Auger recombination and carrier multiplication in embedded silicon and germanium nanocrystals

Abstract

For Si and Ge nanocrystals (NCs) embedded in wide band-gap matrices, Auger recombination (AR) and carrier multiplication (CM) lifetimes are computed exactly in a three-dimensional real space grid using empirical pseudopotential wave functions. Our results in support of recent experimental data offer new predictions. We extract simple Auger constants valid for NCs. We show that both Si and Ge NCs can benefit from photovoltaic efficiency improvement via CM due to the fact that under an optical excitation exceeding twice the band gap energy, the electrons gain lion's share from the total excess energy and can cause a CM. We predict that CM becomes especially efficient for hot electrons with an excess energy of about 1 eV above the CM threshold.

4 pages, 6 figures (Published version)

References in corpus (3)

• High Efficiency Carrier Multiplication in PbSe Nanocrystals: Implications for Solar Energy
• Interband, intraband and excited-state direct photon absorption of silicon and germanium nanocrystals embedded in a wide band-gap lattice
• Screening in semiconductor nanocrystals: \textit{Ab initio} results and Thomas-Fermi theory

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