Guidelines for establishing an etching procedure for dislocation density measurements on multicrystalline silicon...

Area of Science:

• Materials Science
• Photovoltaics
• Semiconductor Physics

Background:

• Multicrystalline silicon is key for solar cells, but dislocations limit efficiency.
• Etch pit density measurements are vital for quantifying these defects.
• Existing etchants are often optimized for monocrystalline silicon, requiring adaptation for multicrystalline variants.

Purpose of the Study:

• To compare the PVScan tool with microscope image analysis for etch pit density measurements.
• To investigate the impact of etching methods on dislocation density results.
• To optimize the Sopori etching procedure for multicrystalline silicon and evaluate it as a safer alternative to Secco etchant.

Main Methods:

• Selective etching of silicon samples.
• Utilizing the PVScan tool for rapid dislocation density assessment.
• Employing microscope image analysis for quantitative defect analysis.
• Comparing Sopori and Secco etchants for multicrystalline silicon.

Main Results:

• Etching methods significantly influence etch pit density measurement outcomes.
• The Sopori etching procedure was optimized for high-dislocation-density multicrystalline silicon.
• Sopori etchant provides comparable precision to Secco etchant for dislocation density measurements.
• Sopori etchant avoids toxic hexavalent chromium compounds present in Secco etchant.

Conclusions:

• Optimized Sopori etching offers a precise and safer method for assessing dislocation density in multicrystalline silicon.
• This advancement can contribute to improved solar cell efficiency by better material characterization.
• The findings support the adoption of chromium-free etchants in photovoltaic material analysis.