Acoustoelectric Effect in Fluorinated Carbon Nanotube in the Absence of External Electric Field

Abstract

Acoustoelectric effect (AE) in a non-degenerate Fluorine modified single walled carbon nanotube (FSWCNT) semiconductor is studied theoretically using the Boltzmann's transport equation. The study is done in the hypersound regime i.e. 1 q  , where q is the acoustic phonon wavenumber and  is the electron mean free path. The results obtained are compared with that of undoped single walled carbon nanotube (SWCNT). The AE current density for FSWCNT is observed to be four orders of magnitude smaller than that of undoped SWCNT with increasing temperature, that is FSWCNT SWCNT z z j j . This is because the electron-phonon interactions in SWCNT are stronger than FSWCNT. Thus, there are more intra-mini-band electrons interacting with the acoustic phonons to generate a higher AE current in SWCNT than in FSWCNT. This has been observed experimentally, where the electrical resistance of FSWCNT is higher than pristine SWCNT i.e. 20 M R Ω . The study shows the potential for FSWCNT as an ultrasound current source density imaging (UCSDI) and AE hydrophone material. However, FSWCNT offers the potential for room temperature applications of acoustoelectric device but other techniques are needed to reduce the resistance.

Semiconductor Fluorinated Carbon Nanotube as a Low Voltage Current Amplifier Acoustic Device

“…) can be solved explicitly under two conditions: 1) in the absence of an electric field when 12 there is no absorption of acoustic waves and thus no AE current present. The FSWCNT under such a condition can be used as a current filter and this phenomenon has been observed in[14]. 2) In the presence of a weak field 1 ωτ  , we obtain Equation(23) which shows a strong nonlinear dependence of AE to a maximum, and falls off in a manner similar to that observed in negative differential conductivity (NDC)[4] [21]-[26] as shownFigure 3, when 1d s v v  [2] [3] [4].…”

“…where [14] and employing a tractable analytical approach, we assume that the sound flux and the external electric field are along the FSWCNT axis (z-axis). The AE current density can then be written as:…”

“…Substituting Equation (14) and Equation (15) into Equation (10), we obtain an equation for AE z j as:…”

“…For most of the conduction electrons, this component of velocity will be much larger in magnitude than the speed of the acoustic wave, so that these electrons are "out of phase" in relation to the propagating electric field, thus creating the so-called acoustoelectric effect (AE) [4] acoustomagnetoelectric effect [12], acoustothermal effect [13] and acoustomagnetothermal effect [13]. Recently, AE was studied in semiconductor fluorinated carbon nanotube (FSWCNT) with double periodic band in the absence of an external electric field [14].…”

Induced Hall-Like Current by Acoustic Phonons in Semiconductor Fluorinated Carbon Nanotube

“…In n-type semiconductors, these electrons are in the conduction band. This process of generating an electric current by the travelling acoustic wave is known as the acoustoelectric effect (AE) in the case of an open circuit or a constant electric field [1] [2] [3] [4].…”