We report the excited-state electron dynamics for ultrathin films of NaCl on Ag(100). The first three image potential states (IPSs) were initially observed following excitation. The electrons in the spatially delocalized n = 1 IPS decayed on the ultrafast time scale into multiple spatially localized states lower in energy. The localized electronic states are proposed to correspond to electrons trapped at defects in the NaCl islands. Coverage and temperature dependence of the localized states support the assignment to surface trap states existing at the NaCl/vacuum interface. These results highlight the importance of electron trapping in ultrathin insulating layers.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1021/jz501572z | DOI Listing |
ACS Appl Mater Interfaces
January 2025
Instituto de Ciencia de Materiales de Barcelona (ICMAB-CSIC), Campus UAB, Carrer dels Til·lers, s/n, Bellaterra, 08193 Barcelona, Spain.
The influence of the film/substrate interface and the role of film thickness on the structural transition temperature for thin films of the asymmetric BTBT derivative 7-decyl-2-phenyl[1]benzothieno[3,2-][1]-benzothiophene (Ph-BTBT-10) have been addressed by using Kelvin probe force microscopy (KPFM) and synchrotron grazing incidence wide angle X-ray scattering (GIWAXS). Our data strongly suggest that the structural transformation from a single-layer phase to the thermodynamically stable bilayer structure develops from the bottom of the film to its surface. Contrary to observations in other organic semiconductor films, notably, the thinner the Ph-BTBT-10 film, the lower is the transition temperature.
View Article and Find Full Text PDFACS Nano
January 2025
School of Environmental and Life Sciences, The University of Newcastle, Callaghan, New South Wales 2308, Australia.
Fullerenes, with well-defined molecular structures and high scalability, hold promise as fundamental building blocks for creating a variety of carbon materials. The fabrication and transfer of large-area films with precisely controlled thicknesses and morphologies on desired surfaces are crucial for designing and developing fullerene-based materials and devices. In this work, we present strategies for solid-state transferring C molecular nanometer-thin films, with dimensions of centimeters in lateral size and thicknesses controlled in the range of 1-20 nm, onto various substrates.
View Article and Find Full Text PDFScience
January 2025
Department of Electrical Engineering, Stanford University, Stanford, CA, USA.
The electrical resistivity of conventional metals such as copper is known to increase in thin films as a result of electron-surface scattering, thus limiting the performance of metals in nanoscale electronics. Here, we find an unusual reduction of resistivity with decreasing film thickness in niobium phosphide (NbP) semimetal deposited at relatively low temperatures of 400°C. In films thinner than 5 nanometers, the room temperature resistivity (~34 microhm centimeters for 1.
View Article and Find Full Text PDFSci Adv
January 2025
Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA.
We report the appearance of superconductivity in single-unit-cell NdNiO, exhibiting a transition temperature similar to that of thicker films. In situ synchrotron x-ray scattering performed during growth of the parent phase, NdNiO, shows that the necessary layer-by-layer deposition sequence does not follow the sequence of the formula unit but an alternate order due to the relative stability of the perovskite unit cell. We exploit this insight to grow ultrathin NdNiO heterostructures and conduct in situ studies of topotactic reduction, finding that formation of the square-planar phase occurs rapidly and is highly sensitive to reduction temperature, with small deviations from the optimum condition leading to inhomogeneity and the loss of superconductivity.
View Article and Find Full Text PDFAdv Mater
December 2024
Institute of Physics (IA), RWTH Aachen University, Sommerfeldstraße 14, 52074, Aachen, Germany.
A systematic study of the impact of film thickness on the properties of thin Bi films is presented. To this end, epitaxial films of high quality have been grown on a Si (111) substrate with thicknesses ranging from 1.9 to 29.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!