Thermal Stability of the Copper and the AZO Layer on Textured Silicon

Ping-Hang Chen,Wen-Jauh Chen,Jiun-Yi Tseng

doi:10.3390/coatings11121546

Ping-Hang Chen, Wen-Jauh Chen + Show 1 more

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https://doi.org/10.3390/coatings11121546

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Journal: Coatings	Publication Date: Dec 16, 2021
Citations: 4	License type: CC BY 4.0

Affiliation: National Yunlin University of Science and Technology

Abstract

Transparent conductive oxide (TCO) film is the most widely used front electrode in silicon heterojunction (SHJ) solar cells. A copper metallization scheme can be applied to the SHJ process. The abundance of zinc in the earth’s crust makes aluminum-doped zinc oxide (AZO) an attractive low-cost substitute for indium-based TCOs. No work has focused on the properties of the copper and AZO layers on the textured silicon for solar cells. This work deposited an aluminum-doped zinc oxide layer and copper metal layer on textured (001) silicon by a sputtering to form Cu/AZO/Si stacks. The structures of Cu/AZO/Si are characterized by scanning electron microscope (SEM), scanning transmission electron microscope (STEM), and energy-dispersive X-ray spectrometer (EDS). The results show that the copper thin film detached from AZO in the valley of the textured silicon substrate at a temperature of 400 °C. Additionally, the gap between the copper and AZO layers increases as temperature increases, and the 65 nm thickness AZO layer was found to be preserved up to 800 °C.

Highlights

In silicon heterojunction (SHJ) solar cells, the hydrogenated amorphous silicon (a-Si:H) thin layer is too low in transverse conductivity to collect charge carriers horizontally over the metal electrodes effectively
Finding a replacement for ITO could reduce the costs of the production of SHJ solar cells
In SHJ technology, the metallic contacts are generally deposited on a transparent conductive oxide (TCO)

Summary

Introduction

In silicon heterojunction (SHJ) solar cells, the hydrogenated amorphous silicon (a-Si:H) thin layer is too low in transverse conductivity to collect charge carriers horizontally over the metal electrodes effectively. Additional transparent conductive oxide layers such as Sn-doped In2O3 (ITO) are deposited at the top. Finding a replacement for ITO could reduce the costs of the production of SHJ solar cells. Compared with ITO, AZO has high thermal stability and a low price, and is mineral-rich, relatively non-toxic, and has an increased transparency of the visible light range, as well as other advantages [3,4,5,6].

Results

Conclusion