Raman Analysis of Si Crytallinity

Importance of the Topic

The degree of crystallinity in silicon films critically influences electronic, optical, and mechanical properties relevant to semiconductor devices and photovoltaic cells. Rapid, non-destructive assessment of silicon crystallinity supports process optimization, quality control, and material research in industrial and laboratory environments.

Objectives and Study Overview

This study evaluates the performance of a portable, high-resolution Raman spectrometer to distinguish amorphous and microcrystalline phases in mixed-phase silicon films. Two sample sets covering broad and narrow crystallinity ranges were analyzed to demonstrate sensitivity, resolution, and practical applicability.

Methodology and Instrumentation

Raman spectra were acquired using a 532 nm excitation laser under consistent optical conditions. Key components and procedures:

• Instrumentation: B&W Tek i-Raman (S) with 5 cm-1 resolution and 532 nm laser excitation; Video Microscope Sampling System BAC151A
• Sample Preparation: Silicon films deposited on glass substrates with controlled crystallinity rates
• Sample Groups: Group A spanning <10% to single crystal silicon; Group B within a 45–63% crystallinity range
• Data Acquisition: Raman spectra collected via the microscope coupling to ensure accurate focus and repeatability

Main Results and Discussion

Two characteristic Raman peaks indicate silicon phases: the amorphous phase peak at 480 cm-1 and the microcrystalline silicon peak at 520 cm-1. Observations include:

• Group A: A clear transition from a dominant 480 cm-1 peak in low-crystallinity samples to a dominant 520 cm-1 peak in high-crystallinity and single-crystal samples
• Group B: Samples in the 45–63% range show reduced variation between the two peaks, confirming narrower crystallinity differences
• Peak intensity shifts correlate directly with increasing crystallinity, demonstrating method sensitivity

Benefits and Practical Applications

The portable high-resolution Raman system provides rapid, non-destructive quantification of silicon crystallinity. Applications include in situ monitoring of thin film deposition, quality assurance in manufacturing lines, and field-deployable materials characterization.

Future Trends and Possibilities

Emerging directions for Raman-based crystallinity analysis:

• Integration with automated mapping for high-throughput spatial profiling
• Extension to other semiconductor materials and thin film systems
• Hybrid approaches combining Raman with complementary spectroscopic or imaging techniques

Conclusion

The B&W Tek i-Raman system coupled with a video microscope sampling setup effectively resolves key silicon Raman features, enabling accurate crystallinity assessment in both laboratory and field environments.

Reference

• Dawn Yang. Raman Analysis of Si Crystallinity. B&W Tek, Inc., Application Note, 2010.