Optical and electrical analysis of graded buffer layers in III–V/SiGe on silicon tandem solar cells

A graded buffer layer is needed in order to grow III-V/SiGe on silicon substrate because of the lattice mismatch. In this work, optical absorption in the graded buffer layer is quantified by measuring the transmittances. We demonstrate a 7 μm graded buffer layer with Ge composition from 0% to 82% is...

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Published in2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC) pp. 1 - 3
Main Authors Dun Li, Xin Zhao, Diaz, Martin, Conrad, Brianna, Li Wang, Soeriyadi, Anastasia H., Gerger, Andrew, Lochtefeld, Anthony, Barnett, Allen, Perez-Wurfl, Ivan
Format Conference Proceeding
LanguageEnglish
Published IEEE 01.06.2015
Subjects
Absorption
graded buffer layer
III-V semiconductor materials
Indexes
Indium phosphide
optical absorption
Optical variables measurement
Photovoltaic cells
Silicon
silicon germanium
tamdem solar cell
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Summary:A graded buffer layer is needed in order to grow III-V/SiGe on silicon substrate because of the lattice mismatch. In this work, optical absorption in the graded buffer layer is quantified by measuring the transmittances. We demonstrate a 7 μm graded buffer layer with Ge composition from 0% to 82% is equivalent to a 2 μm SiGe film with 82% Ge composition in terms of optical absorption. A SiGe solar cell was fabricated and characterized. Quantum efficiency measurements show that around 1 mA/cm 2 short circuit current is generated from the graded buffer layer in the fabricated solar cell.
DOI:10.1109/PVSC.2015.7356237