FeiGe Catalyzed Carbon Nanotube Growth on Hf02 for Nano-Sensor Applications

A carbon nanotube (CNT) growth process on Hf02 is reported for the first time for application in nano-sensors, The process uses a combination of Ge nanoparticles and ferric nitrate dispersion and achieves an increase in CNT density from 0.15 to 6.2 11m length/um" compared with the use of ferric nitrate dispersion alone. The growth process is validated by the fabrication of back-gate CNT field-effect transistors (CNTFETs) using AI source/drain (SID) contacts and a "2 anneal at 400°C. The transistors exhibit p-FET behavior with an Iml1offratio of 10 and a steep sub-threshold slope of 130 mY/dec. These results are rather sur prising, as earlier research in the literature on CNTFETs with AI SID electrodes showed n-FET behavior. The p-FET behavior is shown to be due to the H2 anneal, which we ascribe to the smaller electron affinity of hydrogenised CNTs . Measurements of the temperature dependence of the drain current show low Schottky barrier height AI SID contacts after a "2 anneal, which tends to confirm this explanation. (!) @ Ge e e (l) (a) PECVD Si0 2 Hf02 Ge nanoparticle formation Ferric nitrate dispersion CNT growth at 850 °C for 20 min Photolithography for SID contacts AI sputtering (150 nm)