Role of electron-phonon interactions and external strain on the electronic properties of semiconducting carbon nanotubes

The electron-phonon interactions determine the temperature dependent photoluminescence of semiconducting carbon nanotubes. Both effects, the energy shifts and spectral narrowing of the transitions, can be attributed to the electron-phonon interaction. In this paper, we present an accurate measurement of the temperature induced broadening of the photoluminescence transitions of carbon nanotubes, and model this broadening in terms of the theory, previously used to model the thermal broadening of critical points in conventional semiconductors. Through this fitting procedure, parameters could be estimated which provide important insight into the strength of the electron-phonon interactions. Moreover, careful studies of the energy shifts induced by the external strain had revealed a n-m family behavior. We further conclude that using a mathematical expression that combines the theory of semiconducting carbon nanotubes under hydrostatic pressure and strain, this family behavior observed experimentally could be theoretically reproduced, providing tools to model and predict the effect of strain on the electronic properties of carbon nanotubes.