Surface-water-assisted deposition of patterned films of aligned nanoparticles

A method of patterning a silicon dioxide surface of a substrate with one or more hydrophilic surface regions bounded by one or more less hydrophilic surface region, the method comprising:

• forming a layer of a resist on the silicon dioxide surface;
• patterning the layer of resist to expose one or more regions of the silicon dioxide surface through the layer of resist;
• depositing a layer of yttrium metal or a layer of scandium metal over the layer of resist and the one or more exposed regions of the silicon dioxide surface to form yttrium metal-coated or scandium metal-coated surface regions on the silicon dioxide surface;
• removing the patterned layer of resist from the silicon dioxide surface;
• oxidizing the yttrium metal or scandium metal on the silicon dioxide surface;
• forming a layer of material having a lower hydrophilicity than the silicon dioxide on the silicon dioxide surface and over the oxidized yttrium or oxidized scandium;
• and
• removing the oxidized yttrium or oxidized scandium from the silicon dioxide surface to form one or more hydrophilic silicon dioxide surface region bounded by the material having the lower hydrophilicity than the silicon dioxide.

A field effect transistor comprising:

• a source electrode;
• a drain electrode;
• a gate electrode;
• and
• a conducting channel in electrical contact with the source electrode and the drain electrode, the conducting channel comprising a film comprising aligned semiconducting single-walled carbon nanotubes, the field effect transistor having a current density of at least 1.8 mA μm−1 and a transconductance of at least 1.14 mS μm−1, as measured at 0.6 V drain voltage.