Dielectric properties of soft chemical method derived CaCu3Ti4O12 thin films onto Pt/TiO2/Si(100) substrates

Abstract

a b s t r a c tCalcium copper titanate, CaCu 3 Ti 4 O 12 (CCTO), thin film has been deposited by the soft chemical method on Pt/Ti/SiO 2 /Si (1 0 0) substrates at 700 • C for 2 h. The peaks were indexed as cubic phase belonging to the Im−3 space group. The film exhibited a duplex microstructure consisting of large grains of 130 nm in length and regions of fine grains (less than 80 nm). The CCTO film capacitor showed a dielectric loss of 0.031 and a dielectric permittivity of 1020 at 1 MHz. The J-V behavior is completely symmetrical, regardless of whether the conduction is limited by interfacial barriers or by bulk-like mechanisms. Based on impedance analyses, the equivalent circuit of CCTO film consisting of a resistor connected in series with two resistor-capacitor (RC) elements.

Effect of RF sputtering power on morphological and electrical properties of calcium copper titanate thin films

“…The absorption band appeared at 612 cm −1 corresponds to the silicon substrate. The band centered at 740 cm −1 indicates the crystallization of CCTO film [30]. There is an appearance of an absorption band at 430 cm −1 for higher RF Powers, which corresponds to ν-Ti-O-Ti [29,31].…”

“…Initially, the current was found to be increased linearly with low electric field strengths suggesting an ohmic conduction. This ohmic behavior occurs in insulating film as long as the film is quasi neutral, that is, as long as the bulk generated current in the film exceeds the current due to injected free carriers from the electrode [30]. This current is due to the hopping conduction mechanism in a low electric field because of the thermal excitations of trapped electrons.…”

Low temperature sintered giant dielectric permittivity CaCu3Ti4O12 sol-gel synthesized nanoparticle capacitors

“…9 According to Kr€ oger-Vink defect notation, during sintering process, oxygen vacancies were formed due to loss of the oxygen. 35,36 Upon cooling, insulating grain boundaries re-oxidize faster (grain boundary diffusion) than that of semiconducting grain V. S. Puli et al J. Adv. Dielect.…”

“…This linear increase in ac relates to the electrical conduction by electron exchange between (Cu þ2 $ Cu þ1 Þ the Cu ions with different valence (Cu þ2 and Cu þ1 ) states. [35][36][37] The electrons released in the above reaction were captured by the Cu þ2 to form Cu þ1 (Cuþ). This leads to hopping of electrons among the two different valence states, which increases the conductivity of the grains.…”

“…This leads to hopping of electrons among the two different valence states, which increases the conductivity of the grains. [35][36][37] However, in case of stoichiometric CCTO, the conduction mechanism is attributed to the hopping of the charge carriers between the Cu 2þ and Cu 3þ . 29 …”