Staff directory Aleandro Antidormi

Publications

2021

  • Thermal transport in amorphous graphene with varying structural quality

    Antidormi A., Colombo L., Roche S. 2D Materials; 8 (1, 015028) 2021. 10.1088/2053-1583/abc7f8. IF: 7.140

    The synthesis of wafer-scale two-dimensional amorphous carbon monolayers has been recently demonstrated. This material presents useful properties when integrated as coating of metals, semiconductors or magnetic materials, such as enabling efficient atomic layer deposition and hence fostering the development of ultracompact technologies. Here we propose a characterization of how the structural degree of amorphousness of such carbon membranes could be controlled by the crystal growth temperature. We also identify how energy is dissipated in this material by a systematic analysis of emerging vibrational modes whose localization increases with the loss of spatial symmetries, resulting in a tunable thermal conductivity varying by more than two orders of magnitude. Our simulations provide some recipe to design most suitable 'amorphous graphene' based on the target applications such as ultrathin heat spreaders, energy harvesters or insulating thermal barriers. © 2020 IOP Publishing Ltd.


2020

  • Impact of synthetic conditions on the anisotropic thermal conductivity of poly(3,4-ethylenedioxythiophene) (PEDOT): A molecular dynamics investigation

    Cappai A., Antidormi A., Bosin A., Narducci D., Colombo L., Melis C. Physical Review Materials; 4 (3, 035401) 2020. 10.1103/PhysRevMaterials.4.035401. IF: 3.337

    In this work we study the effect of different synthetic conditions on thermal transport properties of poly(3,4-ethylenedioxythiophene) (PEDOT) by focusing in particular on the role of proton scavengers. To this aim, different PEDOT samples were generated in silico using a novel computational algorithm based on a combination of first-principles density functional theory and classical molecular dynamics simulations. The corresponding thermal conductivities were then estimated using the approach to equilibrium molecular dynamics methodology. The results show that the initial synthetic conditions strongly affect the corresponding thermal conductivities, which display variations up to a factor of ∼2 depending on the proton scavenger. By decomposing the thermal conductivity tensor along the direction of maximum chain alignment and the corresponding perpendicular directions, we attribute the thermal conductivity differences to the variations in the average polymer chain length λave. A dependence of the thermal conductivity with the polydispersity index was finally observed, suggesting a possible role of intercrystallite chains in enhancing thermal transport properties. By means of the Green-Kubo modal analysis, we eventually characterize the vibrational modes involved in PEDOT thermal transport and investigate how they are related to the thermal conductivity values of the samples. © 2020 American Physical Society.


  • Ultralow-dielectric-constant amorphous boron nitride

    Hong S., Lee C.-S., Lee M.-H., Lee Y., Ma K.Y., Kim G., Yoon S.I., Ihm K., Kim K.-J., Shin T.J., Kim S.W., Jeon E.-C., Jeon H., Kim J.-Y., Lee H.-I., Lee Z., Antidormi A., Roche S., Chhowalla M., Shin H.-J., Shin H.S. Nature; 582 (7813): 511 - 514. 2020. 10.1038/s41586-020-2375-9. IF: 42.779

    Decrease in processing speed due to increased resistance and capacitance delay is a major obstacle for the down-scaling of electronics1–3. Minimizing the dimensions of interconnects (metal wires that connect different electronic components on a chip) is crucial for the miniaturization of devices. Interconnects are isolated from each other by non-conducting (dielectric) layers. So far, research has mostly focused on decreasing the resistance of scaled interconnects because integration of dielectrics using low-temperature deposition processes compatible with complementary metal–oxide–semiconductors is technically challenging. Interconnect isolation materials must have low relative dielectric constants (κ values), serve as diffusion barriers against the migration of metal into semiconductors, and be thermally, chemically and mechanically stable. Specifically, the International Roadmap for Devices and Systems recommends4 the development of dielectrics with κ values of less than 2 by 2028. Existing low-κ materials (such as silicon oxide derivatives, organic compounds and aerogels) have κ values greater than 2 and poor thermo-mechanical properties5. Here we report three-nanometre-thick amorphous boron nitride films with ultralow κ values of 1.78 and 1.16 (close to that of air, κ = 1) at operation frequencies of 100 kilohertz and 1 megahertz, respectively. The films are mechanically and electrically robust, with a breakdown strength of 7.3 megavolts per centimetre, which exceeds requirements. Cross-sectional imaging reveals that amorphous boron nitride prevents the diffusion of cobalt atoms into silicon under very harsh conditions, in contrast to reference barriers. Our results demonstrate that amorphous boron nitride has excellent low-κ dielectric characteristics for high-performance electronics. © 2020, The Author(s), under exclusive licence to Springer Nature Limited.