Feasibility Of (Pb1-xCax)TiO3 Thin Films With x ~0.5 For Electronic Applications

Abstract. Calcium modified lead titanate thin films, Pb 1 -x Ca x TiO 3 , with x ~ 0.5 have been deposited onto the crystalline (Pt/TiO 2 /SiO 2 /(100)Si, and Pt/(100)SrTiO 3 substrates by spinning-on and crystallisation of several layers of sol-gel precursor solutions. The layers are crystallized by a rapid thermal processing (RTP). Dielectric measurement with temperature and frequency show a wide broadening of the maximum of the permittivity close to room temperature, with high values of dielectric constant (K′ ~ 350), moderate dielectric losses (tgδ ~ 0.05) and positive shift of temperature of the maximum, T m , for increasing frequencies that follows the empirical Vogel-Fulcher law, which could be interpreted as a relaxor behaviour. The high density of capacitance/μ 2 and low leakage currents lead to high retention of its charge that promises its use in DRAM. Measurements of capacitance with bias voltage (C-V) at different temperatures and frequencies show an interesting non-linear behaviour (varactor effect) with tunabilities about 70% and figure of merit of FOM > 30%. Therefore, these films can be considered as an alternative to traditional materials for voltage-tuneable devices for high frequencies.