Electronic Band Structure Mapping of Nanotube Transistors by Scanning Photocurrent Microscopy

TL;DR

This paper demonstrates that scanning photocurrent microscopy can effectively map the electronic band structure and Schottky barrier height of carbon nanotube transistors, revealing doping effects and transport regimes.

Contribution

It introduces a method to spatially resolve the electronic band structure of nanotube transistors using photocurrent measurements, providing new insights into device doping and barriers.

Findings

Photocurrent profiles reveal the band structure of nanotube transistors.

Doping effects are clearly observed in different biasing conditions.

Schottky barrier height can be quantitatively determined using this technique.

Abstract

Spatially resolved photocurrent measurements on carbon nanotube field-effect transistors (CNFETs) operated in various transport regimes are reported. It is demonstrated that the photocurrents measured at different biasing conditions provide access to the electronic band structure profile of the nanotube channel. A comparison of the profiles with the device switched into n- or p-type states clearly evidences the impact of chemical doping from the ambient. Moreover, we show that scanning photocurrent microscopy constitutes an effective and facile technique for the quantitative determination of the Schottky barrier height in such devices.