Dielectric Properties of Atomic Layer Deposited Thin-Film Barium Strontium Titanate

Thin-film capacitor heterostructures were formed by atomic layer deposition of 54 nm thick polycrystalline barium strontium titanate film on silicon substrates using Pt top and bottom electrodes. The dielectric response of capacitors was experimentally studied as a function of frequency, temperature, and applied field, and analyzed considering presence of an interface capacitance. In thin-film BST, a paraelectric state with low Curie temperature, small Curie constant, and small intrinsic permittivity is detected. The results are discussed in terms of depolarizing field, effect of low-permittivity inclusions, and grains. The commutation quality factor of capacitors is found to be satisfactory for tunable devices.