Substantial reduction of the dielectric losses of Ba0.6Sr0.4TiO3 thin films using a SiO2 barrier layer

The efficient use of ferroelectric thin films in radio-frequency agile devices faces several limitations. One of them is imposed by the dielectric losses which are usually above 1%, i.e. above the threshold as set by the electronic industry. Following the same route as for bulk ceramics, we have processed composite stacks made of BST/SiO2 multilayers using radio-frequency magnetron sputtering. Doing so, we were able to repeatedly achieve dielectric losses well below 0.5% while keeping a high dielectric susceptibility and a suitable tunability. All of these improvements have been observed at low frequencies (f < 10 MHz) and the transfer to the targeted frequency range (f > 1 GHz) is currently in progress.