Abstract
The influence of Mg incorporation into A- and B-sites of the perovskite lattice of SrTiO₃ ceramics on the structural, microstructural and low-frequency dielectric properties is studied in this work. Compounds in the systems Sr_1-xMg_xTiO₃ and SrTi_1-yMg_yO_3-delta were synthesised by a conventional solid-state method. The solid solubility of Mg is restricted to x1-xMg_xTiO₃) and to y1-yMg_yO_3-delta). The lattice parameter is found to increase with Mg content for the SrTi_1-yMg_yO_3-delta system, while it is almost invariant in the Sr1-xMgxTiO3 one. The dependence on the lattice-site occupancy is also verified for the grain growth of ceramics. For SrTi_1-yMg_yO_3-delta the average grain size markedly decreases with increasing Mg content. For Sr_1-xMg_xTiO₃ the inverse dependence is observed. Contrary to expectations, Mg does not induce ferroelectricity or relaxor-like behaviour in strontium titanate, located in either A- or B-sites of the SrTiO₃ lattice. Moreover, fitting the dielectric behaviour to Barrett’s law demonstrates that B-site doping drives the system away from the ferroelectric instability. In Mg-doped strontium titanate ceramics the dielectric permittivity and dielectric losses decrease. The results are discussed based on the correlation between cation-site occupancy, charge and chemical stoichiometry in both systems.
DOI: 10.1007/s00339-003-2341-z

Abstract
This work presents a study on the effect of an interfacial silicon oxide layer placed between Au and a-Si:H MIS (metal–insulator–semiconductor) photodiodes in their performances, by stopping the Au diffusion towards the a-Si:H. The results show that the Au diffuses very easily to the oxide free a-Si:H surface, even at room temperature, degrading the photodiode performance. On the other hand, the MIS photodiodes with the interfacial oxide show an improvement of their characteristics after annealing, function of its thickness, and degree of film’s compactness. This effect is associated with the presence of oxide of thicknesses ⩾5 Å at the Au/a-Si:H interface that prevents the Au diffusion and improves the photodiode characteristics, which does not happen when the interfacial oxide is absent.
DOI: 10.1016/j.jnoncrysol.2004.03.097

Abstract
The study of the influence of different tin concentrations in the In–Sn alloy on the properties of indium tin oxide (ITO) thin films deposited by radio frequency (rf) plasma enhanced reactive thermal evaporation (rf-PERTE) onto flexible polymer and window glass substrates at room temperature is presented. The polymer substrate used is polyethylene terephthalate (PET). The tin concentration in the source alloy varied in the range 5–20 wt.%. The average thickness of the ITO films is of about 90 nm. Results show that ITO thin films deposited on PET from the evaporation of a 85%In:15%Sn alloy exhibit the following characteristics: an average visible transmittance of 80% and an electrical resistivity of 1.6×10⁻³ Ω cm. On glass the value of the average visible transmittance increases (85%) and the resistivity decreases to 7.6×10⁻⁴ Ω cm. The electrical properties of ITO films on PET are largely affected by the low carrier mobility.
DOI: 10.1016/j.mseb.2003.10.089

Abstract
Thin film transistors (TFTs) made of silicon nitride and silicon carbide as dielectric were submitted to N₂, H₂ and O₂ plasma treatment of the insulator/semiconductor interface. Silicon nitride is widely used as gate dielectric with very good bulk properties but with network matching problems at the interface with amorphous silicon. Carbon-rich silicon carbide can be an alternative as dielectric material, presenting improved SiC/a-Si interface properties, but having lower bulk performance. The purpose of such interface plasma processing is to passivate, oxidize or insert nitrogen atoms into the last deposited monolayers and observe the effect of ion bombardment in the interface. Results show an increase of the field effect mobility from 0.38 to 0.51 cm²V⁻¹s⁻¹ in the passivated (hydrogenated) a-SiN_X TFTs. An improvement is also observed in a-SiCX TFTs treated with H₂ plasma, but less evident. Some correlation has been found between H bonding in insulating films, extracted by FTIR measurements and the different response found for a-SiC_X and a-SiN_X based TFTs to H₂ plasma treatment.
DOI: 10.1016/j.mseb.2003.10.079

Abstract
Lattice dynamics and dielectric relaxation phenomena of (Sr_1-1.5xBi_x)TiO₃ ceramics with x=0.0067–0.133 were studied in the temperature range of 10–400 K. The polar TO1 soft mode in the IR spectra is strongly stiffened by Bi doping and its softening on cooling is gradually stopped. Increasing degree of local polar distortion induced by doping was detected by progressive activation of TO2 and TO4 polar modes in the Raman spectra. Wide range (10²–1.8×10⁹; 10¹¹–2×10¹³Hz) dielectric spectra were determined and carefully fitted with an appropriate model of relaxation time distribution. At least four relaxation regions were revealed and the dominant thermally activated region was assigned to nanocluster polarization dynamics. The enhanced absorption in the submillimeter range was assigned to anharmonic quasi-Debye losses.
DOI: 10.1103/PhysRevB.69.144104

Abstract
The aim of this paper is to study the role of different metals (aluminium, molybdenum, nickel and titanium) in inducing crystallization in films produced by LPCVD at high and low temperature processes and to compare the structural, morphological, optical and electrical properties of the various films produced. This work envisages the use of the most suitable conditions that lead to the production of films for optoelectronic applications such as solar cells.
DOI: 10.1016/j.tsf.2003.10.124

Abstract
Transparent and highly conducting gallium-doped zinc oxide films were successfully deposited by rf sputtering at room temperature. The lowest resistivity achieved was 2.6×10⁻⁴ Ω cm for a thickness of 1100 nm (sheet resistance ≈1.6 Ω/sq), with a Hall mobility of 18 cm²/Vs and a carrier concentration of 1.3×10²¹ cm⁻³. The films are polycrystalline with a hexagonal structure and a strongly preferred orientation along the c-axis. A linear dependence between the mobility and the crystallite size was obtained. The films present a transmittance in the visible spectra between 80 and 90% and a refractive index of approximately 2, which is very close to the value reported for bulk material.
DOI: 10.1016/j.tsf.2003.10.139

Abstract
Gallium-doped zinc oxide (GZO) thin films have been deposited onto polyethylene naphthalate (PEN) substrates by r.f. magnetron sputtering at room temperature. The influence of the film thickness (from 70 to 890 nm) on the electrical, structural and morphological properties are presented. The lowest resistivity obtained was 5×10⁻⁴ Ω cm with a Hall mobility of 13.7 cm²/Vs and a carrier concentration of 8.6×10²⁰ cm⁻³. These values were obtained by passivating the surface of the polymer with a thin silicon dioxide, so preventing the moisture and oxygen permeation inside the film.
DOI: 10.1016/j.surfcoat.2003.10.025

Abstract
Transparent and conductive high preferential c-axis oriented ZnO thin films doped with Al have been prepared by sol–gel method using zinc acetate and aluminium chloride as cations source, 2-methoxiethanol as solvent and monoethanolamine as sol stabilizer. Film deposition was performed by dip-coating technique at a withdrawal rate of 1.5 cm min⁻¹ on Corning 1737 glass substrate. The effect of dopant concentration, heating treatment and annealing in reducing atmosphere on the microstructure as well as on the electrical and optical properties of the thin films is discussed. The optical transmittance spectra of the films showed a very good transmittance, between 85 and 95%, within the visible wavelength region. The minimum resistivity of 1.3×10⁻³ Ω cm was obtained for the film doped with 2 wt.% Al, preheated at 400 °C and post-heated at 600 °C, after annealing under a reduced atmosphere of forming gas.
DOI: 10.1016/j.surfcoat.2003.10.112

Abstract
In this work a new methodology to stabilize the perovskite phase in (1−x)Pb(Zn_1/3Ta_2/3)O₃xPbTiO₃ ((1−x)PZTa-xPT) (x = 0.00−0.80) ceramics is presented. This approach combines the maximization of the crystalo−chemical and thermodynamics requirements and the optimization of the kinetics of the reaction of the perovskite phase formation by using a highly reactive PT nucleus. At the same time, and for comparison, PZTa-PT ceramics are prepared through a conventional mixed oxide procedure (columbite method). The effect of PT seeds is evaluated on the formation of the perovskite phase, and the microstructure and dielectric properties of PZTa-PT ceramics. Analysis of the phase formation process by DTA and XRD shows that PT seeds promote perovskite formation in the Pb(Zn_1/3Ta_2/3)O₃ system at a lower temperature and a lower PT content. A pure perovskite phase is obtained at x = 0.60 by the PT seeds method and only at x = 0.75 by the mixed oxide method. Dense and homogeneous microstructures are observed for seeded ceramics. The dielectric permittivity maximum of 0.40PZTa-0.60PT seeded ceramics is 13 800, compared with 5800 for the ceramics prepared by the conventional columbite method.
DOI: 10.1021/cm030592v

Abstract
A modification of the methoxyethanol-based sol–gel route used for depositing high-quality PbZr_0.52Ti_0.48O₃ (PZT) films at low temperature is reported. The modification consists of multiple distillations of Pb precursor after dissolving in 2-methoxyethanol and increasing the pyrolisis temperature after individual layer deposition. In addition, a large amount of PbO excess (20%) is used to maintain the stoichiometry of PZT films. As a result, the films processed at 500 °C possess a dielectric permittivity of ~1900, a remanent polarization of ~30 μC/cm² and a coercive field of ~60 kV/cm. The crystallization mechanism is discussed along with the possible applications of such films in microelectromechanical systems.
DOI: 10.1016/j.tsf.2003.10.104

Abstract
This paper presents preliminary results on Al doped ZnO thin films prepared by the sol-gel method. The thin films were produced by a dip-coater technique on glass substrate, using zinc acetate dihydrate, aluminium chloride hexahydrate, 2-methoxyethanol and monoethanolamine as raw materials. The ZnO thin films were analysed by XRD, Hall effect and SEM measurements. In order to determine the influence of the thermal treatments on the film properties, a set of four different heat treatments (atmosphere and temperature) were studied. All the films are polycrystalline presenting a crystallographic c-axis orientation (002) perpendicular to the substrate. The best results were obtained for films pre-heated at 400 °C and post-heated for 1 hour in air at 600 °C, after annealing under a reduced atmosphere of forming gas, where a resistivity of 3.9 x 10^-3 Omegacm, a Hall mobility of 34.1 cm²/Vs, a carrier concentration of 4.7 x 10¹⁹ cm^-3 and an optical transmittance of 90% were achieved.
DOI: 10.4028/www.scientific.net/MSF.455-456.16

Abstract
The effect of materials processing on structural and low-frequency dielectric properties of SrTiO₃ (ST) ceramics doped with MgO is studied in this work. Samples prepared with agate milling media show negligible solubility of MgO in ST. Instead, MgO was present in a SiO₂ rich phase at the grain boundaries. For some compositions containing this phase, a dielectric permittivity peak was present at low temperatures associated with an extra Raman vibrational mode. In contrast, samples prepared with teflon pots and ZrO₂ media exhibit a higher solid solubility limit of Mg in ST, absence of second phase at the grain boundaries and no dielectric anomaly at low temperatures for the same batched compositions.
DOI: 10.4028/www.scientific.net/MSF.455-456.40

Abstract
This work deals with the preparation of seeded PZT(52/48) thin films on Pt/Ti/SiO₂/Si substrates, utilizing PbTiO₃ and BaTiO₃. The comparison of the effect of the different types of perovskite crystalline seeds (BT, PT and PZT) on the perovskite phase crystallization, preferred orientation and electric properties of PZT thin films. The data show that phase formation process is less affected by the nature of the used seeds than the texture and electric response of the films. BT seeded films show higher dielectric constant than PZT and PT seeded films and are promising for dynamic random access memory applications, while the PZT ones show the superior ferroelectric properties, which are suitable for non-volatile ferroelectric random access memory applications.
DOI: 10.4028/www.scientific.net/MSF.455-456.50

Abstract
This work presents a study performed on several Au contacts deposited by evaporation on oxide free and oxidised (5-20 Angstrom of oxide) a-Si:H surfaces. The characterisation of the films was performed on as deposited, aged and annealed at 150 °C structures. SIMS and RBS measurements show that the Au diffuses very easily on oxide free a-Si:H surfaces, even at room temperature, resulting in the formation of an oxide at the device surface that acquires a blue col our instead of the gold colour of the contacts. This was also visible in the SEM pictures of the cross section of the structures produced and on the changes of the surface morphology observed by AFM measurements. On the other hand, when the Au is deposited on oxidised a-Si:H surfaces, the results show that the oxide prevents the Au from diffusing and the nature of the contact is preserved. That is, better rectifying and stability performances are obtained in MIS like structures than in Schottky structures.
DOI: 10.4028/www.scientific.net/MSF.455-456.96

Abstract
The Effect of Mn incorporation into perovskite B-site lattice of SrTiO₃ ceramics on structural and low frequency dielectric properties is studied in this work. Lattice parameter and grain size decreases with Mn content increasing. Mn doping reduces dielectric permittivity value and drives the system away from ferroelectric instability.
DOI: 10.1080/00150190490454620

Abstract
Dielectric response of two types of nominally pure hot-pressed PbZrO₃ ceramics (PZ1 and PZ2) of similar density (97–98%) was studied in the 1 MHz–1 GHz and far infrared frequency ranges in a wide temperature interval. While the far infrared spectra of both ceramics did not significantly differ from that of the crystal and the permittivity of PZ1 appeared to be comparable to that of the crystal, the permittivity of PZ2 was much lower. This reduction was particularly drastic (of about four times) on approaching the antiferroelectric phase transition from the paraelectric phase. We succeeded to explain this effect using a brick-wall model assuming nano-cracks development along some of the grain boundaries in PZ2 in agreement with SEM observations and unusual mechanic fragility of this ceramics. Our estimates show that even small volume fraction (3.
DOI: 10.1080/00150190490423589

Abstract
Strontium bismuth tantalate (SBT) ultrathin films with thickness about 40 nm have been prepared by a chemical solution deposition (CSD) method based on the synthesis of a Ta-glycolate derivative. Layers of the precursor solution diluted with 2-ethyl-1-hexanol were spin-coated onto Pt/TiO₂/SiO₂/(100)Si substrates. Crystallisation was carried out in oxygen at 650 °C by Rapid Thermal Processing (RTP). Topography of the films was observed by Scanning Force Microscopy (SFM). The piezoresponse mode of the SFM equipment was used to perform the nanoscale observation of the ferroelectric domain structure of the SBT ultrathin films and to measure piezoelectric hysteresis loops. The macroscopic ferroelectric response was measured on capacitors prepared after the deposition on the film surfaces of top platinum electrodes of ∼0.05 mm² of area.
DOI: 10.1016/S0955-2219(03)00227-9

Abstract
Sintered targets of Nb⁵⁺ doped PZT (65/35) (rhombohedral phase) were used in a pulsed laser deposition process to produce, in a single step, highly oriented ferroelectric thin films onto Pt (111)/TiO₂/SiO₂/Si substrates for electrical applications. The doping influence of 1% mol Nb on the crystalline phase formation and the resulting ferroelectrical and photoelectrical properties of the deposited films were investigated. The characterization was performed using X-ray diffraction, P–E hysteresis loop and photoelectric measurements. Maintaining the same composition PZTN (65/35/1), a comparison with bulk materials and thin films produced by sol-gel technique is also performed. The presented results give some indications about a possible existence of a “dead-layer” in the as-deposited films.
DOI: 10.1016/S0955-2219(03)00403-5