Efficiency improvement of quantum well solar cell with the AuGeNi metallization and Si₃N₄ ARC design

Abstract

This study demonstrates the power conversion efficiency enhancement on In_0.19Ga_0.81As/GaAs quantum well solar cells (QWSC). The solar cell structure was grown on n-type (100)-oriented GaAs substrate by using solid-source molecular beam epitaxy technique and divided into square pieces. In order to understand whether the eight quantum wells were grown or not, scanning electron microscopy (SEM), and secondary ion mass spectrometry characterizations were done at room temperature. After that, the Si₃N₄ antireflection layers were coated onto both two square pieces of In_0.19Ga_0.81As/GaAs QWSC structure and p-GaAs substrate at different temperatures by the radio frequency magnetron sputtering system. The optical properties of the Si₃N₄ coated and uncoated p-GaAs samples have been evaluated by means of ultraviolet-visible spectrometry measurements at room temperature. According to ultraviolet-visible spectrometry results, the best Si₃N₄ antireflection coated one was obtained at 100 °C substrate temperature. Thus, the In_0.19Ga_0.81As/GaAs QWSC structure with and without Si₃N₄ layer, which was coated at 100 °C substrate temperature, was selected for other measurements and processes. Moreover, the In_0.19Ga_0.81As/GaAs QWSC samples with and without Si₃N₄ antireflection coating were separately fabricated with different metallization materials for obtaining the solar cell electrical output parameters. AuGe and AuGeNi metallization materials were used for the fabrication processes. After fabrication, the electrical output parameters were extracted from the current-voltage measurements at room temperature both in dark and under AM1.5 – 1 Sun illumination. The proposed design which includes the AuGeNi metallization and Si₃N₄ antireflection layer enhanced the power conversion efficiency by 44.40%.

Keywords:

• InGaAs/GaAs
• QWSC
• silicon nitride
• MBE
• SIMS
• SEM
• AFM
• I–V
• efficiency improvement

Acknowledgments

The authors would like to thank Institute of Materials for Electronics and Magnetism (IMEM-CNR) for SEM and Hiden Analytical Ltd. for SIMS measurements.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Republic of Turkey Ministry of Development [project number 211K120290]; The Scientific and Technological Research Council of Turkey (TUBİTAK) [project number 110T333].