A thin film transistor of the present invention includes a semiconductor thin film (8); a gate insulating film (7) formed on one surface of the semiconductor thin film (8); a gate electrode (6) formed to be opposite to the semiconductor thin film (8) through the gate insulating film (7); a source electrode (15) and a drain electrode (16) electrically connected to the semiconductor thin film (8); a source region; a drain region; and a channel region. The thin film transistor further includes an insulating film (9) formed on a peripheral portion corresponding to at least the source region and the drain region of the semiconductor thin film (8), and having a contact hole (10, 11) through which at least a part of each of the source region and the drain region is exposed wherein the source electrode (15) and the drain electrode (16) are connected to the semiconductor thin film (8) through the contact hole (10, 11).

Thin film transistor having an etching protection film and manufacturing method thereof

Garnets have the general formula of A3B2C3O12 and form a wide range of inorganic compounds, occurring both naturally (gemstones) and synthetically. Their physical and chemical properties are closely related to the structure and composition. In particular, Ce3+-doped garnet phosphors have a long history and are widely applied, ranging from flying spot cameras, lasers and phosphors in fluorescent tubes to more recent applications in white light LEDs, as afterglow materials and scintillators for medical imaging. Garnet phosphors are unique in their tunability of the luminescence properties through variations in the {A}, [B] and (C) cation sublattice. The flexibility in phosphor composition and the tunable luminescence properties rely on design and synthesis strategies for new garnet compositions with tailor-made luminescence properties. It is the aim of this review to discuss the variation in luminescence properties of Ce3+-doped garnet materials in relation to the applications. This review will provide insight into the relation between crystal chemistry and luminescence for the important class of Ce3+-doped garnet phosphors. It will summarize previous research on the structural design and optical properties of garnet phosphors and also discuss future research opportunities in this field.

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Ce3+-Doped garnet phosphors: composition modification, luminescence properties and applications.

Probing surface and interface morphology with Grazing Incidence Small Angle X-Ray Scattering

The word 'ceramics' is derived from the Greek keramos, meaning pottery and porcelain. The opaque and translucent cement and clay often used in tableware are not appropriate for optical applications because of the high content of optical scattering sources, that is, defects. Recently, scientists have shown that by eliminating the defects, a new, refined ceramic material — polycrystalline ceramic — can be produced. This advanced ceramic material offers practical laser generation and is anticipated to be a highly attractive alternative to conventional glass and single-crystal laser technologies in the future. Here we review the history of the development of ceramic lasers, the principle of laser generation based on this material, some typical results achieved with ceramic lasers so far, and discuss the potential future outlook for the field.

Ceramic laser materials

A method and apparatus for depositing a low dielectric constant film by reaction of an organosilicon compound and an oxidizing gas comprising carbon at a constant RF power level. Dissociation of the oxidizing gas can be increased prior to mixing with the organosilicon compound, preferably within a separate microwave chamber, to assist in controlling the carbon content of the deposited film. The oxidized organosilane or organosiloxane film has good barrier properties for use as a liner or cap layer adjacent other dielectric layers. The oxidized organosilane or organosiloxane film may also be used as an etch stop and an intermetal dielectric layer for fabricating dual damascene structures. The oxidized organosilane or organosiloxane films also provide excellent adhesion between different dielectric layers.

Plasma processes for depositing low dielectric constant films

Transparent polycrystalline YAG with nearly the same optical characteristics as those of a single crystal were fabricated by a solid-state reaction method using high-purity powders (>99.99 wt% purity). The average grain size and relative density of the 1.1 at.% ND:YAG ceramics obtained were about 50 {micro}m and 99.98%, respectively. An oscillation experiment was performed on a cw laser by the diode laser excitation system using the fabricated ceramics. The experimental results indicated an oscillation threshold and a slope efficiency of 309 mW and 28%, respectively. These values were equivalent or superior to those of the 0.9 at.% ND:YAG single crystal fabricated by the Czochralski method.

Fabrication and Optical Properties of High-Performance Polycrystalline Nd:YAG Ceramics for Solid-State Lasers

Polycrystalline, transparent YAG (Y{sub 3}Al{sub 5}O{sub 12}) ceramics were fabricated by a solid-state reaction method using high-purity Al{sub 2}O{sub 3} and Y{sub 2}O{sub 3} powders. The mixed powder compacts were sintered at 1,600 to 1,850 C for 5 h under vacuum. Optical transmittance in the region between the ultraviolet and infrared wavelengths for YAG ceramics (1 mm thick) sintered at 1,800 C was similar to that for a YAG single crystal.

Fabrication of Polycrystal line, Transparent YAG Ceramics by a Solid‐State Reaction Method

A neodymium-doped yttrium-aluminum garnet (Y{sub 3}Al{sub 5}O{sub 12}, YAG) (Nd:YAG) ceramic that contained 0.3--4.8 at.% neodymium additives and exhibited nearly the same optical properties as those of a single crystal was fabricated by a solid-state reaction method using high-purity powders. Although the integrated absorption intensity of the {sup 2}H{sub 9/2} + {sup 4}F{sub 5/2} bands simply increased as the neodymium concentration in the YAG ceramics decreased, the fluorescence intensity of the 2.4 at.% Nd:YAG ceramic was the strongest among Nd:YAG ceramics with various neodymium concentrations and a 0.9 at.% Nd:YAG single crystal. An oscillation experiment was performed on a continuous-wave (cw) laser with a diode-laser exciting system using those ceramics and the single crystal. The oscillation threshold and slope efficiency in that analysis were 309 mW and 28%, respectively, for the 1.1 at.% Nd:YAG ceramics and 356 mW and 40%, respectively, for the 2.4 at.% Nd:YAG ceramics. The lasing characteristics of the ceramics in the present work were superior to those of a 0.9 at.% Nd:YAG single crystal that was fabricated by the Czochralski (Cz) method.

Effects of Neodymium Concentration on Optical Characteristics of Polycrystalline Nd:YAG Laser Materials

Nd,Cr-codoped transparent YAG (Y{sub 3}Al{sub 5}O{sub 12}) ceramics with excellent optical properties were fabricated by a solid-state reaction method using Al{sub 2}O{sub 3}, Y{sub 2}O{sub 3}, Nd{sub 2}O{sub 3}, and Cr{sub 2}O{sub 3} powders of 99.99 wt% purity. The mixed powder compacts were sintered at 1,750 C for 20 h under vacuum and annealed at 1,400 C for 20 h in an oxygen atmosphere. The Nd,Cr-codoped YAG ceramics consisted of grain sizes ranging from 5 to 35 {micro}m and exhibited a pore-free structure. The optical transmittance of a 0.8 at.% Nd,0.4 at.% Cr:YAG ceramic at 1,000 nm was nearly equivalent to that of a 0.8 at.% Nd:YAG single crystal. In addition, the fluorescence intensity of the 0.8 at.% Nd,0.4 at.% Cr:YAG ceramic excited by a xenon lamp was double that of the 0.8 at.% Nd:YAG single crystal.

Synthesis of Nd3+,Cr3+‐codoped YAG Ceramics for High‐Efficiency Solid‐State Lasers

A Nd-doped HfO2-Y2O3 ceramic having excellent transmittance was synthesized by HIPing, using high-purity powders (>99.99 wt%) of Y2O3, Nd2O3, and HfO2. The mixed powder compacts of these powders were sintered at 1650°C for 1 h under vacuum and HIPed at 1700°C for 3 h under 196 MPa of Ar. The specimen after HIPing consisted of uniform grains measuring about 30 μm and having pore-free structure. The optical transmittance of 1 at.% Nd-doped 2.6 mol% HfO2-Y2O3 ceramics ranging between visible and infrared wavelength was almost equivalent or superior to that of a Nd:Y2O3 single crystal grown by the Verneuil method.

Kiichiro Kamata

Papers

Fabrication and Optical Properties of High-Performance Polycrystalline Nd:YAG Ceramics for Solid-State Lasers

Fabrication of Polycrystal line, Transparent YAG Ceramics by a Solid‐State Reaction Method

Effects of Neodymium Concentration on Optical Characteristics of Polycrystalline Nd:YAG Laser Materials

Synthesis of Nd3+,Cr3+‐codoped YAG Ceramics for High‐Efficiency Solid‐State Lasers

Synthesis of Transparent Nd-doped HfO2-Y2O3 Ceramics Using HIP