Tunable broadband absorption in continuous and porous textured Si/C bilayers: A comparative study

Effective light scattering, transmission and absorption play a pivotal role in optical devices. Significant progress has been recorded in this area via the application of surface texturing techniques and photo-friendly thin film coatings. Combining two facile and environmentally safe synthesis processes, a textured silicon (Si)/amorphous carbon (a-C) nanocomposite coating was formed on single crystal silicon substrates. A high purity silicon coating with the average thickness of 17 mu m was formed via in situ magnesiothermic reduction reaction (MRR) of diatomaceous earth (DE) and spherical nanosilica at 750 degrees C and followed by a facile phase separation between polyacrylonitrile (PAN)/tetraethyl orthosilicate (TEOS) to create a porous a-C film. The porous/continuous PAN thin films were subsequently carbonized at 850 degrees C resulting in a textured Si/a-C film nanocomposite. Unlike polished or textured silicon surfaces, the a-C coated textured silicon surface showed high broadband absorption in excess of 60% in the range 300-1700 nm that compares well with most textured surfaces reported recently in the literature, and benefits from a facile and eco-friendly fabrication approach.

Automated summary

Effective light scattering, transmission, and absorption are crucial for optical devices. This study presents a facile and eco-friendly method for fabricating a textured Si/a-C film nanocomposite with high broadband absorption. The combination of surface texturing techniques and photo-friendly thin film coatings has shown significant progress in this field.