Photoinduced conductivity changes in carbon nanotube transistors

Abstract

Photoinduced conductivity changes in single-walled carbon nanotube transistors have been examined. Low-intensity ultraviolet light significantly reduces the p-channel conductance while simultaneously increasing the n-channel conductance. A combination of optical absorption and electron transport measurements reveals that these changes occur without variations in dopant concentrations. Possible sites of oxygen photodesorption and its implications on the observed electronic properties of nanotubes are considered.

Electronic and vibrational properties of chemically modified single-wall carbon nanotubes

“…63) [287,294]. The absence of a shift in the threshold voltage has been confirmed by a different experiment in which UV photo-irradiation instead of annealing was used to free the nanotubes from oxygen [483].…”

“…Table 7) does not favour a sizeable charge transfer between tube and adsorbate [462]. In addition, no significant changes could be traced in the resonance Raman, optical absorption, and luminescence spectra of SWCNTs after O 2 exposure [482] or O 2 desorption [483]. In this context, it is worth to note that the strong bleaching of the optical transitions and photoluminescence reported for micelle-dispersed SWCNTs at low pH in the presence of oxygen [482] has very recently been identified to originate from covalent sidewall attachment of oxygen molecules under these conditions [484].…”

Photoelectrical Characteristics of a C/CNx Multiwalled Nanotube

“…[3,4,6,12] However, not much attention has been focused on the use of CNTs in photoelectrical devices. The photoconductivities of single-walled CNTs (SWCNTs) have been recently measured under near-IR, [13] UV, [14] and IR-laser illumination. [15] Furthermore, the emission of polarized light has been observed in CNT field-effect transistors.…”

Surface plasmon effects on carbon nanotube field effect transistors

“…2 The switching properties of CNT FETs are generally dominated by the response of the CNT-metal contact region, resulting in a Schottky-barrier transistor instead of a bulk-switching transistor. 4,27 Some studies point to strongest chemical activity on the CNT-metal contact, 11 but others show doping effects of the SWCNT itself 19 or are otherwise contradicting the idea of oxygen modifying the Schottky barrier via the electrode metal work function. 28 Yet, CNT FETs connected with Pd electrodes are shown to have lower effect, if any at all, on the desorption on the CNT-metal interface region.…”

“…[3][4][5] While the direct electron-hole generation is the most desired effect in photoelectronics, another usually even more important and widely studied effect is due to photodesorption of atmospheric molecules. 5,8,10,11 The photodesorption is strongest in the UV range and usually negligible in near-IR. 5 Surface plasmon polaritons (SPPs) are coupled modes of electromagnetic waves and oscillations of free electrons in a metal surface.…”