Self-Aligned Fabrication Process Based on Sacrificial Catalyst for Pd-Contacted Carbon Nanotube Field-Effect Transistors

In this work, we present a novel very simple process to fabricate carbon nanotube field effect transistors (CNTFETs). It is based on chemical vapor deposition (CVD) growth of single-walled carbon nanotubes (SWNTs) using a 'sacrificial' aluminum/nickel catalyst. The SWNTs are grown uniformly across the wafer surface and subsequently contacted with palladium. The silicon substrate is used as back-gate electrode. The process contains neither complicated manipulations of the SWNTs nor multi-step lithography, avoiding the risk of misalignment. The catalyst is called sacrificial because it turns into an insulating layer after process allowing the gate field to penetrate and control the current flow within the SWNTs. The fabricated structures are unipolar PMOS-like CNTFETs with on/off ratios up to 10 000.