Tunable characteristics of (Ba0.5Sr0.5) TiO3 (BST) capacitors using (Ba0.5Sr0.5) RuO3 (BSR) interfacial layers onto Pt/Ti/SiO2/Si substrates

Abstract

The conducting oxide electrodes (Ba, Sr) RuO3 (BSR) similar in structure and chemical composition to (Ba, Sr) TiO3 (BST) were deposited by metalorganic chemical vapor deposition (MOCVD) onto Pt/Ti/SiO2/Si substrates to improve the structural and dielectric properties of BST films. The BSR interfacial layers between the BST and Pt bottom electrode influenced the preferred orientation, surface morphologies, and dielectric properties of BST films. The structural and dielectric properties of BST films depended on the thickness of the BSR layers. BST films with (100) texturing up to 150 A thickness of BSR showed a smoother and smaller grain size than those without interfacial layers, and a tunability and dielectric constant of about 70% and 1300 at an interfacial layer of 150 A, respectively. On the other hand, BST films with above 300 A thickness in BSR layers showed a (110) texturing similar to those without BSR layers and a slight decrease of tunability and dielectric constant compared with those of (100) texturing BST films. The increase of the dielectric loss of BST films with BSR layers was attributed to the carbon contamination diffused from MOCVD-BSR layers.