2014 Volume 122 Issue 1426 Pages 477-482
We proposed a thin-film capacitor with a stable temperature coefficient of capacitance (TCC) based on bismuth layer-structured dielectrics, CaBi4Ti4O15. Two types of doping were conducted to lower the dielectric loss in a higher temperature range above 300°C, i.e., Mn ion to compensate for lattice defects in crystalline grains and Bi12SiO20 to form a grain boundary phase were attempted in order to improve the insulating property of the oriented CaBi4Ti4O15 films. (00l) one-axis oriented Mn-doped or Bi12SiO20-doped CaBi4Ti4O15 films (with Mn or Bi12SiO20 content up to 3.0 or 1.75%) were fabricated successfully on (111)Pt/TiO2/(100)Si substrates buffered by (001)Ca2Nb3O10 nanosheets. These films exhibited a relatively lower loss factor in the temperature range from R.T. up to 400°C. In particular, the behavior of TCC on the Bi12SiO20-doped CaBi4Ti4O15 film was significantly stable, with a change in capacitance, ΔC/CR.T., within ±10% even at 400°C.