Wafer-Scale Fabrication of Separated Carbon Nanotube Thin-Film Transistors for Display Applications

Abstract

Preseparated, semiconductive enriched carbon nanotubes hold great potential for thin-film transistors and display applications due to their high mobility, high percentage of semiconductive nanotubes, and room-temperature processing compatibility. Here in this paper, we report our progress on wafer-scale processing of separated nanotube thin-film transistors (SN-TFTs) for display applications, including key technology components such as wafer-scale assembly of high-density, uniform separated nanotube networks, high-yield fabrication of devices with superior performance, and demonstration of organic light-emitting diode (OLED) switching controlled by a SN-TFT. On the basis of separated nanotubes with 95% semiconductive nanotubes, we have achieved solution-based assembly of separated nanotube thin films on complete 3 in. Si/SiO₂ wafers, and further carried out wafer-scale fabrication to produce transistors with high yield (>98%), small sheet resistance (∼25 kΩ/sq), high current density (∼10 μA/μm), and superior mobility (∼52 cm² V⁻¹ s⁻¹). Moreover, on/off ratios of >10⁴ are achieved in devices with channel length <i>L</i> > 20 μm. In addition, OLED control circuit has been demonstrated with the SN-TFT, and the modulation in the output light intensity exceeds 10⁴. Our approach can be easily scaled to large areas and could serve as critical foundation for future nanotube-based display electronics.