Staff directory Aleandro Antidormi

Publications

2021

  • Advanced Data Encryption ​using 2D Materials

    Wen C., Li X., Zanotti T., Puglisi F.M., Shi Y., Saiz F., Antidormi A., Roche S., Zheng W., Liang X., Hu J., Duhm S., Roldan J.B., Wu T., Chen V., Pop E., Garrido B., Zhu K., Hui F., Lanza M. Advanced Materials; 33 (27, 2100185) 2021. 10.1002/adma.202100185. IF: 30.849

    Advanced data encryption requires the use of true random number generators (TRNGs) to produce unpredictable sequences of bits. TRNG circuits with high degree of randomness and low power consumption may be fabricated by using the random telegraph noise (RTN) current signals produced by polarized metal/insulator/metal (MIM) devices as entropy source. However, the RTN signals produced by MIM devices made of traditional insulators, i.e., transition metal oxides like HfO2 and Al2O3, are not stable enough due to the formation and lateral expansion of defect clusters, resulting in undesired current fluctuations and the disappearance of the RTN effect. Here, the fabrication of highly stable TRNG circuits with low power consumption, high degree of randomness (even for a long string of 224 − 1 bits), and high throughput of 1 Mbit s−1 by using MIM devices made of multilayer hexagonal boron nitride (h-BN) is shown. Their application is also demonstrated to produce one-time passwords, which is ideal for the internet-of-everything. The superior stability of the h-BN-based TRNG is related to the presence of few-atoms-wide defects embedded within the layered and crystalline structure of the h-BN stack, which produces a confinement effect that avoids their lateral expansion and results in stable operation. © 2021 Wiley-VCH GmbH.


  • Emerging properties of non-crystalline phases of graphene and boron nitride based materials

    Antidormi A., Colombo L., Roche S. Nano Materials Science; 2021. 10.1016/j.nanoms.2021.03.003. IF: 0.000

    We review recent developments on the synthesis and properties of two-dimensional materials which, although being mainly of an sp2 bonding character, exhibit highly disordered, non-uniform and structurally random morphologies. The emergence of such class of amorphous materials, including amorphous graphene and boron nitride, have shown superior properties compared to their crystalline counterparts when used as interfacial films. In this paper we discuss their structural, vibrational and electronic properties and present a perspective of their use for electronic applications. © 2021 Chongqing University


  • Optimizing the Photothermoelectric Effect in Graphene

    Antidormi A., Cummings A.W. Physical Review Applied; 15 (5, 054049) 2021. 10.1103/PhysRevApplied.15.054049. IF: 4.985

    Among its many uses, graphene shows significant promise for optical and optoelectronic applications. In particular, devices based on the photothermoelectric effect (PTE) in graphene can offer a strong and fast photoresponse with a high signal-to-noise ratio while consuming minimal power. In this work, we discuss how to optimize the performance of graphene PTE photodetectors by tuning the light confinement, device geometry, and material quality. This study should prove useful for the design of devices using the PTE in graphene, with applications including optical sensing, data communications, multigas sensing, and others. © 2021 American Physical Society.


  • Strong Suppression of Thermal Conductivity in the Presence of Long Terminal Alkyl Chains in Low-Disorder Molecular Semiconductors

    Selezneva E., Vercouter A., Schweicher G., Lemaur V., Broch K., Antidormi A., Takimiya K., Coropceanu V., Brédas J.-L., Melis C., Cornil J., Sirringhaus H. Advanced Materials; 33 (37, 2008708) 2021. 10.1002/adma.202008708. IF: 30.849

    While the charge transport properties of organic semiconductors have been extensively studied over the recent years, the field of organics-based thermoelectrics is still limited by a lack of experimental data on thermal transport and of understanding of the associated structure–property relationships. To fill this gap, a comprehensive experimental and theoretical investigation of the lattice thermal conductivity in polycrystalline thin films of dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (Cn-DNTT-Cn with n = 0, 8) semiconductors is reported. Strikingly, thermal conductivity appears to be much more isotropic than charge transport, which is confined to the 2D molecular layers. A direct comparison between experimental measurements (3ω–Völklein method) and theoretical estimations (approach-to-equilibrium molecular dynamics (AEMD) method) indicates that the in-plane thermal conductivity is strongly reduced in the presence of the long terminal alkyl chains. This evolution can be rationalized by the strong localization of the intermolecular vibrational modes in C8-DNTT-C8 in comparison to unsubstituted DNTT cores, as evidenced by a vibrational mode analysis. Combined with the enhanced charge transport properties of alkylated DNTT systems, this opens the possibility to decouple electron and phonon transport in these materials, which provides great potential for enhancing the thermoelectric figure of merit ZT. © 2021 The Authors. Advanced Materials published by Wiley-VCH GmbH


  • Thermal conductivity of benzothieno-benzothiophene derivatives at the nanoscale

    Gueye M.N., Vercouter A., Jouclas R., Guérin D., Lemaur V., Schweicher G., Lenfant S., Antidormi A., Geerts Y., Melis C., Cornil J., Vuillaume D. Nanoscale; 13 (6): 3800 - 3807. 2021. 10.1039/d0nr08619c. IF: 7.790

    We study by scanning thermal microscopy the nanoscale thermal conductance of films (40-400 nm thick) of [1]benzothieno[3,2-b][1]benzothiophene (BTBT) and 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT-C8). We demonstrate that the out-of-plane thermal conductivity is significant along the interlayer direction, larger for BTBT (0.63 ± 0.12 W m-1 K-1) compared to C8-BTBT-C8 (0.25 ± 0.13 W m-1 K-1). These results are supported by molecular dynamics calculations (approach to equilibrium molecular dynamics method) performed on the corresponding molecular crystals. The calculations point to significant thermal conductivity (3D-like) values along the 3 crystalline directions, with anisotropy factors between the crystalline directions below 1.8 for BTBT and below 2.8 for C8-BTBT-C8, in deep contrast with the charge transport properties featuring a two-dimensional character for these materials. In agreement with the experiments, the calculations yield larger values in BTBT compared to C8-BTBT-C8 (0.6-1.3 W m-1 K-1versus 0.3-0.7 W m-1 K-1, respectively). The weak thickness dependence of the nanoscale thermal resistance is in agreement with a simple analytical model. This journal is © The Royal Society of Chemistry.


  • 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: 7.103

    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 oxidation morphology on reduced graphene oxides upon thermal annealing

    Aleandro Antidormi, Stephan Roche, Luciano Colombo Journal Of Physics-Materials; 3 (1, 15011) 2020. 10.1088/2515-7639/ab5ef2. IF: 0.000


  • 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.