Reduction of microwave dielectric losses in KTa1−xNbxO3 thin films by MgO-doping
Résumé
KTa1 − xNbxO3 (KTN) thinfilms were grown by pulsed laser deposition on sapphire and MgO substrates. Their structural and high frequency dielectric characteristics evidenced the strong influence of the substrate and suggested possible KTN/MgO interdiffusion that could be responsible for the lower dielectriclosses obtained on this substrate. Both undoped and 6% MgO-doped KTN thinfilms were then grown on sapphire. Dielectric measurements performed at 12.5 GHz by a resonant cavity perturbation method evidenced reduction of losses by MgO-doping. Loss tangent (tan δ) was reduced by a factor of 3 in comparison with undoped films grown on sapphire.