Enhancement in gating efficiency of single-molecule field-effect transistors by tuning quantum interference

Abstract

Modification on molecular structure is an effective method to enhance the gating performance of a single-molecule field-effect transistor. In this article, the gating efficiency is modulated through substituting heteroatom (O, S and Se) in a five-membered cyclic compound. The result shows that the heteroatom and the connection site have significant effects on the gating performance of a single-molecule field-effect transistor. When the five-membered ring connects to the molecular backbone through C2 and C5 sites, the conductance of transmission eigenchannels locating in the source–drain bias window varies most significantly in furan-based (heteroatom O) device. Then an enhanced ON-state current and a suppressed OFF-state current, as well as a large ON/OFF current ratio (41.5), are observed. While the five-membered ring connects at C2 and C4 sites, destructive quantum interference is introduced into the transmission spectra. Within the gate voltage range studied in this work, the transmission valley of selenophene-based (heteroatom Se) device enters the bias window. Thus a significantly suppressed OFF-state current and an even larger ON/OFF current ratio (355.9) are obtained. These results will provide theoretical direction in future design of single-molecule field-effect transistor with improved gating efficiency by introducing heteroatom.