AVS 65th International Symposium & Exhibition
    Thin Films Division Monday Sessions
       Session TF-MoA

Paper TF-MoA4
Single Junction GaAs Thin Film Solar Cells on Flexible Metal Tapes for Low Cost Photovoltaics

Monday, October 22, 2018, 2:20 pm, Room 104B

Session: IoT Session: Thin Films for Photovoltaics
Presenter: Devendra Khatiwada, University of Houston
Authors: D. Khatiwada, University of Houston
M. Rathi, University of Houston
P. Dutta, University of Houston
S. Sun, University of Houston
Y. Yao, University of Houston
Y. Gao, University of Houston
Y. Li, University of Houston
S. Pouladi, University of Houston
J.-H. Ryou, University of Houston
V. Selvamanickam, University of Houston
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III-V semiconductor materials like GaAs that have a high absorption coefficient in the relevant energy range for photovoltaic absorbs most of the sunlight within small range beneath the surface. Highest efficiencies have been reported in III-V solar cells based on GaAs wafer. However, its application has been very limited due to high cost of these wafers. We develop a technology to provide high quality epitaxial semiconductor thin films on low-cost flexible metal tapes by roll to roll fabrication to overcome the wafer cost .

Herein, we introduce high quality epitaxial semiconductor thin film on low cost flexible metal (Hastelloy) to provide flexibility and overcome the wafer cost with roll to roll processing. Firstly, polycrystalline to single crystalline like material were grown on the flexible metal tape over which biaxially textured Germanium (Ge) thin film were grown. Finally, epitaxial (Al) GaAS semiconductor thin films were grown on the biaxially textured Ge thin films using Metal Organic Chemical Vapor Deposition (MOCVD). The device were further processed for contact deposition via photolithography process.

The fabricated thin film III-V solar cells showed promising photovoltaic efficiency under A.M 1.5G with front illumination geometry. Photon conversion efficiency greater than 11% was observed under A.M 1.5 (1 sun) with open circuit voltage (VOC) of 642mV, short circuit current density (JSC) of 25mA/cm2 and fill factor (FF) of 70% . Further improvement in device efficiency is achieved with new device architectures, optimization of the growth and improving fabrication processes.

This work was partially funded by the U.S. Department of Energy Sunshot Initiative.