摘要:

The central problem of the sensor design is a good thermal insulation of the P(VDF/TrFE) thin film from the read-out circuit. Two variations were examined - thin carrier membranes of SiO2/Si3N4produced through back etching and thick thermal insulating layers out of spin-coated polymers with via holes. Through simulation and measurements on single element sensors and linear arrays for both variants an optimal design could be established. Membrane sensors consisting of 1 μm P (VDF/TrFE) thin film deposited on a 0·65 μm thick membrane show within the frequency range of 10 Hz to 1 kHz comparatively higher values for responsivity and specific detectivity than insulating layer sensors. The insulating layer sensors have in the most favourable case a thermal cutoff frequency of about 100 Hz, below that the responsivity remains constant while the specific detectivity and NEP deteriorate again. The optimal layer thickness for the compound of BCB and P(VDF/TrFE) for a chopper frequency of about 100 Hz is at approximately 18…25 μm. The advantages of the design with insulating layer are however, that a filling factor of almost 100% independently of the pixel size is reachable and that very small pixels of about (50X50) μm2are realisable too.

ISSN:1058-4587    

DOI:10.1080/10584589508013574

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

High sensitive pyroelectric infrared (IR) sensors have been fabricated by using c-axis oriented La-modified PbTiO3(Pb1–xLaxTi1−x/4O3, PLT) thin films. The PLT thin films were deposited on (100)-cleaved MgO single crystal substrates by intermittent rf-magnetron sputtering method. The PLT thin films have high figures of merit for IR sensor without a poling treatment. High performance pyroelectric IR sensors (single element type and linear array type) were fabricated by using PLT (x=0·1, γ=5·5x10−8C/cm2K, ϵr=200) thin films. The sensors have remarkably high D* of 3–6x108cmHz1/2/W and very fast response. A new compact IR sensing system using the linear array sensor (8 elements) has been developed for a new type of room air-conditioner. This system can measure thermal distribution (8x64) by horizontal scanning of the vertical linear array. Image processing with neural network concept makes possible high-accuracy using a few data from the sensor elements. This sensing system provides ‘‘smart airconditioning'’to improve the comfortable control.

ISSN:1058-4587    

DOI:10.1080/10584589508013575

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The optical quality of sol-gel processed Pb(Zr,Ti)O3thin films has been investigated using spectrally and angularly resolved light scattering. Measurements were performed on a series of films of differing thicknesses, and the results were compared to the predictions of model calculations based upon scattering due to surface roughness, or due to variations of the dielectric constant within the volume of the film. The surface scattering model successfully reproduced many of the features of the observed light scattering. In contrast, the predictions of the volume scattering model differed substantially from the experimental data. In addition, the surface roughness spectrum obtained using atomic force microscopy was used to calculate the angularly resolved light scattering expected for one of the films. For angles greater than ∼20°, the predicted and experimentally determined light scattering were in close agreement. These results indicate that light scattering from these films is primarily due to surface roughness.

ISSN:1058-4587    

DOI:10.1080/10584589508013576

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

KNbO3, K(Ta,Nb)O3, KTaO3, and Ta2O5thin films have been grown by ion-beam sputter deposition. KNbO3has excellent nonlinear properties for second harmonic generation; however, high optical losses are still characteristic of these films. Several loss mechanisms, such as, high angle grain boundaries, twin domains, interface and surface scattering, and oxygen vacancies can all contribute to the high losses. In order to isolate the various mechanisms, amorphous Ta2O5films, epitaxial cubic KTaO3and tetragonal K(Ta,Nb)O3films were grown on MgO and Al2O3substrates subjected to post-deposition annealing treatments and various oxygen pressure conditions. The optical losses and refractive indices were observed to differ depending on the substrate surface and annealing treatments. Resonant scattering experiments were performed to analyze the oxygen composition. The optical properties of these oxide thin film systems are reported and the breakdown of the loss mechanisms is addressed.

ISSN:1058-4587    

DOI:10.1080/10584589508013577

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

PbTiO3-based ferroelectric films are attractive materials for passive and active waveguides due to their high refractive indices (> 2·0), small attenuation losses (1–6 dB/cm) and low processing temperatures (< 600C). A series of sol-gel derived La-doped PbTiO3 waveguides was prepared on Corning 7059 glasses. 0·5M precursor solutions of Pb1−x/100Lax/100Ti1−x/400O3 with × = 0, 5, 10, 15, 20, 25, 28, 30 and 32 were spincoated on the substrates and fired to 400C, 500C and 600C for 30 mins. XRD was used to determine the phase assembly present in the films as a funcion of La stoichiometry and firing temperature. The presence of La seemed to aid in achieving the formation of single-phase perovskite films. Transmission spectra obtained using a UV-Vis spectrometer provided information on band gap energies; and the spectra were used to calculate the refarctive indices and extinction coefficients based on the envelope method. The refractive index decreased and band gap increased with increasing La content in the films. The waveguiding properties and optical attenuation were studied by prism coupling using a HeNe laser and rutile prism. The optical losses are discussed with regard to composition (especially La content), phase assembly and microstructure of the films. Crystalline PLT 28 films exhibit attenuation loss as low as 1·4 dB/cm, which represent the lowest reported value for any sol-gel or sputtered PLZT film.

ISSN:1058-4587    

DOI:10.1080/10584589508013578

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Reflection ellipsometry and computational modeling are used to examine electro-optic (EO) effects in a PZT (30/70) thin film. The combined influences of thin film etalon effects, the optical configuration used to measure electro-optic changes in the PZT/electrode thin film stack, and incoherent scattering within the layer structure are found to significantly influence the corresponding intensity modulation under an ac field. The impact of these findings on design considerations for EO-based devices and the use of photometric ellipsometry to characterize these materials is discussed.

ISSN:1058-4587    

DOI:10.1080/10584589508013579

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Ferroelectric (FE) films constitute an important component of electro-optic devices; such films have been used for second harmonic generation, spatial light modulators and optical switches. FE films typically yield large values of linear and quadratic electro-optic coefficients. Most electric field induced birefringence measurements have been made with transverse electrodes, i. e. with light beam between poled electrodes. In the present study, an Ultimate Ellipsometer was used; a HeNe laser was directed perpendicularly through FE capacitors with applied voltages and the phase change monitored. The layout of this device is discussed in details.

ISSN:1058-4587    

DOI:10.1080/10584589508013580

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The capacitor requirements for Gbit-scale DRAMs are discussed in detail. The choice of SrTiO3thin films over a stacked RuO2/TiN structure for the 1 Gbit DRAM is explained, and particular emphasis is put on the necessity of a stacked capacitor structure and on the selection of a suitable electrode material.

ISSN:1058-4587    

DOI:10.1080/10584589508013581

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A process technique to integrate the sputter-deposited BST thin film into the DRAM is discussed. With some reconsiderations concerning the grain structure of the BST, the care of the electrode edge, the thermal stability of the capacitor characteristic, the upper dielectric of the capacitor and so on, the BST was successfully integrated into a capacitor TEG structure on a 9Mbits scale. By using the newly developed integration technique, a 4MDRAM was fabricated, exhibiting the normal bit function with a wide margin. After this, improvements on the thermal stability are needed by developing a barrier layer under the bottom Pt electrode that is more heat-resistant than currently achieved.

ISSN:1058-4587    

DOI:10.1080/10584589508013582

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The crystal structure and electrical properties of (Ba0·5Sr0·5)TiO3thin films deposited on various Pt-base electrodes by RF magnetron sputtering, have been investigated. Surface morphology and crystallinity of Pt films for bottom electrode changed with deposition temperature for Pt. The Pt films deposited at 400°C by sputtering have perfectly (111) preferred orientation and dense surface with hillock-free morphology. An 100nm BST film has a dielectric constant of 575 and a leakage current density at 2V of 1·8 × 10−7A/cm2. It is clear that the bottom electrodes are important in determining preferred orientation and electrical properties of BST thin films. With increasing film thickness of BST, the grain size of BST films gradually increased. Dielectric constant of the BST films deposited at 600°C also increased with increasing grain size. It was measured that the dielectric constant decreases from 758 to 348 with the grain size of 82–32nm in the BST films.

ISSN:1058-4587    

DOI:10.1080/10584589508013583

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor