Plasmonic visible-NIR photodetector based on hot electrons extracted from nanostructured titanium nitride

The superior plasmonic characteristics of transition metal nitrides have been widely considered for enhancing the performance of light-harvesting devices. We explore this fast-emerging field further and report here the successful implementation of titanium nitride (TiN) nanoparticles prepared by reactive magnetron sputtering in a broadband photodetector device geometry. X-Ray Photoelectron Spectroscopy study reveals the presence of two different phases, viz., titanium nitride and titanium oxynitride in the prepared TiN sample. These two different nitride phases lead to two plasmon absorption bands, one in the visible region and the other in the Near Infrared (NIR) region of the electromagnetic spectrum, which is a fascinating finding of this study. The fabricated photodetector shows appreciable photoelectrical response in the visible as well as in the NIR region due to plasmon induced charge separation aided by the TiN nanoparticles. Very high photoresponsivities of 158 mA/W and 230 mA/W of the device at wavelengths of 450 nm and 950 nm, respectively, make it very promising as a broadband photodetector. The corresponding Internal Quantum Efficiencies are found to be 48% and 35%, respectively, at those two particular wavelengths. The charge transport mechanism of the device is explained with an energy level diagram, which shows that the hot electrons produced from the decay of plasmon are responsible for the generation of photocurrent. Published under license by AIP Publishing.