Teil eines Buches,
Optical Spectroscopy of Doped Carbon Nanotubes
10, Kapitel Chapter 13, Seite 191-236. (2019)
DOI: 10.1142/9789813235465_0013
Zusammenfassung
Controlling charges in semiconductors is key for many of the device technologies that enable the modern information and communication age. Doping by chemical or physical means is intended to provide mobile charge carriers which facilitate crucial semiconductor device functionality. This chapter discusses some of the aspects related to the fabrication and optical characterization of reduced or oxidized semiconducting single-wall carbon nanotubes (s-SWCNTs) for the purpose of doping. We focus on redox- and electro-chemical modification to illustrate how far our current understanding allows not only a qualitative but also a quantitative spectroscopic assessment of impurity concentrations. Somewhat surprisingly, we find that commonly used n- or p-doping schemes appear to lead to inhomogeneous carrier distributions with some excess electrons or holes immobilized by deep Coulomb traps. Such carrier localization is believed to be symptomatic of the weak screening and pronounced susceptibility to environmental perturbations of low-dimensional materials such as SWCNTs. These findings may also have broader implications for the fabrication of functional semiconductor devices from nanoscale materials.
