Calculation of the quantum efficiency for the absorption on confinement levels in quantum dots
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The quantum efficiency of the absorption on quantum confinement levels is investigated. This is achieved by modeling the electron confinement in a spherical quantum dot (QD). The confinement levels are calculated using both infinite and finite rectangular quantum wells. The spectral internal quantum efficiency is evaluated within both the models, by computing Einstein’s coefficients for the transitions between confinement levels. The size of QDs (1–3 nm radius) leads to negligible many body effects. The nature of the QD material and of the matrix embedding is taken into account in the finite rectangular quantum well approximation and introduces only a small correction. The temperature dependence of the efficiency is also taken into account. A numerical application is performed for a silicon QD of 2.5 nm radius, embedded in amorphous silica. It is proved that the absorption threshold shifts toward the far infrared limit and that the spectral internal quantum efficiency reaches 4–5% at the threshold.
KeywordsLight absorption Quantum confinement Quantum dots Quantum efficiency Solar cells
This work was supported from Project No. 471/2009 (ID 918/2008), Ideas Program, National Research, Development and Innovation Plan 2007–2013.
- Bányai L, Koch SW (1993) Semiconductor quantum dots. World Scientific, Singapore ISBN: 981-02-1390-5Google Scholar
- Ciurea ML, Iancu V (2009) Quantum confinement in nanometric structures. In: Baleanu D, Güvenç ZB, Tenreiro Machado JA (eds) New trends in nanotechnology and fractional calculus applications. Springer, Heidelberg, pp 57–67 ISBN: 978-90-481-3292-8Google Scholar
- Haug H, Koch SW (2001) Quantum theory of the optical and electronic properties of semiconductors, 3rd edn. World Scientific, Singapore ISBN: 978-981-02-1864-5Google Scholar
- Huang DH, Lyo SK, Gumbs G (2009) Bloch oscillation, dynamical localization, and optical probing of electron gases in quantum-dot superlattices in high electric fields. Phys Rev B 79:1–19, 155308. doi: 10.1103/PhysRevB.79.155308
- Lang IG, Pavlov ST (2009) Resonant light absorption by semiconductor quantum dots. Adv Condens Matter Phys 2009:1–7, 654190. doi: 10.1155/2009/654190
- Nozik AJ (2003) Advanced concepts for photovoltaic cells. In: NCPV and Solar Program Review Meeting 2003, NREL/CD-520-33586, pp 422–426. http://www.uio.no/studier/emner/matnat/kjemi/MENA5020/h07/undervisningsmateriale/solarcells.pdf
- Popescu V, Bester G, Hanna MC, Norman AG, Zunger A (2008) Theoretical and experimental examination of the intermediate-band concept for strain-balanced (In,Ga)As/Ga(As,P) quantum dot solar cells. Phys Rev B 78:1–17, 205321. doi: 10.1103/PhysRevB.78.205321