Theoretical Modeling and Simulation of Electronic Band Structure and Properties of InAs/GaAs Superlattice

H.I. Ikeri¹ , A.I. Onyia² , P.U. Asogwa³

Section:Research Paper, Product Type: Journal-Paper
Vol.8 , Issue.5 , pp.28-37, Oct-2020

Online published on Oct 31, 2020

Copyright © H.I. Ikeri, A.I. Onyia, P.U. Asogwa . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
 

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Abstract :
Theoretical modeling of the electronic band structure and simulation results of InAs/GaAs quantum dots superlattices (QDSL) is presented. Time independent Schrödinger equation (SE) within the envelope function approximation was applied in connection with Kronig-Penney model to calculate the electronic band structure of the InAs QD embedded in the matrix of GaAs semiconductor. The simple model obtained reveals that SL exhibits a complex band structure consisting of dispersion with real and imaginary components of Bloch wave vector. The corresponding real band structure suggests delocalized propagating electron states in the crystal (energy band region) whereas the imaginary band structure signifies localized non-propagating electron states (forbidden region). It is observed that energy width of these bands is smaller than the normal conduction bands due to the additional periodicity in the system. Thus, the energy bands originating from the superlattice structure are called minibands. Results have shown that when a finite inter dot spacing is maintained so that there is significant wave function overlap between quantum wells, the discrete energy levels associated with the individual QDs split, leading to the formation of bands. The electronic and optical properties associated with these minibands are found to be dependent on the device parameters such as QD width and barrier thickness. We have calculated electronic and optical properties which include ground state energies, bandwidths, transition energies, density of states, absorption coefficient and refractive index at varying QD width and barrier thickness. Results show monotonous decrease in the ground state energy and the formation of multiple bands with increasing QD width (2.5nm – 12.5nm), whereas increasing the barrier thickness in the allowable range (2.5nm–4.5nm) results in a higher bandwidth. A maximum absorption coefficient of 1.3×104?cm?1 was calculated for the system, which can be very useful for sensitive photonic devices such as high efficiency intermediate band solar cells and infrared detectors.

Key-Words / Index Term :
Bandgap, Barrier thickness, Electronic band structure, Kronig Penney model, Minibands, Quanum dot width, Schrodinger equation, Superlattice

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