Abstract
Intermediate band solar cells (IBSC) have been proposed as a potential design for the next generation of highly efficient photo-voltaic devices. Quantum nanostructures, such as quantum dots (QD), arranged in super-lattice (SL) arrays produce a mini-band (IB) that is separated by a region of zero density of states from other states in the conduction band. Additional absorption from the valence band to the IB and IB to the conduction band allows two photons with energies below the energy gap to be harvested in generating one electron-hole pair. We present a theoretical study of the electronic and optical properties of the IB formed by an InAs/GaAs QD array. The calculations are based on an 8-band k · p Hamiltonian, incorporating mixing between valence and conduction states, strain and piezoelectric field. Theoretical results of the the mini-band width variation with the period of the QD array in the z direction are presented. For one particular spacer distance, d z = 4 nm, we report detailed variation of the optical dipole matrix elements through the mini-band and identify the character of the states involved. This approach captures the essential physics of the absorption processes in a realistic model of the IBSC structure and will be used to provide input parameters for predictive modelling of transport properties.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Asryan L.V., Grundmann M., Ledentsov N.N., Stier O., Suris R.A., Bimberg D.: Maximum modal gain of a self-assembled InAs/GaAs quantum-dot laser. J. Appl. Phys. 90, 1666–1668 (2001)
Fry P. et al.: Inverted electron-hole alignment in InAs-GaAs self-assembled quantum dots. Phys. Rev. Lett. 84, 733–736 (2000)
Honsberg, C.B., Barnett, A.M.: Paths to ultra-high efficiency (>50%) photovoltaic devices. In: Proceedings of 20th European Photovoltaic Solar Energy Conference, pp. 453–456 (2005)
Ru E.C., Howe P., Jones T.S., Murray R.: Strain-engineered InAs/GaAs quantum dots for long-wavelength emission. Phys. Rev. B 67, 165303 (2003)
Luque A., Marti A.: Increasing the efficiency of ideal solar cells by photon induced transitions at intermediate levels. Phys. Rev. Lett. 78, 5014–5017 (1997)
Marti A. et al.: Production of photocurrent due to intermediate-to-conduction-band transitions: a demonstration of a key operating principle of the intermediate-band solar cell. Phys. Rev. Lett. 97, 247701 (2006)
Stier O., Grundmann M., Bimberg D.: Electronic and optical properties of strained quantum dots modeled by 8-band k · p theory. Phys. Rev. B 59, 5699–5701 (1999)
Tomić S., Sunderland A.G., Bush I.J.: Parallel multi-band k · p code for electronic structure of zinc blend semiconductor quantum dots. J. Mater. Chem. 16, 1963–1972 (2006a)
Tomić S., Howe P., Harrison N.M., Jones T.S.: Theoretical analysis of strain and strain decay in InAs/GaAs (001) multilayer quantum dot growth. J. Appl. Phys. 99, 093522 (2006b)
Vukmirović N. et al.: Symmetry of k · p Hamiltonian in pyramidal InAs/GaAs quantum dots: application to the calculation of electronic structure. Phys. Rev. B 72, 075356 (2005)
Vukmirović, N., Tomić, S.: Plane waves methodology for single quantum dot electronic structure calculations. J. Appl. Phys. 103, 103718 (2008)
Wei G., Forrest S.R.: Intermediate-band solar cells employing quantum dots embedded in an energy fence barrier. Nano Lett. 7, 218–222 (2007)
Xie Q., Madhukar A., Chen P., Kobayashi N.P.: Vertically self-organized InAs quantum box islands on GaAs(100). Phys. Rev. Lett. 75, 2542–2545 (1995)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Tomić, S., Harrison, N.M. & Jones, T.S. Electronic structure of QD arrays: application to intermediate-band solar cells. Opt Quant Electron 40, 313–318 (2008). https://doi.org/10.1007/s11082-008-9228-3
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11082-008-9228-3