Additive Influence of Top Metal Contact and Alumina Deposition on the Threshold Voltage of Suspended Carbon Nanotube Field-Effect Transistors

One-dimensional nanostructures such as carbon nanotubesoffer excellentproperties useful for applications in gas sensors, piezoresistivedevices, and radio frequency resonators. Considering their nanoscaleform factor, carbon nanotubes (CNTs) are highly sensitive to surfaceadsorbents. This study presents the fabrication flow of CNT deviceswith extended passivated areas around electrical contacts betweenthe CNT and source and drain electrodes. These types of structurescould help in understanding the intrinsic CNT response by eliminatingthe analyte impact on the Schottky barrier regions of the CNT field-effecttransistors (CNTFETs). The influence of multiple processing conditionson the electronic properties of CNTFETs with a suspended individualCNT used as the CNTFET channel is presented. Our findings show a thresholdvoltage shift in CNT I (SD)-V (g) characteristics following the metal depositionand alumina atomic layer deposition.