Photoconductivity in defective carbon nanotube sheets under ultraviolet–visible–near infrared radiation

Abstract

Multiwalled carbon nanotube sheets of relatively large area have been grown on a sapphire substrate by chemical vapor deposition at the substrate temperature of 500 and 750°C. The photoconductivity measurements, performed under white light and monochromatic radiation in the ultraviolet–visible–near infrared region, show that the highly defective sample grown at 500°C has a higher photosensitivity, thus revealing the crucial role of structural defects in determining the overall photoresponse of the nanotube’s sheets. The spectral photoresponse of these nanostructured films increases with the increase in photon energy, and is strongly correlated to the absorbance. The photoconductivity properties of these materials are favorable in potential development of large area light sensors as well as optoelectronic nanodevices.

Carbon Nanotubes-Based Radiation Detectors

“…Furthermore, as it is evident from what reported in figure 3, the trend of the device efficiency is in agreement with the absorbance characteristics of MWCNTs constituting the sensitive material in the device. Other experiments have confirmed this behaviour by employing both coherent and non-coherent light sources in pulsed as well as continuous illumination regimes (Passacantando et al, 2008;Coscia et al, 2009). In these experiments, the absence of any photo-electrical response from the substrate guarantees that the signals observed are only due to the nanotube layer.…”

Development of new photon detection device for Cherenkov and fluorescence radiation

“…CNs are grown in the black area around electrodes. As silicon substrate we used 500 mm thick n-doped silicon substrates 5 × 7.8 mm 2 sized with an average carrier concentration of 10 14 cm −3 , covered on both its faces by a 140 nm silicon nitride (Si 3 N 4 ) layer. The drain voltage is applied between the electrodes of the top side and the electrode on the back (Fig.…”

“…Some MWCNT properties made them an attractive material for UV photodetector [1,2] and photosensor applications, when associated their response to light stimulus. We present a novel large area photodetector featuring low noise, good efficiency in the wavelength range from 200 to 1000 nm and great surface uniformity.…”

Progress in the realization of a silicon-CNT photodetector

“…Being the substrate identical on the two cases, this plot demonstrates also the contribution of CNTs to the photon detection and the conversion. On the other hand a significant increase of MWCNT absorbance in the UV region has been observed [5,6]. This result opens the door to a larger use of Si-CNT detectors and suggests the investigation at higher CVD temperatures.…”