Optical Absorption Enhancement in CdTe Thin Films by Microstructuration of the Silicon Substrate

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Thin films of Cadmium Telluride (CdTe) are crucial for optoelectronic devices.
• Controlling film properties through substrate engineering is an active research area.
• Laser ablation offers precise surface modification capabilities.

Purpose of the Study:

• To investigate the impact of microstructured substrates on CdTe thin film properties.
• To quantify changes in reflectance, optical absorption, and band gap.
• To compare films grown on planar versus laser-ablated silicon.

Main Methods:

• CdTe thin films were deposited using pulsed laser ablation at 200 °C.
• Silicon substrates were microstructured using periodic laser ablation.
• X-ray diffraction and Raman spectroscopy confirmed CdTe presence and structure.
• Fresnel laws were applied to experimental reflectance data for optical absorption calculation.

Main Results:

• Reflectance of 245 nm CdTe films on microstructured substrates was reduced by up to 50%.
• Optical absorption increased by 16% at ~456 nm for films on modified substrates.
• Band gap energy remained consistent at approximately 1.44 eV for both planar and microstructured films.

Conclusions:

• Laser ablation-induced microstructuring effectively enhances optical absorption of CdTe thin films.
• Surface modification via periodic structuring is a viable strategy for optimizing thin film optoelectronic performance.
• The band gap remains unaffected, suggesting potential for tailored light absorption in devices.