Investigation of electronic transport under mechanical strain in a molecular junction composed of a polyyne bridge connected to SWCNT electrodes

Abstract

In the present work we propose a novel treatment to investigate ballistic electron transport under mechanical strain in a 1-D molecular bridge composed of alternating simple and triple bonds (polyyne) connected between two Single-Wall Carbon Nanotube (SWCNT) electrodes. Calculations with the DFT-NEGF methodology were performed in order to analyze this system at low values of mechanical strain (compression and distension) and at equilibrium length in the presence of bias voltages applied along the longitudinal direction. The results show that, while the mechanical strain displaces the energy levels and changes the band gap in the nanotube caps, the applied bias breaks the degeneracy in the nanotube cap states and defines the electrical conductance along the system. The analysis of the PDOS suggests that the main contribution to the electrical current comes from the superposition of the nanotube cap states, which is in agreement with the transmission calculation, and this device can be employed as a transistor observed in the I-V curve.

Molecular junction by tunneling in 1D and quasi-1D systems

“…In other words, the central [Na] atom significantly affects the electron transport properties of the junction. This is concordant with the results obtained by Corrêa et al [6].…”

“…The self energy incorporates the interaction between an electrode and the central region. Γ L/R is the level width function for the left/right electrode, defined as [6]. In addition, we analyze the density of states (DOS), formally defined by…”

“…For a molecular junction with an inorganic electrode, a nitrogen or sulfur anchoring atom is usually used in order to enhance the coupling between the electrode and the central molecule [4]. Alternatively, organic electrodes can also be used, such as metallic carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) [5][6][7][8][9]. Recently two isotropic forms of carbon, namely carbynes and carbon nanotubes (CNTs), have been highlighted in the study of 1D or quasi-1D molecular devices [10][11][12][13][14].…”

“…In this work, we study two systems, a polyyne-Na-polyyne 1D junction and a CNT-Na-CNT quasi-1D junction. Polyyne instead of cumulene is chosen because it is more stable and thus can be produced more easily than cumulene [6,17,18]. Cyclic carbon allotropes consisting of sp-hybridized carbon have been the object interest for years [11].…”

Lateral scaling and positioning effects of top-gate electrodes on single-molecule field-effect transistors

“…The fundamental rule for single molecules working as devices is based on controlling the charge transport properties effectively. One main approach to achieve this goal is through field-effect gating [48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67]. For its higher operation frequency and lower energy consumption, this type of devices becomes a hot topic.…”