Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 65: Transport Properties II (Theory)

HL 65.4: Talk

Wednesday, March 28, 2012, 17:45–18:00, ER 164

Towards a Unifying Framework of AC Quantum Transport for Nanodevices including Scattering — •Diego Kienle — Theoretische Physik I, Universit\"at Bayreuth, 95440 Bayreuth

At present there is a significant need to model and understand dynamic quantum transport in realistic nanoscale devices including non-idealities e.g. due to scattering to ultimately guide the development of novel quantum devices operating at terahertz (THz) frequencies, even exploiting plasmon waves for THz sensing and emission. To step towards this goal, we discuss in this talk a general approach for linear AC quantum transport formulated by means of Non-Equilibrium Green Functions (NEGF) that is able to simultaneously handle the open nature of transport incorporated through self-energies, the complex dielectric environment typical for realistic devices, and most importantly the self-consistent dynamic coupling of the space-dependent AC charge and potential, the latter being essential to capture the plasmonic response of the system. Employing this approach, it is then discussed how scattering due to charged impurity atoms placed along the channel impacts the high-frequency response of nanodevices, specifically their plasmonic THz spectrum by example of a p-type carbon nanotube transistor. It is shown that particularly positively charged impurities cause a severe degradation of the THz plasmon modes, which vanish when the impurity concentration is sufficiently high. In this case, the AC response is solely determined by the single-particle excitation spectrum. [1] D. Kienle and F. Leonard, PRL 103, 026601 (2009). [2] D. Kienle, M. Vaidyanathan, and F. Leonard, PRB 81, 115455 (2010).