Picosecond and subpicosecond pulsed laser deposition of Pb thin films

Abstract

Pb thin films were deposited on Nb substrates by means of pulsed laser deposition (PLD) with UV radiation (248 nm), in two different ablation regimes: picosecond (5 ps) and subpicosecond (0.5 ps). Granular films with grain size on the micron scale have been obtained, with no evidence of large droplet formation. All films presented a polycrystalline character with preferential orientation along the (111) crystalline planes. A maximum quantum efficiency (QE) of 7:3 Â 10 À5 (at 266 nm and 7 ns pulse duration) was measured, after laser cleaning, demonstrating good photoemission performance for Pb thin films deposited by ultrashort PLD. Moreover, Pb thin film photocathodes have maintained their QE for days, providing excellent chemical stability and durability. These results suggest that Pb thin films deposited on Nb by ultrashort PLD are a noteworthy alternative for the fabrication of photocathodes for superconductive radio-frequency electron guns. Finally, a comparison with the characteristics of Pb films prepared by ns PLD is illustrated and discussed.

Growth of poly-crystalline Cu films on Y substrates by picosecond pulsed laser deposition for photocathode applications

“…The photoemission performance of the samples was measured in a photodiode cell illustrated in a previous work [17], with the cathode-anode configuration described in Fig. 1.…”

“…In that context, different metals like Pb, Cu, Al, Al-Li, W, Au or Fe have been extensively studied, and their application in implemented photocathode applications has been evaluated [17][18][19][20][21]. From the reported studies, it has been pointed out that yttrium (Y) and magnesium (Mg), due to their superior performance [12][13][14][15]22,23], seem to be the most promising metallic materials for the fabrication of photocathodes.…”

Electrosynthesis of Quasi-Epitaxial Crystals on Liquid Metals

“…In contrast, experiments performed at −1.30 V exhibited X-ray diffraction peaks at 2θ = 31.3, 36.3, 52.3, 62.2, and 65.3°, indexed to the (111), (020), (220), (311), and (222) planes, respectively. The relative intensities of these signals were in accord with the randomly oriented, polycrystalline Pb …”

Morphology and structure of Pb thin films grown on Si(111) by pulsed laser deposition

“…Many techniques have been used for growth of Pb thin films for photocathode applications, such as electroplated deposition, arc deposition, sputtering, evaporation and pulsed laser deposition (PLD) [9][10][11][12][13][14][15][16][17][18][19]. The formation of thin films with different 2 morphology and crystalline structure is of utmost importance for the development in those applications, and there are ongoing experimental investigations into the characterization of these morphologies [7].…”

“…Pb thin films were previously deposited on Nb substrates using ultrafast laser pulses. Granular films with a maximum quantum efficiency of 7.3x10-5 at laser wavelength 266 nm and 7 nanosecond pulse duration were obtained [18]. In this work, we deposited Pb thin films of varying thickness at substrate temperatures 25°C -300°C and using different laser wavelengths and laser energy density (fluence).…”