In‐plane coupling effect on absorption coefficients of InAs/GaAs quantum dots arrays for intermediate band solar cell

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In‐plane coupling effect on absorption coefficients of InAs/GaAs quantum dots arrays for intermediate band solar cell

Tomić, Stanko

Coupled semiconductor quantum dot (QD) arrays emerged recently as promising structures for the next generation of high efficiency intermediate band solar cell (IBSC), because of their ability to facilitate the formation of minibands. The quantum coupling effect that exists between states in QDs in an array influences the electronic and optical properties of such structures. So far, great experimental and theoretical efforts have been devoted to study the vertically coupled QD arrays. We present here a method based on multi‐band k ⋅ p Hamiltonian combined with periodic boundary conditions, applied to predict the electronic and optical properties of InAs/GaAs QDs‐based lateral QD arrays. Formation of the intermediate band (IB) in all cases was achieved via delocalisation of the electron ground state ( e 0). We show that the IB in a laterally coupled QD‐IBSC is more robust against external electric field from the solar cell's pn junction than that in a vertically coupled arrangement. Because of symmetry of the QD array lattice and QD states itself, which are C 2 v for the zinc blend QDs, the electronic and absorption structures were obtained via sampling throughout the reciprocal space in the first Brillouin zone of QD arrays. Copyright © 2014 John Wiley & Sons, Ltd. Schematic of idealised laterally coupled 2D quantum dot (QD) array structure made of InAs/GaAs QDs is shown. The first Brillouin zone along with few characteristic points in 2D can describe such surface geometry. Variation of the band structure throughout the 2D BZ can then be used in the analysis of QD‐based intermediate band solar cell performance.