Academic literature on the topic 'La doped PZT'

Integrated metal-insulator-metal (MIM) capacitors using sol-gel PZT doped with lanthanum (La, PLZT), manganese (Mn, PMZT) and niobium (Nb, PNZT) were successfully processed and characterized for tunable applications. Dielectric properties of doped-PZT were investigated and compared to those of pure PZT. Wafer-level measurements were conducted with a particular attention on tunability evaluation under DC bias voltage. Tunability, leakage current density and breakdown voltage of pure PZT thin films were 77.6% (i.e. 4.5:1) at 10kHz/10V, 4.8.10−5 A/cm2 at 870kV and 37.5V (i.e. 1.63 MV/cm) respectively. The breakdown voltage increased by 25% with La doping and by 50% with Nb and Mn. The lowest leakage current were achieved by PNZT (7.0.10−7 A/cm2 at 870kV) while PMZT films exhibited an outstanding tunability reaching 88.8% (i.e. 8.9:1) at 100 kHz and 20V. Enhanced performances of the developed doped-PZT were compared to the state of the art. Results indicate that electrical properties of sol-gel doped-PZT achieved those of conventionally deposited materials. It is noteworthy that obtained PMZT tunability is among the highest ones reported in the literature for PZT-derived thin films but also for other piezoelectric materials.

Modern RF systems have triggered an important and urgent demand for inexpensive voltage controlled capacitors used for a wide range of applications such as tunable antennas or low-noise voltage-controlled oscillators (VCO). Ferroelectric materials have received considerable interest for electrically tunable dielectrics due to their high dielectric constant and large dielectric nonlinearity under dc bias field. Lead zirconate titanate (PZT) ceramics which have been under intense investigation for various industrial domains including micro-electro-mechanical systems (MEMS), non-volatile memories, and high-k capacitors, are especially well-known candidate materials due to their unequalled ferroelectric properties and stability in device operating ranges. However, reported voltage tunability of PZT films is relatively low (~35%@4GHz) and remains insufficient for microwave tunable devices. Therefore, much attention has been focused on the PZT modification by adding a small amount of dopants. Shao et al., studied strontium-doped PZT (PSZT) thin films and achieved a tunability of 48% @1MHz. More recently, Hu et al. reported a tunability of 65%@10kHz for lanthanum-modified PZT (PLZT) films. In the presented study, effect of manganese (Mn) doping on electrical properties of PZT (PMZT) thin films has been investigated. Metal/insulator/metal (MIM) capacitors using PZT-based thin films and ruthenium (Ru) top electrodes were processed on platinized (Pt) silicon wafers by a sol gel method. Dielectric properties of PMZT thin films were studied by varying the dopant amount and compared to those of pure PZT layers. At this end, on-wafer electrical measurements were conducted with a particular attention on leakage current characterization and RF measurements under DC bias voltage. We have shown that leakage current density decreased from 6.5 μA/cm2 to 1 μA/cm2 at 850kV/cm by doping PZT with Mn. Observed conduction mechanisms will be discussed in detail in the full-length paper. Moreover, developed PZT-based thin films exhibit high dielectric strengths achieving 2.1MV/cm and outstanding tunability as high as 85% (~7:1) @1GHz at bias voltage of 20V. Thus, PMZT tunability is among the highest ones reported in the literature for PZT-derived thin films but also for other piezoelectric materials. Indeed, in comparison, the tunability of BST-based materials, typically studied for voltage tunable applications, does not exceed 5:1. These remarkable results indicate that Mn-doped PZT thin films are promising candidates for RF tunable capacitors.

The physical layering of sol-gel-derived lead zirconate titanate (PZT) 52/48 and lanthanum-doped PZT (PLZT) 2/52/48 on platinized silicon substrates was investigated to determine if the ferroelectric properties and fatigue resistance could be influenced by different layering sequences. Monolithic thin films of PZT and PLZT were characterized to determine their ferroelectric properties. Sandwich structures of Pt/PZT/PLZT/PLZT/PZT/Au and Pt/PLZT/PZT/PZT/PLZT/Au and alternating structures of Pt/PZT/PLZT/PZT/PLZT/Au and Pt/PLZT/PZT/PLZT/PZT/Au were then fabricated and characterized. X-ray photoelectron spectroscopy depth profiles revealed that the layering sequence remained intact up to 700 °C for 45 min. It was found that the end layers in the multilayered films had a significant influence on the resulting hysteresis behavior and fatigue resistance. A direct correlation of ferroelectric properties and fatigue resistance can be made between the data obtained from the sandwiched structures and their end-layer monolithic thin film counterparts. Alternating structures also showed an improvement in the fatigue resistance while the polarization values remained between those for PZT and PLZT thin films.

Lead Zirconate Titanate (PZT) undoped and doped was prepared by using solid state reaction method. In this paper, PZT is doped with another elements with is La3+ and Sr2+ in order to enhance the properties of PZT. The samples were prepared via high planetary mill which is can skip the calcination process that can cause of PbO loss during firing. With the help of x-ray diffraction (XRD) and scanning electron microscopy (SEM), the formation of perovskite structure into newly modified ceramics was investigated and the grain growth of pure PZT and doped PZT were also investigated which is can enhance their properties which may be suitable for possible device applications.

This study examined the effect of crystalline orientation and dopants such as Nb and Zn on the piezoelectric coefficient of sol-gel driven Pb1(Zr0.52Ti0.48)O3(PZT) and doped PZT thin films. Crack-free 1-μm-thick PZT and doped PZT thin films prepared by using 2-Methoxyethanol-based sol-gel method were fabricated on Pt/Ti/SiO2/Si substrates. The highly (111) oriented PZT thin films of pure perovskite structure could be obtained by controlling various parameters such as a PbTiO3 seed layer and a concentration of sol-gel solution. The Nb-Zn doped PZT thin films exhibited high piezoelectric coefficient which was about 50 % higher than that of undoped PZT thin film. The highest measured piezoelectric coefficient was 240 pC/N, which could be applicable to piezoelectrically operated MEMS actuator, sensor, or energy harvester devices.

The effects of the complex donor and acceptor additives on the microstructure, piezoelectric and dielectric properties of PZT (Zr/Ti=53/47) ceramics were studied. A complex doping with the soft (La+3 and Nb+5) and hard (Fe+3 and/or Mn(+2,+3 or +4)) ions has been adopted. The complex doping of two or more elements is expected to combine the properties of donor and/or acceptor doped PZT, which could exhibit better stability or improved piezoelectric properties than those of the single element doped PZT. The complex doping caused various compensation effects for the piezoelectric properties of PZT ceramics; Mn addition to the La/Nb and Fe doped PZT composition led to the improved piezoelectric properties, i.e., enhanced Qm with remaining considerably high kP.