An energy-dependent photoemission study on line-shape analysis in determining the absolute coverage of metallic thin films

Abstract

Energy-dependent photoemission was measured to investigate the validity of the analysis of line shape in determining the absolute coverage of atomically flat, metallic thin films. The surface states of two Ag/Au(1 1 1) thin films with carefully controlled coverage of Ag were measured and analysed. Our results confirm that line-shape analysis is a valid procedure; the absolute error associated with this technique is within 0.1 ML, which makes the technique advantageous over other techniques to determine the film coverage. The experimental procedure in our work provides a routine to determine an appropriate photon energy for use in line-shape analysis. Our results indicate that the widely accessible He Iα line is a suitable excitation source to utilize line-shape analysis for confined states in a Ag film.

Precise determination of absolute coverage of thin films by layer-resolved surface states

“…To justify the assumption, we consider two aspects. 18 Upton et al 8 suggested that layer-resolved quantum-well states on Pb/ Si͑111͒ could be analyzed to determine the absolute film thickness. Second, previous workers reported that the photo- Fig.…”

Atomic-layer-resolved bound states in quantum wells analyzed using a pseudopotential approach

“…The amount of deposited Ag was calibrated with the layer-resolved surface state. 11,15 Deposition conditions were controlled with particular care to ensure that the same amount of Ag was deposited each time. Figure 1 shows typical results from photoemission measurements near the center of the surface Brillouin zone of Ag/Au͑111͒.…”

“…The amount of deposited Ag was precisely determined on analyzing the layer-resolved surface state at a small Ag coverage. 11,15 Through counting layer by layer, we determined unequivocally the absolute thickness to which the QWS corresponds.…”

Characterizing the wetting of metallic thin films with angle-resolved photoelectron spectroscopy

“…Silver was evaporated from a Knudsen crucible; its rate of deposition was calibrated with the evolution of the Shockley states on Ag/Cu͑111͒. 8,11,12 To monitor the evolution of the sample surface, we recorded photoemission spectra during sample annealing. Figure 1 shows typical results from well ordered thin films of Ag on Cu͑111͒.…”