LaB6 thin films were deposited at a temperature of 500 °C under vacuum or Ar atmosphere by the pulsed laser deposition technique on (100) Si substrates using a KrF laser. Grazing incidence x-ray diffraction investigations found that films were nanocrystalline, with grain size dimensions from 86 to 102 nm and exhibited microstrain values around 1.1%. Simulations of the x-ray reflectivity curves acquired from the deposited films showed that films had a density around 4.55 g/cm3, and were very smooth, with a surface roughness root-mean-square of 1.5 nm, which was also confirmed by scanning electron and atomic force microscopy measurements. All films were covered by a ∼2 nm thick contamination layer that formed when samples were exposed to the ambient. Auger electron spectroscopy investigations found very low oxygen impurity levels below 1.5 at. % once the contamination surface layer was removed by Ar ion sputtering. Four point probe measurements showed that films were conductive, with a resistivity value around 200 μΩ cm for those deposited under Ar atmosphere and slightly higher for those deposited under vacuum. Nanoindentation and scratch investigations showed that films were rather hard, H ∼ 16 GPa, E ∼ 165 GPa, and adherent to the substrate. Thermionic emission measurements indicated a work function value of 2.66 eV, very similar to other reported values for LaB6.
Characteristics of LaB6 thin films grown by pulsed laser deposition
Valentin Craciun, Daniel Cristea, Gabriel Socol, Eric Lambers, Roxana Trusca, Steven Fairchild, Tyson Back, Greggory Gruen, Doina Craciun; Characteristics of LaB6 thin films grown by pulsed laser deposition. J. Vac. Sci. Technol. A 1 September 2016; 34 (5): 051509. https://doi.org/10.1116/1.4960647
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