Femtosecond Laser Irradiation

About

Background Silicon has become widely used throughout the electronics industry because of its cost efficiency and availability. Yet, silicon has not been utilized in the production of optoelectronic devices that detect infrared (IR) light due to the large band gap of the solid silicon surface. Researchers have previously developed a method to increase the IR absorbance of silicon using femtosecond laser irradiation with the presence of a background gases to dope the silicon surface to achieve absorption of IR light with photon energy less than 1.1 eV.  However, the environments needed to employ methods are costly to achieve. Technology UMass Lowell researchers have developed a novel method of femtosecond laser irradiation of the silicon surface to be used for IR detecting optoelectronic devices in air without the presence of background gases. The irradiation process transforms the solid silicon surface to a composite of nano-crystalline silicon and embedded amorphous silicon to increase the absorbance if IR light. The amorphous silicon structure provides energy states within the IR absorption energy band gap, and has shown to increase the optical absorbance of IR light by almost 50% when compared to the solid silicon substrate. Advantages Silicon material is a cost efficient approach to manufacturing optoelectronic sensors. Unique femtosecond laser irradiation method does not require expensive and complicated facilities. Amorphous silicon is easier to generate as it is embedded in the nano-crystalline layer. Applications Infrared sensors and detectors. Gas sensors and analyzers. Flame sensors. Spectral analysis devices. Contact-free temperature thermometers. Intellectual Property​ Patent pending.