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In present work, zinc oxide (ZnO) nanoparticles are decorated on the surface of Vertically Aligned-Single Wall Carbon Nanotubes (VA-SWCNTs) to enhance field emission properties of SWCNTs. VA-SWCNTs synthesized by Plasma Enhanced Chemical Vapour Deposition (PECVD) technique are decorated with ZnO nanoparticles by thermal evaporation technique. Modified surface morphologies of as-prepared films were characterized by Atomic Force Microscope (AFM) and Raman spectroscopy to confirm the attachment of ZnO nanoparticles on VA-SWCNTs. Remarkable increase in current density, stability as well as reduction in turn on field were observed in ZnO nanoparticles coated VA-SWCNTs. Attachment of ZnO nanoparticles reduce the turn-on field of VA-SWCNTs field emitters from 2.0 to 1.0 V/μm, while current density increase from 3.6 to 16.8 mA/cm 2 with long term stability and repeatability. The observed results are explained in terms of increased emitting area by modified surface with high field enhancement factor of VA-SWCNTs field emitters. [ABSTRACT FROM AUTHOR]

Here we have reported gas sensor properties of pristine single walled carbon nanotubes (SWCNTs) and Gold (Au) nanoparticles decorated SWCNT sensor towards trace level concentration detection of NH 3 (40 ppm) at an operating temperature of (40 °C). Random network of SWCNTs were successfully synthesized by plasma enhanced chemical vapor deposition (PECVD) technique at a temperature of (650 °C). Two varied sets of chemiresist sensors were fabricated. One set of sensors was pristine SWCNT and the other set was decorated with Au nanoparticles by simple cast effective spray coating method. Morphological study was done by FESEM and HRTEM which revealed the excellent growth of SWCNTs and proper decoration of Au nanoparticles. The diameter distribution was confirmed by Raman Spectroscopy. The sensor response performances of both the fabricated set of sensors were analyzed and compared. The Au nanoparticles decorated SWCNT sensor had shown excellent enhancement in sensitivity. Fast response, speedy recovery, high resistance variation, high quality repeatability, long term stability and excellent selectivity was observed by Au decorated SWCNT sensor as compared to pristine SWCNT sensor for the NH 3 detection. In addition of this, the sensor response and response recovery time has shown an increase with the increasing rate of target gas concentration. The sensor response also shows a decrease with increasing relative humidity. [ABSTRACT FROM AUTHOR]

An ideal vacuum-based electron emitter requires a low turn-on field and quick emission processes. Carbon nanotubes (CNTs) have great potential for emission applications, but have some limitations that affect their performance. Consequently, they can benefit from the alteration of their surface morphology upon decoration with plasma-based metal nanoparticles. In this work, we have attached iron nanoparticles on the CNTs surface via a radio frequency (rf) sputtering process using Ar + N 2 gas with various plasma power in steps of 50 W. Field emission scanning electron microscopy (FESEM) micrographs have confirmed the attachment of the iron nanoparticles and etching of the nanotubes surface at high plasma power. The Raman spectra strongly confirm the formation of defects in the carbon sheet of the nanotubes. In the plasma treatment process, the increase in the D b a n d intensity enhanced the degree of disorder and may be beneficial for enhanced emission properties. The field electron emission properties are significantly enhanced after the Fe nanoparticles attached with plasma incorporated in terms of the reduction in E t o (1.64 from 2.02 V/μm) & E t h (1.98 from 2.64 V/μm), and increase in J (391.11–1179.24 μA/cm2) and β (1419–2900), respectively. The field emission parameters of the field emitters are modified due to incorporation of nitrogen species, attached Fe nanoparticles, and reduction in the nanotube density. The as-prepared field emitters also qualified the orthodox field emission hypothesis test by exhibiting f e x t r values in an acceptable range. Therefore, we can use the Ar + N 2 plasma-based Fe nanoparticles decorated CNT field emitters in vacuum electronic device applications. [Display omitted] • The field emission parameters of CNT field emitters drastically improved after the power-dependent plasma process. • The E t o and E t h fields get reduced and J increased due to the incorporation of defects, nitrogen, and Fe nanoparticles. • The extracted field emission area decreased as the power of the Ar + N 2 gas plasma increased. • The temporal emission stability improved due to the reduction in the screening field effect because of emitters etched. [ABSTRACT FROM AUTHOR]

Fig. Ammonia Gas Sensor and Field Emission modal with obtained Respective Results • Long network of RO-SWCNTs and VA-SWCNTs were separately grown by PECVD technique. • The electron microscopes have revealed the uniform and high quality structures of as grown SWCNTs. • VA-SWCNTs and RO-SWCNTs based sensors were fabricated for gas sensing studies. • The field emission studies of VA-SWCNTs and RO-SWCNTs were also performed using diode set up. • VA-SWCNTs were observed to be best for FEDs whereas RO-SWCNTs were observed to be excellent for gas sensors. Vertically aligned single wall carbon nanotubes (VA-SWCNTs) and randomly oriented (RO) SWCNTs have been successfully grown on Silicon (Si) substrate at an operating temperature of 650°C by plasma enhanced chemical vapour deposition (PECVD) technique. In the present work, two sets of sensors (RO-SWCNTs & VA-SWCNTs) were fabricated. An excellent enhancement in sensor response about 200–250% was achieved by RO-SWCNTs sensor while for VA-SWCNTs sensor, it was observed to be 80–100% at constant concentration of NH 3 (40 ppm) and at a temperature of 40°C. Fast response/recovery time characteristics with accurate repeatability and long term stability were observed in sensitivity. It was also observed that as-fabricated sensors are more selective towards NH 3. In field emission studies, field enhancement factor 1.2 × 104 at turn on voltage 2.8 V/μm and with current density 3 mA/cm2 was measured by VA-SWCNTs while for RO-SWCNTs the field enhancement factor was calculated 3.8 × 103 at turn-on voltage 4 V/μm with current density 1.7 mA/cm2. [ABSTRACT FROM AUTHOR]