PLD Growth of CNTs using a Nanostuctured Ni Buffer Layer: Dependence of H2 partial Pressure
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0951-E06-15
PLD Growth of CNTs using a Nanostuctured Ni Buffer Layer: Dependence of H2 Partial Pressure Maneesh Chandran1,2, K. Mohan Kant1,2, N. Rama1,2, and M.S. Ramachandra Rao1,2 1 Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India 2 Materials Science Research Centre, Indian Institute of Technology Madras, Chennai, 600036, India ABSTRACT The effect of hydrogen partial pressure on the growth of CNT thin films using on-axis PLD has been studied. Using nickel as buffer layer, carbon nanotubes can be produced with good yield in Hydrogen atmosphere. We have found strong visible-near infrared (NIR) photoluminescence (PL) from carbon nanotube thin films synthesized under various hydrogen partial pressures. The present result shows that bright, narrow PL from CNTs can be obtained without any post growth processing. INTRODUCTION The last decade of the last century in condensed matter physics has been marked by the revival of carbon based materials like fullerenes and carbon nanotubes. Since the discovery in 1991 [1], carbon nanotubes have attracted a lot of attention from the science community because of their interesting quasi-one-dimensional character. These tubes are also believed to have great application potentials in nanotechnology [2]. Recent reports of photoluminescence (PL) [3,4] from carbon nanotubes extend the possible applications to optoelectronics. The synthesis of CNTs using laser ablation in an inert atmosphere or in a nitrogen atmosphere has been reported previously [5,6]. The favorable temperature in this laser ablation method is 1200oC and the yield decreases drastically as the temperature decreases. However, for many potential applications we need to grow the CNTs at low temperature. There have been serious efforts to reduce the growth temperature. The CVD/PECVD methods are in a way of successful in reducing the growth temperature. In comparison to CVD/ PECVD method, PLD can give rise to more homogenous products with less defects and is thus a suitable technique to study the growth mechanism and other fundamental studies of CNTs. Unfortunately, the growth mechanism of CNT is not controlled or fully understood till this date. This shows the necessity to look into the fundamental studies of carbon nanotubes. Photoluminescence characterization, since it is rapid and large scale, should help in the effort to control nanotube diameter and chirality. The first reports on PL spectra of carbon nanotubes came after a decade of its invention, by Smalley group [7]. Since then, there has been a tremendous effort to study the PL of CNTs by various groups [8,9] because PL, in a significant way, can be used to study in fundamental physics of CNTs, monitoring and manipulating their electronic states. EXPERIMENT Here, we report on a complete in-situ synthesis root of CNT thin films using on-axis pulsed laser deposition (PLD) at relatively low growth temperature (700oC). We used Ni as a buffer layer, which gives nano-sized spherical islands 940-60nm) on the quartz substrate, followed
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