Premium
Optical and electrical properties of terbium films as a function of hydrogen concentration
Author(s) -
Azofeifa Daniel,
Clark Neville,
Vargas William
Publication year - 2005
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200540061
Subject(s) - van der pauw method , terbium , hydrogen , analytical chemistry (journal) , electrical resistivity and conductivity , dielectric , materials science , refractive index , absorption (acoustics) , work function , quartz crystal microbalance , absorption spectroscopy , spectral line , semiconductor , chemistry , metal , optics , optoelectronics , adsorption , luminescence , composite material , hall effect , astronomy , physics , organic chemistry , chromatography , electrical engineering , metallurgy , engineering
The absorption of hydrogen in the rare earth metals produces interesting changes in their optical and electrical properties. In this work we study these properties on Tb films, 50 nm thick, as a function of hydrogen concentration. The Tb films are covered with a 15 nm thick Pd overcoat which allows hydrogenation while protecting the highly reactive Tb film from contamination. Electrical resistivity is measured using the van der Pauw method, the transmission spectra are measured in the visible region and the concentration using a quartz crystal microbalance. The maximum concentration reached was 2.95 H/Tb at a hydrogen pressure of 450 Torr. From the measured transmission spectra, using a Spectral Projected Gradient Method, we obtain the Tb film's complex refractive index. From this we calculate the real and imaginary parts of the dielectric function, ε 1 and ε 2 , and follow their evolution as a function of hydrogen concentration. ε 1 changes from negative values, characteristic of metals, to positive values characteristic of semiconductors and dielectrics. ε 2 decreases indicating a significant decrease in light absorption. These results are similar to those observed on Dy, Gd, La and Y films. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)