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Modelling of Charge Transport in Solids


Karl-Franzens-Universität Graz, Dep. of Physics
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Ulrich Hohenester
Walter Pötz

Universita degli Studi di Firenze, Dip. di Matematica Applicata
Dipartimento di Matematica "Ulisse Dini"
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Giovanni Frosali
Luigi Barletti

Universita degli Studi di Catania, DMI
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Armando Majorana
Oracio Muscato
Vittorio Romano
Giovanni Russo

Universita degli Studi di Parma, Dip. di Matematica
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Gian Luca Caraffini
Maria Groppi
Giampiero Spiga


Politecnico di Torino
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Roberto Monaco
Alberto Rossani

UC San Diego, Dep. of Cognitive Science
Claudia Lainscsek

California State University Northridge, Dep. of Mathematics Industriale
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Jacek Polewczak

Current research activities

This page gives a short description of the different research activities, to quickly jump to a specific work use the link list below. If you are interested in a particular topic and would like to know more, please feel invited to contact the person(s) listed with this topic.
Direct Simulation of Quantum Transport in Semiconductors
Omar Morandi
Antonius Dorda
Ferdinand Schürrer

The development of efficient quantum computational methods is a crucial aspect in the development of the new generation devices where the size of the charge confinement becomes comparable to the electron wavelength. We are interested in studying semiconductors where the heterostructure design induces coherent interference effects between different bands. We will investigate the contribution of interband current in a Resonant Interband Tunneling Diode by means of a multi-band Wigner transport model. Furthermore we will apply multiband quantum kinetic model to study high field effects in carbon nanotubes and in graphene structures. Graphene is an interesting material for future device applications not only because of its greatly enhanced mobility compared to traditional transistor materials but especially due to its unique band structure. In the proximity of the Fermi energy, the bands are well described by a biconical shape, resembling the dispersion relation of mass less Dirac fermions and thus resulting in unusual effects like the Klein paradox. Since graphene is essentially a zero band gap material, interband tunneling plays a crucial role. Therefore, a full quantum mechanical treatment has to be carried out. This is done in the framework of the Wigner function formalism. In this work, two different cases are examined: On the one hand, the full non-local time evolution equations for the Wigner function to study Klein tunneling and on the other hand, in the limit of larger device dimensions (submicrometer) and slowly varying electric fields, a set of approximate equations of motion is considered. The latter is in close analogy to its semi-classical counterpart with extra terms incorporating the quantum mechanical corrections.

FWF project No. P21326-N16
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Charge carrier transport in organic thin-film transistors
Manfred Gruber
Karin Zojer
Ferdinand Schürrer
Current distribution in an organic thin-film transistor
By means of a two-dimensional drift-diffusion approach we investigate the principle mechanisms which influence the shape of the I-V characteristic of top-contact bottom-gate pentacene thin-film transistors. Recent calculations deal with the charge carrier injection mechanisms present at the contacts, the formation of a hysteresis in the transfer characteristic due to trapping and detrapping of charge carriers, and the influence of light.

NILAustria - Project NILsimtos
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Investigation of the impact of built-in electric fields on the efficiency of nanocomposite solar cells
Iris Hehn
Karin Zojer
Ferdinand Schürrer

The aim of this work is to study the impact of built-in electric fields on the carrier transport and the efficiency of nanocomposite solar cells by means of numerical modeling. A two-dimensional drift-diffusion model is used to describe carrier transport in the devices. Novel strategies will be tested to incorporate electric fields due to charge rearrangements at metal-semiconductor or semiconductor-semiconductor interfaces into the model. The such developed model will be used to quantitatively study the device efficiency as a function of origin, position, and extent of such electric fields.

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