Chemical gating of In2O3 nanowires by organic and biomolecules

${\mathrm{In}}_2{\mathrm{O}}_3$ nanowire transistors were used to investigate the chemical gating effect of organic molecules and biomolecules with amino or nitro groups. The nanowire conductance changed dramatically after adsorption of these molecules. Specifically, amino groups in organic molecules such as butylamine, donated electrons to ${\mathrm{In}}_2{\mathrm{O}}_3$ nanowires and thus led to enhanced carrier concentrations and conductance, whereas molecules with nitro groups such as butyl nitrite made ${\mathrm{In}}_2{\mathrm{O}}_3$ nanowires less conductive by withdrawing electrons. In addition, intrananowire junctions created by partial exposure of the nanowire device to butyl nitrite were investigated, and pronounced rectifying current–voltage characteristics were obtained. Furthermore, chemical gating by low-density lipoprotein cholesterol, the offending agent in coronary heart diseases, was also observed and attributed to the amino groups carried by the bio species.