1. A thin film transistor comprising: a source electrode; a drain electrode spaced from the source electrode; a semiconductor layer; a channel comprising a plurality of carbon nanotube wires, one end of each carbon nanotube wire is connected to the source electrode, and opposite end of each the carbon nanotube wire is connected to the drain electrode; and a gate electrode insulated from the source electrode, the drain electrode, and the semiconducting layer by an insulating layer.