Measuring Carbon Nanotube Band Gaps through Leakage Current and Excitonic Transitions of Nanotube Diodes

Abstract

The band gap of a semiconductor is one of its most fundamental properties. It is one of the defining parameters for applications, including nanoelectronic and nanophotonic devices. Measuring the band gap, however, has received little attention for quasi-one-dimensional materials, including single-walled carbon nanotubes. Here we show that the current-voltage characteristics of p-n diodes fabricated with semiconducting carbon nanotubes can be used along with the excitonic transitions of the nanotubes to measure both the fundamental (intrinsic) and renormalized nanotube band-gaps.

Scanning tunneling spectroscopy of single-wall carbon nanotubes on a polymerized gold substrate

“…The intrinsic electronic band gap of the nanotube should be 1.48 eV according to Eq. (2). With the diameter of 0.9 nm, calculation by either Eq.…”

“…In contrast, the many-body theory gives a very different result [6,[12][13][14][15], predicting an appreciably larger band gap for a semiconductor nanotube than that predicted by the one-particle model [5]. The many-body picture has been verified by plenty of optical experiments to date [2][3][4][5][6]. In this context, the interpretation of STS of carbon nanotubes seems not so simple.…”

“…This is the most straightforward and convenient technique for the characterization of individual nanostructures in comparison with other state-of-the-art methods [1][2][3][4][5][6]. Nonetheless, to date a theoretical description of STS experiments on carbon nanotubes remains a not-well-resolved issue.…”

Split gate and asymmetric contact carbon nanotube optical devices

“…In the case of a p-n junction reverse bias current is due to the diffusion current from minority carriers and/or the generation of electron hole pairs in the junction. An ideality factor of 1 represents a saturation current due to diffusion current and an ideality factor of 2 represents a saturation current due to generation current, if η > 2, this indicates the junction does not behave as an ideal p-n junction [11,37,39]. In symmetrically contacted CNT p-n junctions formed by a split gate Malapanis et al showed that I 0 decreased exponentially with increasing CNT bandgap [11].…”

“…has been used to demonstrate CNT field effect transistor (FET) p-n junction diodes [3,[8][9][10][11]. It can also be used to modify the band profile of CNTs to facilitate EL.…”