Active layers of high-performance lead zirconate titanate at temperatures compatible with silicon nano- and microelecronic devices

Applications of ferroelectric materials in modern microelectronics will be greatly encouraged if the thermal incompatibility between inorganic ferroelectrics and semiconductor devices is overcome. Here, solution-processable layers of the most commercial ferroelectric compound ─ morphotrophic phase boundary lead zirconate titanate, namely Pb(Zr0.52Ti0.48)O3 (PZT) ─ are grown on silicon substrates at temperatures well below the standard CMOS process of semiconductor technology. The method, potentially transferable to a broader range of Zr:Ti ratios, is based on the addition of crystalline nanoseeds to photosensitive solutions of PZT resulting in perovskite crystallization from only 350 °C after the enhanced decomposition of metal precursors in the films by UV irradiation. A remanent polarization of 10.0 μC cm−2 is obtained for these films that is in the order of the switching charge densities demanded for FeRAM devices. Also, a dielectric constant of ~90 is measured at zero voltage which exceeds that of current single-oxide candidates for capacitance applications. The multifunctionality of the films is additionally demonstrated by their pyroelectric and piezoelectric performance. The potential integration of PZT layers at such low fabrication temperatures may redefine the concept design of classical microelectronic devices, besides allowing inorganic ferroelectrics to enter the scene of the emerging large-area, flexible electronics

Antiferroelectric lead zirconate thin films by excimer laser ablation

Utilization of antiferroelectric thin films was proposed for high charge storage capacitors and transducer applications. The volume changes that are associated with the AFE [right double arrow] FE and FE [right double arrow] AFE phases are high enough to use them in MEMs device technology. Lead zirconate was the first identified antiferroelectric compound with a reported dielectric phase transition temperature of [similar to] 230°C. In this article, deposition of lead zirconate thin films by a pulsed excimer laser ablation technique is reported. The antiferroelectric nature of the lead zirconate thin films were confirmed by the presence of double hysteresis loop in polarization vs. applied electric field response as well as double butterfly behavior in capacitance vs. voltage characteristics. The variations in the polarization hysteresis with temperature were elucidated in detail. The switching times between the field induced FE and AFE phases (backward switching) were studied at various applied electric field

Antiferroelectric lead zirconate thin films by pulsed laser ablation

Lead Zirconate (PbZrO3) thin films were deposited by pulsed laser ablation method. Pseudocubic (110) oriented in-situ films were grown at low pressure. The field enforced anti-ferroelectric (AFE) to ferroelectric (FE) phase transformation behaviour was investigated by means of a modified Sawyer Tower circuit as well as capacitance versus applied voltage measurements. The maximum polarisation obtained was 36 mu C cm(-2) and the critical field to induce ferroelectric state and to reverse the antiferroelectric slates were 65 and 90 kV cm(-1) respectively. The dielectric properties were investigated as a function of frequency and temperature. The dielectric constant of the AFE lead zirconate thin him was 190 at 100 kHz which is more than the bulk ceramic value (120) with a dissipation factor of less than 0.07. The polarisation switching kinetics of the antiferroelectric PbZrO3 thin films showed that the switching time to be around 275 ns between antipolar state to polar states. (C) 1999 Elsevier Science S.A. All rights reserved

Field-induced dielectric properties of laser ablated antiferroelectric (Pb_0_._9_9Nb_0_._0_2)(Zr_0_._5_7Sn_0_._3_8Ti_0_._0_5)_0_._9_8O_3 thin films

Niobium-modified lead zirconate stannate titanate antiferroelectric thin films with the chemical composition of (Pb_0_._9_9Nb_0_._0_2)(Zr_0_._5_7Sn_0_._3_8Ti_0_._0_5)_0_._9_8O_3 were deposited by pulsed excimer laser ablation technique on Pt-coated Si substrates. Field-induced phase transition from antiferroelectric to ferroelectric properties was studied at different fields as a function of temperature. The field forced ferroelectric phase transition was elucidated by the presence of double-polarization hysteresis and double-butterfly characteristics from polarization versus applied electric field and capacitance and voltage measurements, respectively. The measured forward and reverse switching fields were 25 kV/cm and 77 kV/cm, respectively. The measured dielectric constant and dissipation factor were 540 and 0.001 at 100 kHz, respectively, at room temperature

Dielectric relaxation in antiferroelectric multigrain PbZrO3PbZrO_3 thin films

Antiferroelectric materials are found to be good alternative material compositions for high charge storage devices and transducer applications. Lead zirconate (PZ) is a room temperature antiferroelectric material. Thin films of PZ with various thicknesses were deposited by excimer laser ablation technique on Pt coated Si-substrates at a substrate temperature of 300°C and,subsequently, post annealed at 650°C. The antiferroelectric nature of PZ thin films was studied over a temperature range 30–250°C. Effect of thickness on the net dielectric constant was studied in detail and the calculated interfacial dielectric layer thickness is 0.1 nm approximately, with a bulk dielectric constant of 222 at 100 kHz. Impedance and electric modulus formalisms were employed in order to gain an insight of the microstructural details of multigrain thin films. A comprehensive study on relaxation mechanism revealed that the Maxwell–Wagner type polarization is the basic relaxation phenomenon in the multigrain PZ thin films, due to the presence of multiple grain and grain boundaries across the film thickness. The activation energies from the interior grain relaxation and ac conductivity studies were 0.631 and 0.563 eV, respectively. These activation energies were attributed to the excitation of the charge carriers from a set of shallow traps and:or oxygen vacancies present at an average depth of 0.5–0.6 eV from the bottom of the conduction band

Antiferroelectric thin films for MEMS applications

Antiferroelectric compositions have many potential applications in energy conversion and microelectromechanical systems. Electric field induced phase transitions between ferroelectric and antiferroelectric phases were studied in antiferroelectric lead zirconate and modified lead zirconate titanate stannate family thin films for various smart system applications. Thin films of various antiferroelectric thin film compositions such as $PbZrO_3$, Nb- and La-modified lead zirconate titanate stannate were processed by the pulsed excimer laser ablation technique. Dielectric, hysteresis, pyroelectric and switching properties were studied in detail for a new generation of functional materials. A comparative study of functional properties is presented with these antiferroelectric compositions in comparison with the conventional ferroelectric composition

Growth and study of antiferroelectric lead zirconate thin films by pulsed laser ablation

Antiferroelectric lead zirconate (PZ) thin films were deposited by pulsed laser ablation on platinum-coated silicon substrates. Films showed a polycrystalline pervoskite structure upon annealing at 650 degrees C for 5-10 min. Dielectric properties were investigated as a function of temperature and frequency. The dielectric constant of PZ films was 220 at 100 kHz with a dissipation factor of 0.03. The electric field induced transformation from the antiferroelectric phase to the ferroelectric phase was observed through the polarization change, using a Sawyer-Tower circuit. The maximum polarization value obtained was 40 mu C/cm(2). The average fields to excite the ferroelectric state, and to reverse to the antiferroelectric state were 71 and 140 kV/cm, respectively. The field induced switching was also observed through double maxima in capacitance-voltage characteristics. Leakage current was studied in terms of current versus time and current versus voltage measurements. A leakage current density of 5x10(-7) A/cm(2) at 3 V, for a film of 0.7 mu m thickness, was noted at room temperature. The trap mechanism was investigated in detail in lead zirconate thin films based upon a space charge limited conduction mechanism. The films showed a backward switching time of less than 90 ns at room temperature

Field-induced dielectric properties of laser ablated antiferroelectric (Pb0.99Nb0.02)(Zr0.57Sn0.38Ti0.05)0.98O3 thin films

Niobium-modified lead zirconate stannate titanate antiferroelectric thin films with the chemical composition of (Pb0.99Nb0.02)(Zr0.57Sn0.38Ti0.05)0.98O3 were deposited by pulsed excimer laser ablation technique on Pt-coated Si substrates. Field-induced phase transition from antiferroelectric to ferroelectric properties was studied at different fields as a function of temperature. The field forced ferroelectric phase transition was elucidated by the presence of double-polarization hysteresis and double-butterfly characteristics from polarization versus applied electric field and capacitance and voltage measurements, respectively. The measured forward and reverse switching fields were 25 kV/cm and 77 kV/cm, respectively. The measured dielectric constant and dissipation factor were 540 and 0.001 at 100 kHz, respectively, at room temperature

Study of AC electrical properties in multigrain antiferroelectric lead zirconate thin films

Antiferroelectric lead zirconate (PZ) thin films were deposited by excimer laser ablation technique on Pt-coated Si substrates. Antiferroelectric thin film compositions are potential candidates for high charge storage and microelectromechanical systems. The antiferroelectric nature in PZ thin films was confirmed by means of double hysteresis behaviour in polarisation vs. applied electric field and double butterfly response in capacitance vs. applied voltage measurements. The maximum spontaneous polarisation observed was $37 \mu C/cm^2$ with zero remnant polarisation at an applied electric field of 225 kV/cm. PZ thin films showed a polycrystalline multigrain structure and detail comprehensive study of dielectric relaxation and ac electrical properties were carried out

Conduction mechanism in antiferrolectric PbZrO3PbZrO_3 thin films. Analysis of charge carrier trapping phenomenon

Antiferroelectric compositions, such as $PbZrO_3$, are attractive candidates in charge storage devices and actuator/transducer applications in MEMs technology. Thin films of $PbZrO_3$ were deposited on Pt coated Si substrates by a pulsed excimer ablation process. The process of field induced ferroelectric phase switching involves the domain wall reorientation in the polycrystalline thin films. The presence of grain boundaries and various defects in the polycrystalline thin films acts as the pinning sources for the various domain walls. These defects capture the charge carriers in the presence of external applied field and hinders further switching of the dipoles in the domains, thereby increasing the response times and threshold voltages for the devices operations. Understanding of the trapping phenomenon in these films is very essential. Using Lampert's theory of space charge limited conduction both shallow and deep trap energies were estimated approximately from charge transport analysi