Leakage current of sol-gel derived Pb(Zr, Ti)O3 thin films having Pt electrodes

Abstract

The electrical conduction behaviors of sol-gel derived Pb(Zr, Ti)O3 (PZT) thin films on Pt electrodes were analyzed based on a fully depleted film, thermionic field emission, and space charge limited conduction model in the low and high electric field regions, respectively. For films having thicknesses ranging from 150 to 250 nm, no thickness-dependent variation in the dielectric constant was observed due to the relatively large thicknesses. The rather small film-thickness-dependent leakage current characteristics in the low-field region elucidates that the positive space charge density in the film is about 1018 cm−3, which is a smaller value than that of the sputter deposited (Ba, Sr)TiO3 thin films by an order of magnitude. The calculated interfacial potential barrier height and effective mass of electrons were 0.93 eV and 0.09m0, respectively. The slope larger than 2 from the log J vs log V plot in the high-field region implies that the energy level of electron traps are continuously distributed in the energy band gap.

General equivalent circuit derived from capacitance and impedance measurements performed on epitaxial ferroelectric thin films

“…The fact that the capacitance still has a voltage dependence after polarization reversal support the presence of Schottky type contacts at the electrode interfaces, as already suggested in the literature. [45][46][47][48][49][50][51] One can see that the capacitance values are different for different metals used as top contacts. This fact strongly suggests that the electrode interfaces play an important role in the electric/ dielectric properties of epitaxial ferroelectric thin films.…”

Effect of rf power on the dielectric properties of bismuth magnesium niobium titanium thin films deposited by RF magnetron sputtering

“…5, under the same bias electric field, the leakage current increases with the rising of rf power. This is thought to be strongly influenced by surface roughness of BMNT thin films [27][28][29]. As mentioned above in Fig.…”

Effect of post-annealing on leakage currents of (Ba,Sr)TiO3 thin film prepared by pulsed laser deposition

“…This small barrier height results in the large injection of electrons under an applied bias. When the injecting electron density per given time is larger than the density of electrons passing across from the cathode to anode, SCLC occurs [6]. For the film after the second post-annealing the Schottky barrier height improves greatly, which significantly decreases carrier injection from the cathodic interface compared to the case of the as-deposited film.…”

“…where e r is the relative dielectric constant, e 0 is the permittivity of free space, l e is the electron mobility, V is the applied voltage, d is the film thickness and h is the ratio of free to trapped charges [6,7]. For the film after the second post-annealing, the plot of log J versus V 1/2 is shown in Fig.…”

“…Both of the plots of log J versus log V show good linearity especially at high voltage region and both of the slopes of the plots are close to 2.0. These suggest that the leakage conduction mechanism is space charge limited conduction (SCLC) mechanism [6]. When a single discrete trap level exists in the band gap, current density J dominated by SCLC is typically given as:…”