Characteristics of single crystal “thin film” capacitor structures made using a focused ion beam microscope

Abstract

The focused ion beam microscope was used to isolate thin parallel-sided lamellae from single crystals of BaTiO3 and SrTiO3. Damage and ion-implantation on the faces of the lamellae were observed, but could be removed by thermal annealing. A series of lamellae ranging in thickness from ∼660 to ∼300 nm were made from a SrTiO3 single crystal, and after thermal annealing, gold electrodes were deposited on either side to form parallel-plate capacitor structures. The room temperature functional properties of these single crystal “thin film” capacitors were investigated. Although space-charge artifacts dominated the low frequency response, above 10 kHz, examination of the change in capacitance as a function of lamellar thickness allowed the room temperature relative dielectric constant to be meaningfully extracted. This was found to be ∼300, as is the case in bulk. For these single crystal lamellae there was therefore no evidence of a collapse in dielectric constant associated with thin film dimensions.