D.T. Amm

Lead zirconate titanate films by rapid thermal processing

Lead zirconate titanate films have been fabricated by a dc sputtering technique with a post deposition rapid thermal annealing treatment at 650 °C for 10 s. The films exhibited good structural, dielectric, and ferroelectric properties compared to conventional furnace‐annealed films. The measured dielectric constant and loss tangent at 1 kHz were 900 and 0.04 and the remanent polarization and coercive field values were 10 μC/cm2 and 23 kV/cm, respectively. No significant fatigue in polarization was observed in the films up to 1010 cycles of bipolar stress. The films were optically transparent and showed a linear electro‐optic (EO) effect after poling with an EO coefficient of 1.5×10 −11 m/V.

Fabrication of ultrathin metal oxide films using Langmuir–Blodgett deposition

Thin Y2O3 films have been fabricated using a Langmuir–Blodgett (LB) process. Uniform LB films of yttrium arachidate have been successfully deposited up to 200 layers. These films were found to decompose uniformly above 300 °C leaving a thin oxide layer. X‐ray diffraction, laser reflection, and Rutherford backscattering have been used to determine crystal structure and stoichiometry of the film before, during, and after thermal decomposition. This test system demonstrates the potential application of Langmuir–Blodgett deposition for inorganic oxide film fabrication of thicknesses ranging from 0.1 to 40 nm.

Fabrication of cadmium oxide thin films using the Langmuir-Blodgett deposition technique

Abstract Thin conducting cadmium oxide (CdO) films were fabricated from Langmuir-Blodgett Cd arachidate precursors through a combination of low temperature ultra-violet/ozone (UVO) decomposition and annealing treatments. The decomposition and oxidation of the UVO residue to CdO occurred between 220 to 300 °C, and was observed using in-situ laser reflectivity and resistivity measurements. The final CdO film resistivities were in the 104–105 Ω/ range, depending on annealing conditions. Atomic force microscopy revealed nanometre-scale surface roughness in the final film, which most likely resulted in the lower conductivity measured in the film as compared to bulk CdO fabrication techniques.

Langmuir-Blodgett deposition of yttrium arachidate

Abstract Langmuir-Blodgett films consisting of many monolayers of yttrium arachidate were deposited on Si(100) from a subphase concentration of 10 -5 M YCl 3 over a pH range of 4.0–6.9. The depositions were uniform with normal Y-type stacking and did not show detrimental rigidity effects normally associated with trivalent ions. The resultant film properties were characterized via the pressure-area isotherms and with Fourier transform IR spectroscopy, Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy studies. The data indicate that the metal is being incorporated into the arachidic acid predominantly as Y(OH) 2+ . A saturation areal density of (9.0 ± 0.5) × 10 15 Y cm -2 was measured for 50 layers of yttrium arachidate.

Integrated Piezoelectric and Pyroelectric Devices from Thin Film Ferroelectrics

Thin PZT films 1-4 μm in thickness prepared by sputtering or sol gel methods allow PZT films to be integrated with silicon technology to achieve piezoelectric or pyroelectric structures having small size or mass. Design criteria, materials and processing techniques for such devices are discussed, and the implementation of small size devices on silicon substrates is demonstrated. Factors of importance are the piezoelectric and pyroelectric characteristics achievable in the films, mechanical strength and fatigue, and the stability and compatibility of the films and electrodes with device fabrication procedures and operating conditions.

Decomposition of Langmuir-Blodgett films to form metal oxide layers

Abstract Ultraviolet/ozone (UVO) treatment is investigated as a processing step in the fabrication of metal oxide thin films from Langmuir-Blodgett (LB) precursor films. UVO processing was found to reduce LB films to metal carbonates at a rate of approximately 1 min per layer. Subsequent thermal treatment resulted in dense, uniform metal oxide thin films. The structure and composition of these films are studied ellipsometry, X-ray diffraction, and Rutherford backscattering spectrometry.

RBS analysis of Langmuir-Blodgett films

Abstract Rutherford backscattering spectrometry (RBS) has been used to characterize thin films of yttrium and erbium arachidate deposited on a silicon substrate by a Langmuir-Blodgett technique. RBS can measure film thickness as well as the stoichiometry. Beam effects do not influence these results at moderate beam currents and fluences, although the films visual appearance was very sensitive to beam exposure. Beam-induced hydrogen desorption is also expected, and evidence for this is presented at high doses. RBS has also been used to characterize LB films during thermal decomposition and to analyze the metal-oxide end products (Y 2 O 3 and Er 2 O 3 films). An example is also given where a mixed YBaCu-oxide film is deposited by this method.

Characterization of Lead Zirconate Titanate (PZT) - Indium Tin Oxide (ITO) Thin Film Interface

The interface between ultrathin sputtered lead zirconate titanate (PZT) films and a conductive electrode (indium tin oxide-ITO) is investigated. Structural and compositional changes at the PZT-ITO interface have been examined by surface analysis and depth profiling techniques of glancing angle X-ray diffraction, Rutherford backscattering (RBS), SIMS, Auger electron spectroscopy (AES), and elastic recoil detection analysis (ERDA). Studies indicate significant interdiffusion of lead into the underlying ITO layer and glass substrate with a large amount of residual stress at the interface. Influence of such compositional deviations at the interface is correlated to an observed thickness dependence in the dielectric properties of PZT films.

Yttrium oxide film deposition by a Langmuir-Blodgett processing technique and its incorpiration into oxide scales by substrate oxidation

Abstract Thin films (about 10 nm) of Y 2 O 3 have been deposited by a Langmuir-Blodgett processing technique onto a variety of substrates: type 304 stainless steel, low carbon steel, titanium, zirconium and silicon. The substrates were afterwards oxidized in air at 800, 1000 (304 steel), 400 (low C steel), 500 (Ti), 450 (Zr) and 1000 (Si) °C. The effects of the film on the oxide scale thickness and the interaction between Y 2 O 3 and the oxide of the substrate have been studied by ion backscattering. In stainless steel, the Y 2 O 3 film reduces the oxidation rate by orders of magnitude and Y is distributed throughout the oxide scalw (1–10 at.% level). In other substrates, the effect on oxidation rate was less pronounced, but changes in the visual appearance often took place. The Y 2 O 3 incorporation varied for the different substrates, and Y 2 O 3 remained as a surface film in the cases of Ti and Si. Such films exhibited good adherence and could not be removed by wiping. The potential use of metal oxide thin films for surface analysis standards and diffusion marker studies is discussed.

Order-disorder transitions of yttrium arachidate Langmuir-Blodgett films via ellipsometric anisotropies

Abstract Ellipsometric order-disorder transition studies have been performed on films of yttrium arachidate. Upon heating, the films were observed to undergo two optical transitions at 65°C and 100°C. At room temperature, the as-deposited films were found to be anisotropic, with indices of refraction of N x = 1.503±0.004 and N z = 1.554±0.004 and a layer spacing of 2.73±0.03 nm. Above 100°C the films were isotropic, with N = 1.440 ± 0.004 and a thickness of 3.13 ± 0.03 nm per original layer. Between 65°C and 100°C the films showed unusual behaviour. X-ray diffraction showed that the film maintains a strong layered structure when cooled from below 100°C. When cooled from above 100°C, X-ray peaks are greatly reduced. The films showed no desorption below 100°C.