Thickness-dependence of growth rate, dielectric response, and capacitance properties in Ba0.67Sr0.33TiO3/LaNiO3 hetero-structure thin films for film capacitor applications

This work reports the structure, growth rate, dielectric response, and capacitance properties of (100)-oriented Ba0.67Sr0.33TiO3 (BST)/LaNiO3 (LNO) hetero-structure thin films with varied BST layer thicknesses from 34 nm to 342 nm. The BST/LNO hetero-structure thin films were prepared by radiofrequency magnetron sputtering technique on Pt/SiO2/Si substrates. The XRD results showed that the compressive stress is relaxed at around 73 nm of BST layer, and above 119 nm of the BST layer thickness, the tensile stress has a significant effect on the crystal structure of the BST/LNO hetero-structure film. The growth rate of the BST films was thickness-dependent which was strongly related to the minimization of the strain energy. The dielectric constant of BST layer with the compressive stress increase from 177 to 2640 with the increase of BST layer thickness. The BST layer with the tensile stress showed a comparably stable dielectric constant of 2400. In addition, the capacitance properties and the electrical breakdown strength of BST/LNO hetero-structure thin films are also thickness-dependent, respectively. The electrical breakdown strength reached a maximum value of 1237 kV/cm in the BST/LNO hetero-structure thin film with ~73 nm BST layer.