Ge-Sb-S-Se-Te amorphous chalcogenide thin films towards on-chip nonlinear photonic devices

Area of Science:

• Materials Science
• Optoelectronics
• Photonics

Background:

• Amorphous chalcogenide materials like Ge-Sb-S-Se-Te exhibit unique optical properties.
• The near and mid-infrared spectral ranges are crucial for photonics and optical sensor applications.

Purpose of the Study:

• To tailor the linear and nonlinear optical properties of GeSb$_{w}$S$_{x}$Se$_{y}$Te$_{z}$ chalcogenide thin films.
• To investigate the relationship between amorphous structure, optical properties, and thermal stability.
• To assess the suitability of these materials for CMOS-integrated microelectronics and photonics.

Main Methods:

• Co-sputtering technique using chalcogenide compound targets in a 200 mm industrial deposition tool.
• Spectroscopic ellipsometry for evaluating linear and nonlinear optical properties.
• Raman and Fourier-transform infrared spectroscopies for characterizing amorphous structure.
• Thermal annealing to evaluate thermal stability.

Main Results:

• Modification of the amorphous structure of GeSb$_{w}$S$_{x}$Se$_{y}$Te$_{z}$ films significantly tailors optical properties.
• Spectroscopic ellipsometry successfully modeled linear and nonlinear optical responses.
• Raman and FTIR spectroscopies provided insights into the amorphous structure.
• Thermal stability was evaluated upon annealing.

Conclusions:

• Composition-dependent trade-offs exist between infrared transparency, nonlinearity, and thermal stability.
• These chalcogenide films can be optimized for specific applications in near- and mid-infrared ranges.
• The materials show potential for integration into CMOS processes for microelectronics and photonics.