Silicon crystallinity control during laser direct microstructuring with bursts of picosecond pulses

Area of Science:

• Materials Science
• Laser Physics
• Nanotechnology

Background:

• Laser-based fabrication offers precise material modification.
• Controlling laser-matter interactions is key for advanced manufacturing.
• Silicon's unique properties make it suitable for optical applications.

Purpose of the Study:

• To demonstrate precise control over laser ablation and modification of bulk silicon.
• To achieve homogeneous surface properties with controlled crystallinity, depth, and topography.
• To explore different laser-matter interaction regimes for silicon processing.

Main Methods:

• Utilizing bursts of picosecond laser pulses with a tightly focused beam.
• Employing a custom fiber laser source generating variable pulse bursts (1-20 pulses) at high repetition rates (40 MHz pulse, 83.3 kHz burst).
• Systematically varying pulse energy, pulse positioning, and number of pulses per burst.

Main Results:

• Achieved precise control over surface crystallinity, structure depth, and topography.
• Demonstrated homogeneous surface properties across processed areas.
• Controlled transitions through different laser-matter interaction regimes: no change, amorphization, and ablation with varying amorphization levels.
• Defined single micrometer-sized areas with submicron precision.

Conclusions:

• Picosecond pulse burst laser ablation provides a versatile tool for silicon microstructuring.
• The method allows for controlled fabrication of silicon structures with tailored properties.
• This technique holds promise for advanced applications in optics and photonics.