Phonon populations in a biased carbon nanotube transistor

We present a comprehensive picture of the phonon populations in an electrically-driven carbon nanotube transistor, including the Raman-active G and radial breathing modes (RBM), and also the Raman-inactive zone boundary mode (K), and intermediate-frequency mode (IFP), populated by anharmonic decay. The effective temperature of the RBM is considerably lower than the intermediate- and high-frequency mode temperatures, which we explain by a phonon-decay bottleneck. We include substrate polar phonon scattering to fully account for the device electronic characteristics.