Three-dimensional imaging for precise structural control of Si quantum dot networks for all-Si solar cells

Lena F. Kourkoutis*, Xiaojing Hao, Shujuan Huang, Binesh Puthen-Veettil, Gavin Conibeer, Martin A. Green, Ivan Perez-Wurfl

*Corresponding author for this work

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

All-Si tandem solar cells based on Si quantum dots (QDs) are a promising approach to future high-performance, thin film solar cells using abundant, stable and non-toxic materials. An important prerequisite to achieve a high conversion efficiency in such cells is the ability to control the geometry of the Si QD network. This includes the ability to control both, the size and arrangement of Si QDs embedded in a higher bandgap matrix. Using plasmon tomography we show the size, shape and density of Si QDs, that form in Si rich oxide (SRO)/SiO2 multilayers upon annealing, can be controlled by varying the SRO stoichiometry. Smaller, more spherical QDs of higher densities are obtained at lower Si concentrations. In richer SRO layers ellipsoidal QDs tend to form. Using electronic structure calculations within the effective mass approximation we show that ellipsoidal QDs give rise to reduced inter-QD coupling in the layer. Efficient carrier transport via mini-bands is in this case more likely across the multilayers provided the SiO2 spacer layer is thin enough to allow coupling in the vertical direction.

Original languageEnglish
Pages (from-to)7499-7504
Number of pages6
JournalNanoscale
Volume5
Issue number16
DOIs
Publication statusPublished - 21 Aug 2013
Externally publishedYes

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