More Like this

1. Atomic Layer Deposition of Nanolayered Carbon Films

   https://doi.org/10.3390/c7040067  

   Xiao, Zhigang; Kisslinger, Kim; Monikandan, Rebhadevi (December 2021, C)

   In this paper, carbon thin films were grown using the plasma-enhanced atomic layer deposition (PE-ALD). Methane (CH4) was used as the carbon precursor to grow the carbon thin film. The grown film was analyzed by the high-resolution transmission electron micrograph (TEM), X-ray photoelectron spectroscopy (XPS) analysis, and Raman spectrum analysis. The analyses show that the PE-ALD-grown carbon film has an amorphous structure. It was found that the existence of defective sites (nanoscale holes or cracks) on the substrate of copper foil could facilitate the formation of nanolayered carbon films. The mechanism for the formation of nanolayered carbon film in the nanoscale holes was discussed. This finding could be used for the controlled growth of nanolayered carbon films or other two-dimensional nanomaterials while combining with modern nanopatterning techniques. 

   more » « less
2. Large-area photonic lift-off process for flexible thin-film transistors

   https://doi.org/10.1038/s41528-022-00145-z  

   Weidling, Adam_M; Turkani, Vikram_S; Akhavan, Vahid; Schroder, Kurt_A; Swisher, Sarah_L (February 2022, npj Flexible Electronics)

   Abstract Fabricating flexible electronics on plastic is often limited by the poor dimensional stability of polymer substrates. To mitigate, glass carriers are used during fabrication, but removing the plastic substrate from a carrier without damaging the electronics remains challenging. Here we utilize a large-area, high-throughput photonic lift-off (PLO) process to rapidly separate polymer films from rigid carriers. PLO uses a 150 µs pulse of broadband light from flashlamps to lift-off functional thin films from glass carrier substrates coated with a light absorber layer (LAL). Modeling indicates that the polymer/LAL interface reaches above 800 °C during PLO, but the top surface of the PI remains below 120 °C. An array of indium zinc oxide (IZO) thin-film transistors (TFTs) was fabricated on a polyimide substrate and photonically lifted off from the glass carrier. The TFT mobility was unchanged by PLO. The flexible TFTs were mechanically robust, with no reduction in mobility while flexed. 

   more » « less
3. Growth of nanostructured molybdenum disulfide (MoS2) thin films on a nanohole-patterned substrate using plasma-enhanced atomic layer deposition (ALD)

   https://doi.org/10.1063/5.0153256  

   Xiao, Zhigang; Doerk, Gregory; Kisslinger, Kim; Jones, Abram; Monikandan, Rebhadevi (May 2023, AIP Advances)

   Nanostructured molybdenum disulfide (MoS2) thin films were grown on a nanohole-patterned silicon substrate using plasma-enhanced atomic layer deposition. A nanoscale hole-patterned silicon substrate was fabricated for the growth of MoS2 film using the self-assembly-based nanofabrication method. The nanoscale holes can significantly increase the surface area of the substrate while the formation and growth of nanostructures normally start at the surface of the substrate. Hydrogen sulfide (H2S) gas was used as the S source in the growth of molybdenum disulfide (MoS2) while molybdenum (V) chloride (MoCl5) powder was used as the Mo source. The MoS2 film had a stoichiometric ratio of 1 (Mo) to 2 (S), and had peaks of E12g and A1g, which represent the in-plane and out-plane vibration modes of the Mo–S bond, respectively. It was found that the MoS2 film grown in the nanoscale hole, especially at the wall of the hole, has more hexagonal-like structures due to the effects of nanoscale space confinement and the nanoscale interface although the film shows an amorphous structure. Post-growth high-temperature annealing ranging from 800 to 900 °C produced local crystalline structures in the film, which are compatible with those reported by other researchers. 

   more » « less
4. Effects of elevated-temperature deposition on the atomic structure of amorphous Ta2O5 films

   https://doi.org/10.1063/5.0170100  

    Prasai, K.; Lee, K.; Baloukas, B.;  Cheng, H-P; Fazio, M.; Martinu, L.; Mehta, A.; Menoni, C_S; Schiettekatte, F.; Shink, R.; et al (December 2023, APL Materials)

   Brownian thermal noise as a result of mechanical loss in optical coatings will become the dominant source of noise at the most sensitive frequencies of ground-based gravitational-wave detectors. Experiments found, however, that a candidate material, amorphous Ta2O5, is unable to form an ultrastable glass and, consequently, to yield a film with significantly reduced mechanical loss through elevated-temperature deposition alone. X-ray scattering PDF measurements are carried out on films deposited and subsequently annealed at various temperatures. Inverse atomic modeling is used to analyze the short and medium range features in the atomic structure of these films. Furthermore, in silico deposition simulations of Ta2O5 are carried out at various substrate temperatures and an atomic level analysis of the growth at high temperatures is presented. It is observed that upon elevated-temperature deposition, short range features remain identical, whereas medium range order increases. After annealing, however, both the short and medium range orders of films deposited at different substrate temperatures are nearly identical. A discussion on the surface diffusion and glass transition temperatures indicates that future pursuits of ultrastable low-mechanical-loss films through elevated temperature deposition should focus on materials with a high surface mobility, and/or lower glass transition temperatures in the range of achievable deposition temperatueres. 

   more » « less
5. A flexible thin film lithium battery with a chemical vapor deposited organic complex cathode

   https://doi.org/10.1039/D1TA10867K  

   Li, Zhuo; Hu, Fei; Huo, Ni; Tenhaeff, Wyatt E. (March 2022, Journal of Materials Chemistry A)

   Organic cathode materials have attracted significant research attention recently, yet their low electronic conductivity limits their application as solid-state cathodes in lithium batteries. This work describes the development of a novel organic cathode chemistry with significant intrinsic electronic conductivity for solid-state thin film batteries. A polymeric charge transfer complex (CTC) cathode, poly(4-vinylpyridine)-iodine monochloride (P4VP·ICl), was prepared by initiated chemical vapor deposition (iCVD). Critical chemical, physical, and electrochemical properties of the CTC complex were characterized. The complex was found to have an electronic conductivity of 4 × 10-7 S cm-1 and total conductivity of 2 × 10−6 S cm−1 at room temperature, which allows the construction of a 2.7 μm thick dense cathode. By fabricating a P4VP·ICl|LIPON|Li thin film battery, the discharge capacity of P4VP·ICl was demonstrated to be >320 mA h cm−3 on both rigid and flexible substrates. The flexible P4VP·ICl|LIPON|Li battery was prepared by simply replacing the rigid substrate with a flexible polyimide substrate and the as-prepared battery can be bent 180° while maintaining electrochemical performance. 

   more » « less