A comparative study of electron transport in benzene molecule covalently bonded to gold and silicon electrodes for pioneering the electron transport properties of silicon quantum dot-molecule hybrid polymers

• Published in: Current applied physics Vol. 15; no. 8; pp. 877 - 884
• Main Authors: Choi, Jin-Kyu, Pham, Hien Thu, Jeong, Hyun-Dam
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2015; 한국물리학회
• Subjects: DFT; Electrode; Electron transport; NEGF; Semiconductor; Silicon; 물리학; Semiconductor; NEGF; Silicon; Electrode; DFT; Electron transport
• ISSN: 1567-1739; 1878-1675
• DOI: 10.1016/j.cap.2015.03.021

In order to pioneer the electron transport properties of silicon (Si) quantum dot-molecule hybrid polymers, we investigate the electron transport properties of the benzene molecule in silicon (Si) semiconductor electrodes, based on nonequilibrium Green's function (NEGF) method coupled with density functional theory (DFT), in comparison with conventional gold (Au) metal electrodes, with three different anchoring linker groups: thiol for dithiol-benzene (DTB), methylene for dimethyl-benzene (DMB), and direct bonding for benzene (Ph). It is interestingly found that, due to band gap nature of the Si semiconductor electrodes, the molecular junctions with the Si electrodes show no current up to the bias voltage of around 0.8 V. In addition, the DTB molecular junctions in the Si semiconductor electrodes connected with Si–S bond show higher conducting properties than other DMB and Ph molecular junctions directly coupled to the electrodes with the Si–C bonds (DMB < Ph < DTB). The electron transport properties of the molecules in the two different electrodes are analyzed on the basis of the understanding transmission spectra, projected density of states (PDOS), and molecular orbitals. We believe that the use of thiol linker may open new possibility in the molecular electronics with the Si semiconductor electrodes and the Si QD-molecule hybrid polymers concept. [Display omitted] •Molecular junctions with Si electrode were investigated, pioneering Si QD polymers.•Electron transport with Si electrode were studied, in comparison with Au electrode.•Electron transport with Si electrode is much lowered due to semiconducting structure.•Thiol was found to be a good linker even for Si electrode, with Si–S bond.