[Comparative study on photoluminescence from Ge/PS and Ge/SiO2 thin films]

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Context:

• Germanium (Ge) and silicon oxide (SiO2) thin films are crucial in optoelectronic devices.
• Porous silicon (PS) offers a unique nanostructure for material integration.
• Understanding photoluminescence mechanisms in Ge-based nanostructures is vital for device applications.

Purpose:

• To comparatively study the photoluminescence properties of Ge thin films deposited on porous silicon (Ge/PS) and Ge-containing silicon oxide (Ge/SiO2) thin films.
• To investigate the influence of sputtering time (for Ge/PS) and Ge content (for Ge/SiO2) on photoluminescence.
• To elucidate the underlying mechanisms responsible for photoluminescence in both Ge/PS and Ge/SiO2 systems.

Summary:

• Ge thin films were deposited on PS and n-type Si substrates (forming Ge/SiO2) via RF magnetron sputtering, followed by annealing.
• Fourier-transform infrared spectroscopy (FTIR) revealed structural changes, including the formation of Si-O-Si networks and new Si-Ge, Ge-Ge, and Ge-O bonds.
• Photoluminescence peaks were observed at 517 nm for Ge/PS and 580 nm for Ge/SiO2, with intensities significantly affected by sputtering parameters but minimally by annealing temperature.
• Ge/PS photoluminescence is attributed to Ge-related defects at interfaces, while Ge/SiO2 emission originates from luminescence centers within the Si oxide matrix.

Impact:

• Provides insights into the distinct photoluminescence mechanisms of Ge/PS and Ge/SiO2 thin films, despite structural similarities.
• Highlights the role of sputtering parameters in tuning photoluminescence intensity.
• Offers foundational knowledge for designing and optimizing Ge-based nanostructured materials for optoelectronic applications.