Reactivation of infrared absorption in highly-doped silicon

Harvard University Office of Technology Development
posted on 07/09/2011

• request more info 
•   
•  LICENSE ONLINE

MARKETS ADDRESSED:
Highly-doped silicon (“black silicon”) is doped orders of magnitude above room temperature solubility. It is utilized in a range of applications including thin film silicon photovoltaics, in advanced devices such as intermediate-band solar cells and light sensing devices. It has near uniform absorption of photons, especially in broadband infrared absorption. Black silicon is currently manufactured with short-pulsed laser irradiation in the presence of chalcogens. However, the absorption properties of the material become degraded after subsequent processing (such as annealing).

A team of Harvard and MIT physicist led by Eric Mazur and Tonio Buonassisi have developed a technique to reactivate the infrared absorption in highly-doped silicon.

INNOVATIONS & ADVANTAGES:
This technology solved the problem of decreasing absorption in highly-doped silicon when subject to subsequent processing. It demonstrated that through higher temperature annealing (=1000°C) followed by a rapid cooling (e.g., in air or in oil), the infrared absorbance can be reactivated. This process allows for greater control of the active defect and the property of the material can be optimized with thermal processing.