@article{zheng_lu_abtew_meunier_bernholc_2010, title={Negative Differential Resistance in C60-Based Electronic Devices}, volume={4}, ISSN={1936-0851 1936-086X}, url={http://dx.doi.org/10.1021/nn101902r}, DOI={10.1021/nn101902r}, abstractNote={Unlike single-C(60)-based devices, molecular assemblies based on two or more appropriately connected C(60) molecules have the potential to exhibit negative differential resistance (NDR). In this work, we evaluate electron transport properties of molecular devices built from two C(60) molecules connected by an alkane chain, using a nonequilibrium Green function technique implemented within the framework of density functional theory. We find that electronic conduction in these systems is mediated by the lowest unoccupied molecular orbitals (LUMOs) of C(60), as in the case of a single-C(60)-based device. However, as the positions of the LUMOs are pinned to the chemical potentials of their respective electrodes, their relative alignment shifts with applied bias and leads to a NDR at a very low bias. Furthermore, the position and magnitude of the NDR can be tuned by chemical modification of the C(60) molecules. The role of the attached molecules is to shift the LUMO position and break the symmetry between the forward and reverse currents. The NDR feature can also be controlled by changing the length of the alkane linker. The flexibility and richness of C(60)-based molecular electronics components point to a potentially promising route for the design of molecular devices and chemical sensors.}, number={12}, journal={ACS Nano}, publisher={American Chemical Society (ACS)}, author={Zheng, Xiaohong and Lu, Wenchang and Abtew, Tesfaye A. and Meunier, Vincent and Bernholc, Jerry}, year={2010}, month={Nov}, pages={7205–7210} }
 @article{abtew_zhang_pan_drabold_2008, title={Electrical conductivity and Meyer-Neldel rule: The role of localized states in hydrogenated amorphous silicon}, volume={354}, ISSN={["1873-4812"]}, DOI={10.1016/j.jnoncrysol.2007.09.103}, abstractNote={The Meyer–Neldel rule (MNR) has been observed in recent calculations of the electrical conductivity of hydrogenated amorphous silicon. To elucidate the origin of this effect, we have performed comparative studies on crystalline Si and non-hydrogenated a-Si. We find that the MNR is not present in the crystal, and is present in a-Si. This suggests that the existence of localized states and the energy dependence of the electron-lattice coupling for these states is an essential feature of the MNR for amorphous phases of silicon.}, number={19-25}, journal={JOURNAL OF NON-CRYSTALLINE SOLIDS}, author={Abtew, T. A. and Zhang, MingLiang and Pan, Yue and Drabold, D. A.}, year={2008}, month={May}, pages={2909–2913} }