Graphene on a Hydrophobic Substrate: Doping Reduction and Hysteresis Suppression under Ambient Conditions

• Published in: Nano letters Vol. 10; no. 4; pp. 1149 - 1153
• Main Authors: Lafkioti, Myrsini, Krauss, Benjamin, Lohmann, Timm, Zschieschang, Ute, Klauk, Hagen, Klitzing, Klaus v, Smet, Jurgen H
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 14-04-2010
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties; Materials science; Methods of nanofabrication; Nanolithography; Physics; Self-assembly; Specific materials; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); hexamethyldisilazane; Graphene; hydrophobic; doping; transport properties; self-assembled layer; hysteresis; Transport properties; Adsorption; Lithography; Morphology; Adsorbates; Doping; Template reaction; Silicon; Self-assembled layers; Exfoliation; Hysteresis
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl903162a

The intrinsic doping level of graphene prepared by mechanical exfoliation and standard lithography procedures on thermally oxidized silicon varies significantly and seems to depend strongly on processing details and the substrate morphology. Moreover, transport properties of such graphene devices suffer from hysteretic behavior under ambient conditions. The hysteresis presumably originates from dipolar adsorbates on the substrate or graphene surface. Here, we demonstrate that it is possible to reliably obtain low intrinsic doping levels and to strongly suppress hysteretic behavior even in ambient air by depositing graphene on top of a thin, hydrophobic self-assembled layer of hexamethyldisilazane (HMDS). The HMDS serves as a reproducible template that prevents the adsorption of dipolar substances. It may also screen the influence of substrate deficiencies.