Temperature-Dependent Tunneling in Furan Oligomer Single-Molecule Junctions

作者：Haipeng B. Li, Yan-Feng Xi, Ze-Wen Hong, Jingxian Yu, Xiaoxia Li, Wenxia Liu, Lucas Domulevicz, Shan Jin, Xiao‐Shun Zhou, Joshua Hihath · 发表于：ACS Sensors · 年份：2021 · DOI：10.1021/acssensors.0c02278 · 被引用次数：16 · 研究领域：Molecular Junctions and Nanostructures、Quantum and electron transport phenomena、Advancements in Semiconductor Devices and Circuit Design

Two commonly observed charge transport mechanisms in single-molecule junctions are coherent tunneling and incoherent hopping. It has been generally believed that tunneling processes yield temperature-independent conductance behavior and hopping processes exhibit increasing conductance with increasing temperature. However, it has recently been proposed that tunneling can also yield temperature-dependent transport due to the thermal broadening of the Fermi energy of the contacts. In this work, we examine a series of rigid, planar furan oligomers that are free from a rotational internal degree of freedom to examine the temperature dependence of tunneling transport directly over a wide temperature range (78-300 K). Our results demonstrate conductance transition from a temperature-independent regime to a temperature-dependent regime. By examining various hopping and tunneling models and the correlation between the temperature dependence of conductance and molecular orbital energy offset from the Fermi level, we conclude thermally assisted tunneling is the dominant cause for the onset of temperature-dependent conductance in these systems.