Low concentration (x < 0.01) Gd doping of CeO2 thin films for n-type layers deposited by spin coating

Abstract

CeO2 thin films with (x) Gd concentration 0.0006 < x < 0.4 were synthesized by spin coating. At low Gd concentrations, x < 0.01, x-ray diffraction showed negligible variations in the lattice parameter and the material behaved as Gd doped CeO2 with an electron concentration, measured by Hall effect, that varied from 6.5×1014 to 9.4×1016 cm−3. On the other hand, for x > 0.01, the lattice parameter increased in agreement to the addition of Gd atoms and the generation of oxygen vacancies. Raman spectroscopy showed that the main phonon shift had two contributions of opposite sign related to the changes in atomic bonding length and the presence of oxygen vacancies. Two p-n junctions were formed with a x = 0.0025 CeO2:Gd layer and two different thin films as the p-type material, Sb2S3 and Si. Both heterostructures showed electronic diode behavior, confirming the doping of CeO2 with Gd.