In-plane conductivity of thin films and heterostuctures based on LaF3-SrF2
The in-plane conductivity of solid solution la1-xsrxf3-x (x = 0 ÷ 0.24) films with thicknesses from 40 to 260 nm grown on glass-ceramics based on sio2, al2o3, caf2 (111) and mgo (100) substrates, and laf3-srf2 heterostructures grown on mgo (100) substrates were studied by impedance spectroscopy at temperature range from room temperature to 300 °c and at frequencies from 10-1 to 106 hz.
It was found that there was a maximum of ionic conductivity for la1-xsrxf3-x (x = 0 ÷ 0.24) solid solution films at x ≈ 0.05. The conductivity of la0.95sr0.05f2.95 films is by 2 - 4 orders of magnitude higher than that of pure lanthanum fluoride films on the substrates of magnesium oxide, sapphire and glass-ceramics. It was also shown that there was a maximum of in-plane conductivity of laf3-srf2 heterostructures for the thickness of each layer ~ 20 nm. The activation energy was evaluated from the temperature dependencies of the dc-conductivity of the films according to Arrhenius - Frenkel law. It was 400 - 800 mev for all measured samples.