Laser crystallized low-loss polycrystalline silicon waveguides.

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Integrated circuits require efficient light manipulation components.
• Polysilicon is a cost-effective material, but achieving high crystalline quality for optical applications is challenging.
• Existing methods for polysilicon waveguide fabrication often involve high temperatures incompatible with standard manufacturing processes.

Purpose of the Study:

• To fabricate low-loss polysilicon waveguides at low temperatures.
• To control grain growth and improve crystalline quality for optical applications.
• To assess the compatibility of the fabrication process with Complementary Metal-Oxide-Semiconductor (CMOS) integration.

Main Methods:

• Laser crystallization of amorphous silicon films.
• Pre-patterning of amorphous silicon to confine thermal energy during crystallization.
• Characterization using Micro-Raman spectroscopy, Secco etching, and X-ray diffraction.
• Optical loss measurements.

Main Results:

• Achieved low-loss polysilicon waveguides with optical losses as low as 5.3 dB/cm.
• Demonstrated high crystalline quality with the formation of millimeter-long crystal grains.
• The laser crystallization process, with pre-patterning, effectively controlled grain growth and minimized heat dissipation.
• The fabrication method is compatible with CMOS integration due to its low-temperature nature.

Conclusions:

• Laser crystallization is a viable technique for fabricating high-quality, low-loss polysilicon waveguides.
• The developed method offers a pathway for creating advanced optical components for high-density integrated circuits.
• The CMOS-compatible, low-temperature process enables scalable production of polysilicon photonic devices.