAs capped QD, which results in a red shift in the photoluminescence spectrum (~1.35 μm at 300 K). Nonetheless, InAlGaAs capped QDs shows better results in the lateral direction also. Thus, based on the strain profile, QDs capped with InAlGaAs as the first capping layer is the optimized structure which can be useful for various optoelectronic applications.

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Jhuma Saha, Debiprasad Panda, Debabrata Das, Vinayak Chavan, and Subhananda Chakrabarti "Effect of various capping layer on the hydrostatic and biaxial strain of InAs QDs in x (100) and z (001) direction", Proc. SPIE 10543, Quantum Dots and Nanostructures: Growth, Characterization, and Modeling XV, 105430U (21 February 2018); https://doi.org/10.1117/12.2289961

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