Nanostructured Black Silicon

Image Credit: Georgy Shafeev/Shutterstock

Black silicon is a semiconductor material with a needle-shaped surface structure. It's similar to silicon but with a modified surface that has extremely low reflectivity and a high absorption rate of visible and infrared light. Black Silicon has helped researchers develop more efficient solar cells and it may also offer benefits for the medical sector.  

The needles on the surface are made of single-crystal silicon and measure above 10 µm in height and less than 1 µm in diameter.

When silicon is etched in a liquid solution at room temperature, black silicon is formed, however the black silicon is not black in color but dark due to the absence of reflected light from its porous surface.

Black silicon is being studied around the world for applications in numerous fields such as solar cells and medicine for its antibacterial properties.

Developments in Nanostructured Black Silicon

Researchers at Aalto University, Finland, have used black silicon to improve photovoltaic energy conversion efficiency using atomic layer deposition.

Nanostructured black silicon is capable of preventing any reflection over the full sun spectrum. Black silicon has the power to absorb solar energy under most circumstances such as early morning, late evening, and cloudy days, which is not possible with traditional solar cells.

The researchers hope that this finding can be applied on a large scale within silicon-based solar technology to help improve the efficiency in commercial photovoltaic cells.

Video Courtesy of Georgi Yankov YouTube Channel 

Another project from researchers at Swinburne University of Technology have discovered that black silicon has the capability of killing bacteria.

They believe that this finding will pave the way for new nano-structured antibacterial materials that can be used in various medical applications such as surfaces of medical implants.

Possible Applications

The following are the current applications of black silicon:

• Image sensors with very high levels of sensitivity
• Thermal imaging cameras
• Mechanical contacts and interfaces
• Terahertz applications
• Photodetectors with high-efficiency coupled with better absorption capacity

References

• Black silicon shows antibacterial power – Swinburne University of Technology
• Nanostructure-Coated Black Silicon Solar Cells Via ALD - Solar Novus Today
• Black Silicon - natcoretechnology