Thin-film platinum nanowires as sub-wavelength bolometers

Abstract

We present novel nanoscale bolometers made of lithographically defined platinum wires. The cores of our structures are narrow wires with fixed width of 300 nm and length ranging from 300 nm to 17 μm. Some are significantly smaller in size than the wavelengths they are exposed to from a 1200 K blackbody source. The response of the wire's resistance to the external radiation reflects its temperature and can be monitored in real-time. Previously, we have reported a steep rise in responsivity and detectivity with decreasing wire length under such infrared exposure, for a constant Joule power dissipation in the wire (drive power). In this work, we aim to enhance the performance of the bolometers by changing physical and driving parameters, i.e. the insulating layer thickness or the external bias. We find that after such optimization, structures can reach a responsivity R of 4.5x10 5 V/W and a detectivity D* of 2.3x10 10 cmHz 1/2/W. With a reduced size and a high performance, these devices could improve the infrared sensors technology. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).