Showing papers in "Japanese Journal of Applied Physics in 2004"
TL;DR: In this article, GaN-nanocolumn-based InGaN/GaN multiple quantum disk (MQD) light-emitting diodes (LEDs) with a novel columnar structure were fabricated on n-type (111) Si substrates.
Abstract: GaN-nanocolumn-based InGaN/GaN multiple quantum disk (MQD) light-emitting diodes (LEDs) with a novel columnar structure were fabricated on n-type (111) Si substrates. The n-GaN and InGaN/GaN MQD active region had isolated columnar structures, while the diameters were gradually increased in the p-GaN region by controlling the growth conditions. Consequently, the nanocolumn LED had a continuous surface without chasms. This novel structure enables p-type electrodes to be fabricated by the conventional method on top of nanocolumn devices while keeping the superior optical properties of the isolated nanocolumn active region. The nanocolumn LED showed clear rectifying behavior with a typical turn-on voltage of 2.5–3.0 V at room temperature. Electroluminescence was observed through semitransparent electrodes with various emission colors from green (530 nm) to red (645 nm).
400 citations
TL;DR: In this article, the authors measured the largest ever measured in ferroelectrics and obtained a well-saturated remarkably giant saturation polarization of 158 µC/cm2 and a remanent polarization of 146 µC /cm2 for a maximum applied voltage of 20 V at 90 K.
Abstract: Ferroelectric BiFeO3 thin films have been deposited on Pt/TiO2/SiO2/Si substrate by pulsed-laser deposition. From the X-ray diffraction analysis, the BiFeO3 thin film consists of perovskite single-phase, and the crystal structure shows the tetragonal structure (c/a = 1.018) with a space group P4mm. It is obtained that the BiFeO3 thin film shows a well-saturated remarkably giant saturation polarization of 158 µC/cm2 and a remanent polarization of 146 µC/cm2 for a maximum applied voltage of 20 V at 90 K. These values of polarization are largest ever-measured in ferroelectrics.
331 citations
TL;DR: In this paper, the authors investigated the capability of harvesting electrical energy from mechanical vibrations in a dynamic environment through a "cymbal" piezoelectric transducer.
Abstract: In this study, we investigated the capability of harvesting the electrical energy from mechanical vibrations in a dynamic environment through a "cymbal" piezoelectric transducer. Targeted mechanical vibrations lie in the range of 50–150 Hz with force amplitude in the order of 1 kN (automobile engine vibration level). It was found that under such severe stress conditions the metal–ceramic composite transducer "cymbal" is a promising structure. The metal cap enhances the endurance of the ceramic to sustain high loads along with stress amplification. In this preliminary study, the experiments were performed at the frequency of 100 Hz on a cymbal with 29 mm diameter and 1 mm thickness under a force of 7.8 N. At this frequency and force level, 39 mW power was generated from a cymbal measured across a 400 kΩ resistor. A DC–DC converter was designed which allowed the transfer of 30 mW power to a low impedance load of 5 kΩ with a 2% duty cycle and at a switching frequency of 1 kHz.
328 citations
TL;DR: In this article, a magneto-resistance (MR) ratio of 88% at T = 293 K was reported for epitaxial magnetic tunnel junctions (MTJ), the highest value yet reported.
Abstract: We fabricated fully epitaxial Fe(001)/MgO(001)/Fe(001) magnetic tunnel junctions (MTJs) and observed a magneto-resistance (MR) ratio of 88% at T = 293 K (146% at T = 20 K), the highest value yet reported. The origin of the high MR ratio is not the diffusive tunneling of Julliere's model but the coherent spin-polarized tunneling in epitaxial MTJs, in which only the electrons with totally symmetric wave functions with respect to the barrier-normal axis can tunnel. The bias-voltage dependence of the MR was very small, resulting in a high output voltage of 380 mV. This high voltage will help overcome problems in the development of high-density magnetoresistive random-access-memory (MRAM).
287 citations
TL;DR: In this paper, the absolute photoluminescence (PL) quantum efficiency (ηPL) of organic solid-state thin films using an integrating sphere was accurately measured.
Abstract: We accurately measured the absolute photoluminescence (PL) quantum efficiency (ηPL) of organic solid-state thin films using an integrating sphere. We particularly measured the ηPL of conventional organic materials used in organic light emitting diodes, such as a tris(8-quinolionolato)aluminum(III) complex (Alq3), and a 2 wt%-fac-tris(2-phenylpyridyl)iridium(III):4,4'-bis(carbazol-9-yl)-2,2'-biphenyl [Ir(ppy)3:CBP] co-deposited film. Alq3 and Ir(ppy)3:CBP showed a ηPL=20±1% and 97±2%, which corresponded well to external electroluminescence efficiency using these materials. We also measured their transient PL decay and determined the radiative rate constants with their ηPL.
235 citations
TL;DR: In this paper, the authors demonstrate the construction of reasonably long and non-polarization changing photonic fiber waveguide using Teflon which is a readily available and highly flexible material.
Abstract: We demonstrate the construction of reasonably long and non-polarization changing photonic fiber waveguide using Teflon which is a readily available and highly flexible material. Due to its relatively low loss coefficient, the possibility of preparing longer photonic fiber waveguide, which has the potential of guiding intense THz radiation, can be easily attained.
231 citations
TL;DR: In this paper, the authors measured the refractive index, extinction coefficient, and absorption coefficient of the explosive C-4 by THz time-domain spectroscopy and examined its applicability to detecting C4 in mails.
Abstract: We have measured the refractive index, extinction coefficient, and absorption coefficient of the explosive C-4 by THz time-domain spectroscopy and examined its applicability to detecting C-4 in mails. The explosive C-4, which is used in almost all mail-bomb terrorist activities, shows six THz bands in the frequency region from 5 to 90 cm-1 (150 GHz–2.7 THz). The 26.9 cm-1 band is very strong and can be used as a fingerprint of C-4. We confirmed that the THz absorption spectrum of C-4 hidden inside an envelope coincides essentially with that of C-4 itself. We also examined the applicability of the THz reflection spectroscopy to C-4 detection by calculating the reflectance spectra. Our results demonstrate that the THz techniques are very promising for counterterrorism against C-4 mail bombs.
217 citations
TL;DR: In this paper, the sinterability and electrical properties of KNN ceramics were investigated as a function of K4CuNb8O23 (KCN) concentration.
Abstract: Dense (K,Na)NbO3 (KNN)-based ceramics were developed by optimizing the sintering conditions with newly developed K4CuNb8O23 (KCN) as a sintering aid. The sinterability and electrical properties of KNN ceramics were investigated as a function of KCN concentration. The density of KNN ceramics increased monotonically with increasing the KCN contents, and reached the highest value of 4.40 g/cm3 with the addition of 0.5 mol% KCN. This is due to the formation of liquid phase, which significantly promotes the densification of KNN ceramics. The Curie temperature (Tc) of pure KNN ceramics was 420°C and decreased with increasing the KCN content. With the addition of 0.5 mol% KCN, planar mode electromechanical coupling factor (kp) and mechanical quality factor (Qm) of KNN ceramics also reached the highest values of 0.39 and 1200, respectively. The KNN ceramics prepared with 0.5 mol% KCN exhibited a large field-induced strain of 0.09% at 40 kV/cm and the piezoelectric constant d33 of 180 pm/V.
214 citations
TL;DR: In this article, BaTiO3 diffuses into the lattice of (Na 0.5K0.5)NbO3 to form a solid solution, in which orthorhombic symmetry changes to tetragonal symmetry at x≈0.06, and cubic symmetry changes at x=0.20 or higher.
Abstract: (Na0.5K0.5)NbO3 with 0–20 mol% BaTiO3 has been prepared following the conventional mixed oxide process. High-density samples were obtained through the addition of BaTiO3 into (Na0.5K0.5)NbO3 because of an increase in grain size. X-ray diffraction analysis revealed that, during sintering, all of the BaTiO3 diffuses into the lattice of (Na0.5K0.5)NbO3 to form a solid solution, in which orthorhombic symmetry changes to tetragonal symmetry at x≈0.06, and tetragonal symmetry changes to cubic symmetry at x=0.20 or higher. It was found that the samples with a low content of BaTiO3 exhibit relatively good ferroelectric and piezoelectric properties. For 0.98(Na0.5K0.5)NbO3-0.02 BaTiO3 ceramics, the remanent polarization (Pr) is 7.5 µC/cm2 with a coercive field (Ec) of 12 kV/cm. The piezoelectric constant d33 reaches 104 pC/N. The electromechanical coupling coefficients of the planar mode kp and the thickness mode kt reach ~29% and ~38%, respectively. Our results show that (Na0.5K0.5)NbO3-BaTiO3 is a good lead-free piezoelectric ceramic.
210 citations
TL;DR: In this article, the authors further investigated the performance enhancement with SiGe in the δp+ layer and showed that the subthreshold swing of the vertical tunnel FET is not limited to the theoretical value of 60 mV/dec at room temperature.
Abstract: The metal–oxide–semiconductor (MOS)-based vertical tunnel field effect transistor (FET) on silicon has been proposed earlier and which showed gate-controlled band-to-band tunneling from the valence band in the heavily doped δp+ layer at source to the conduction band in the inversion channel. In this work, using 2D computer simulation, we further investigate the device performance enhancement with SiGe in the δp+ layer. On-current as well as threshold voltage are seen to improve considerably and meet the roadmap technology requirements. We also show that unlike the conventional MOSFET, the subthreshold swing of the vertical tunnel FET is not limited to the theoretical value of 60 mV/dec at room temperature.
210 citations
TL;DR: The orthorhombic structure of (Na 0.5K0.5)NbO3 (NKN) ceramics was maintained when ZnO was added as discussed by the authors.
Abstract: The orthorhombic structure of (Na0.5K0.5)NbO3 (NKN) ceramics was maintained when ZnO was added. NKN ceramics have a porous microstructure and dissolve when they are exposed to water. However, as ZnO was added, a dense microstructure was developed and deliquescence was not observed. The mechanical quality factor (Qm) and coercive field (Ec) increased with the addition of ZnO, indicating that ZnO acted as a hardener in the NKN ceramics. The dielectric constant (eT3/eo), piezoelectric constant (d33) and electromechanical coupling factor (kp) increased when a small amount of ZnO was added, which might be due to the increase in density. The good dielectric and piezoelectric properties of eT3/eo = 500, d33 = 121 and kp=0.4 were obtained for the NKN ceramics with 1.0 mol% ZnO.
TL;DR: In this article, an arrayed-waveguide-grating (AWG) demultiplexer using Si photonic wire waveguides, for the first time, was demonstrated.
Abstract: We demonstrated an arrayed-waveguide-grating (AWG) demultiplexer using Si photonic wire waveguides, for the first time. We designed and fabricated an AWG of 110 ×93 µm2 size on a silicon-on-insulator substrate. The demultiplexing function was observed in the wavelength range of 1.50–1.57 µm with a channel spacing of ~6 nm and a free spectral range of > 90 nm. A narrower channel spacing of 1 nm is possible in an area of ~(500 µm)2, using an optimization of arrayed waveguides and slab waveguides.
TL;DR: In this article, the growth processes of hydrogenated amorphous silicon (a-Si:H) and microcrystalline silicon (µc-Si-H) from SiH4 and H2/SiH4-glow discharge plasmas are reviewed.
Abstract: Growth processes of hydrogenated amorphous silicon (a-Si:H) and microcrystalline silicon (µc-Si:H) from SiH4 and H2/SiH4-glow discharge plasmas are reviewed. Differences and similarities between µc-Si:H and a-Si:H growth reactions in the plasma and on the film-growing surface are discussed, and the nucleus-formation process followed by the epitaxial-like crystal growth process is explained as being processes unique to µc-Si:H. The governing reaction of dangling-bond-defect density in the resulting a-Si:H and µc-Si:H films is also discussed in order to obtain a clue to improve the optoelectronic properties of these materials to enable device applications, particularly to thin-film silicon-based solar cells. Material issues concerning the realization of low-cost high-efficiency solar cells are described, and finally, recent progress in those issues is presented.
TL;DR: In this article, temperature-insensitive eye-opening under 10-Gb/s direct modulation of 1.3-µm p-doped quantum-dot lasers without using any current adjustments was demonstrated.
Abstract: We demonstrate temperature-insensitive eye-opening under 10-Gb/s direct modulation of 1.3-µm p-doped quantum-dot lasers without using any current adjustments. The lasers show a 6.5-dB extinction ratio between 20°C and 70°C. An active region consisting of ten quantum-dot layers with p-type doping enabled this highly temperature-stable dynamic performance, which was much superior to conventional 1.3-µm quantum-well lasers. These results make it possible to use uncooled 1.3-µm quantum-dot lasers without any current adjustments.
TL;DR: In this paper, a novel technique for time-domain attenuated total reflection spectroscopy in the terahertz (THz) frequency region is presented, which can be used to access samples with various shapes and optical properties without changing the optical setup.
Abstract: We present a novel technique for time-domain attenuated total reflection spectroscopy in the terahertz (THz) frequency region. The advantage of this technique is that it can be used to access samples with various shapes and optical properties without changing the optical setup. The technique is applied to determine the complex dielectric constants in InAs and distilled liquid water.
TL;DR: In this article, step-controlled epitaxy by using off-axis SiC {0001} substrates to grow high-quality epitaxial layer is explained in detail, which easily makes polytype replication of SiC at rather low temperatures.
Abstract: Technological breakthroughs in growth control of SiC are reviewed. Step-controlled epitaxy by using off-axis SiC {0001} substrates to grow high-quality epitaxial layer is explained in detail. The introduction of substrate off-angles brings step-flow growth, which easily makes polytype replication of SiC at rather low temperatures. Off-angle dependence, rate-determining processes, and temperature dependence of growth rate are discussed. Prediction, whether step-flow growth or two-dimensional nucleation does occur, is given as a function of off-angle, growth temperature, and growth rate. Optical and electrical properties of undoped epitaxial layers are characterized. Impurity doping during the growth is explained. Recent progresses in peripheral technologies for realization of power electronic devices, such as bulk growth, epitaxial growth, ion implantation, MOS interface, ohmic contacts, are introduced. Finally application to high-power electronic devices is briefly described.
TL;DR: In this article, a low loss elliptical intersection of Si photonic wire waveguides on a silicon-on-insulator substrate was fabricated, achieving an insertion loss of less than 0.1 dB at a wavelength of 1.55 µm.
Abstract: We fabricated a low loss elliptical intersection of Si photonic wire waveguides on a silicon-on-insulator substrate. An insertion loss of less than 0.1 dB was achieved at a wavelength of 1.55 µm. The experimental loss characteristic closely agreed with the theoretical one. We also used this intersection as a suspension of an air-bridge-type waveguide and evaluated a low loss characteristic similar to that mentioned above.
TL;DR: In this article, the proton dynamics of poly(4-hydroxystyrene) (PHS) films were investigated using Coumarin 6 (C6), and acid density was 0.022 nm-3 at the exposure dose of 10 µC cm-2 (75 keV electron beam).
Abstract: The proton dynamics of poly(4-hydroxystyrene) (PHS) films were investigated using Coumarin 6 (C6). The acid density was 0.022 nm-3 at the exposure dose of 10 µC cm-2 (75 keV electron beam). The absorption intensity of C6 proton adducts was saturated at a certain concentration of C6, indicating an almost complete addition of protons at this C6 concentration. Protons can move in PHS films near C6 molecules even at room temperature. Also, the absorbed dose was estimated using 60Co γ-rays. The acid yield can be well explained by an acid generation model involving the ionization of a base polymer.
TL;DR: In this paper, a UV-laser diode was constructed on low-dislocation-density AlGaN. The combination of a low-temperature-deposited AlN interlayer technology and heteroepitaxial lateral overgrowth yielded crack-free and partially low-dislocated-density ALGaN on a grooved GaN substrate.
Abstract: We demonstrated a UV-laser diode grown on low-dislocation-density AlGaN. The combination of a low-temperature-deposited AlN interlayer technology and heteroepitaxial lateral overgrowth yielded crack-free and partially low-dislocation-density AlGaN on a grooved GaN substrate. A ridge waveguide was fabricated in the low-dislocation-density region. The lasing wavelength under pulsed current injection at room temperature was 350.9 nm, which is the shortest wavelength ever reported.
TL;DR: In this article, the physical properties of high birefringence isothiocyanato biphenyl-bistolane liquid crystals were evaluated and a eutectic mixture based on those compounds was formulated and its physical properties evaluated.
Abstract: We have designed, synthesized, and evaluated the physical properties of some high birefringence (Δn) isothiocyanato biphenyl-bistolane liquid crystals. These compounds exhibit Δn~0.7–0.8 at room temperature and wavelength λ=633 nm. Laterally substituted short alkyl chains and fluorine atom eliminate smectic phase and lower the melting temperature. The moderate melting temperature and very high clearing temperature make those compounds attractive for eutectic mixture formulation. A eutectic mixture based on those compounds was formulated and its physical properties evaluated. The simulated absorption spectra agree reasonably well with the measured results.
TL;DR: In this article, a [100]-oriented BaSi2 multidomain epilayers were grown on Si(111) substrates by molecular beam epitaxy (MBE) using a BaSiSi2 epitaxial template formed by reactive deposition epitaxy.
Abstract: We have grown [100]-oriented BaSi2 multidomain epilayers on Si(111) substrates by molecular beam epitaxy (MBE) using a BaSi2 epitaxial template formed by reactive deposition epitaxy (RDE). The [100]-oriented BaSi2 films were obtained over a wide temperature range from 450 to 700°C: The optimum growth temperature was about 600°C at which the integrated intensity of X-ray diffraction peak was maximum and the full width at half maximum (FWHM) was minimum. X-ray pole figure measurements revealed that there were three epitaxial variants of [100]-oriented BaSi2 due to the three-fold symmetry of the Si(111) surface.
TL;DR: In this article, the authors have succeeded in growing multiwall carbon nanotubes (MWNTs) with low-resistance ohmic contacts to titanium electrodes by hot-filament chemical vapor deposition (HF-CVD) using a nickel catalyst layer on a titanium electrode.
Abstract: We have succeeded in growing multiwall carbon nanotubes (MWNTs) with low-resistance ohmic contacts to titanium electrodes by hot-filament chemical vapor deposition (HF-CVD) using a nickel catalyst layer on a titanium electrode. The contact resistance of the sample with nickel/titanium electrodes was two orders of magnitude smaller than that of the sample with nickel catalyst electrodes without titanium. We assumed that the low-resistance ohmic contact was achieved by forming titanium carbide (TiC) during the growth at the MWNT/titanium electrode interface. Moreover, we have demonstrated the growth of vertically aligned bundles of MWNTs, which were end-bonded to the lower titanium electrodes, selectively in via holes. We believe this is the first report of such simultaneous formation of MWNTs and their end-bonded low-resistance ohmic contacts, and its first trial application to carbon nanotube (CNT) vias for future ULSI interconnects.
TL;DR: In this article, a new class of diluted magnetic semiconductors based on CaO without transition metal elements was proposed and the electronic structure and the magnetic properties of B-, C- or N-doped CaO were calculated by using the Korringa-Kohn-Rostoker method within the local spin density approximation.
Abstract: We propose a new class of diluted magnetic semiconductors based on CaO without transition metal elements. The electronic structure and the magnetic properties of B-, C- or N-doped CaO are calculated by using the Korringa-Kohn-Rostoker method within the local spin density approximation. The substitutional and magnetic disorder is taken into account by the coherent potential approximation. It is found that B, C and N impurities show finite local magnetic moments in CaO at the oxygen-substitutional site. Moreover, these C- and N-doped CaO show the room-temperature ferromagnetism with half-metallic density of states.
TL;DR: In this article, the structural transformation of a ferromagnetic Mn1.07Co0.92Ge compound was studied by magnetization measurement in magnetic fields up to 13 T and powder X-ray diffraction measurement in fields of up to 5 T.
Abstract: The structural transformation of a ferromagnetic Mn1.07Co0.92Ge compound was studied by magnetization measurement in magnetic fields up to 13 T and powder X-ray diffraction measurement in fields up to 5 T. The Curie temperature is determined to be 275 K. At room temperature, the compound has a hexagonal Ni2In-type structure, and it transforms diffusionlessly into an orthorhombic TiNiSi-type structure at MS=210 K with hysteresis. The cell volume expands by 5.3% and the magnetic moment increases by 24% at MS, accompanied with this martensitic structural transformation. In addition, we confirmed for the first time that magnetic field induces the structural transformation in Mn1.07Co0.92Ge at the vicinity of MS.
TL;DR: In this paper, a theoretical investigation of the origin of substantial threshold voltage (Vth) shifts observed in p+poly-Si gate Hf-based metal insulator semiconductor field effect transistors (MISFETs), by focusing on the effect of oxygen vacancy (VO) formation in HfO2, was made.
Abstract: A theoretical investigation has been made of the origin of substantial threshold voltage (Vth) shifts observed in p+poly-Si gate Hf-based metal insulator semiconductor field effect transistors (MISFETs), by focusing on the effect of oxygen vacancy (VO) formation in HfO2. It has been found that VO formation and subsequent electron transfer across the interface definitely causes substantial Vth shifts, especially in p+poly-Si gate MISFETs. Moreover, the theory also systematically reproduces recent experimental reports that large flat band (Vfb) shifts are observed, even in intrinsic poly-Si gates, and that the Vfb shifts exhibit a high dependence on HfSiOx thickness.
TL;DR: In this paper, the authors employed the finite difference time domain (FDTD) method to numerically study the transmission characteristics of an H-shaped nano-aperture in a metal film in the optical frequency range.
Abstract: The finite-difference time-domain (FDTD) method is employed to numerically study the transmission characteristics of an H-shaped nano-aperture in a metal film in the optical frequency range. It is demonstrated that the fundamental TE10 mode concentrated in the gap between the two ridges of the H-shaped aperture provides a high transmission efficiency above unity and the size of the gap determines the sub-wavelength resolution. Fabry–Perot-like resonance is observed. Localized surface plasmon (LSP) is excited on the edges of the aperture in a silver film but has a negative effect on the signal contrast and field concentration, while aluminum acts similar to an ideal conductor if the film thickness is several times larger than the finite skin depth. In addition, it is shown that two other ridged apertures, C-shaped and bowtie-shaped apertures, can also be used to achieve a sub-wavelength resolution in the near field with a transmission efficiency above unity and a high contrast.
TL;DR: In this paper, a novel atomization system using surface acoustic wave (SAW) devices is described, where SAW radiates its energy into a liquid, if the liquid is loaded on the SAW propagating surface and various liquid motions, such as vibration, flow and droplet formation, due to interaction between SAW and liquid are called SAW streaming.
Abstract: In this paper, we describe a novel atomization system using surface acoustic wave (SAW) devices. The SAW radiates its energy into a liquid, if the liquid is loaded on the SAW propagating surface. The various liquid motions, such as vibration, flow and droplet formation, due to interaction between SAW and liquid are called SAW streaming. The liquid dynamics depends on the SAW input power. First, the relationships between input voltage to the SAW device and water dynamics are observed. For atomization, an input voltage larger than 30 VP-P is required. Second, a stable method of generating a mist is discussed. The thin liquid layer plays an important role in continuous mist generation. The fundamental properties, such as the angle and height of mist, are measured using a filter paper to keep a thin liquid layer on the surface. We also demonstrate the control of mist direction with an electrostatic field. Based on these fundamental experiments, a practical atomization system is designed and performed.
TL;DR: In this article, a method for the fabrication of a silicon on nothing (SON) structure with desired size and shape has been developed by using the empty-space-in-silicon (ESS) formation technique.
Abstract: A practical method for the fabrication of a silicon on nothing (SON) structure with the desired size and shape has been developed by using the empty-space-in-silicon (ESS) formation technique It was found that the SON structure could be precisely controlled by the initial shape and layout of the trenches The size of ESS is determined by the size of the initial trench The desired shapes of ESS, such as spherical, pipe-shaped and plate-shaped, can be fabricated by changing the arrangement of the initial trenches The fabricated SON region over ESS has excellent crystallinity adoptable for ultra-large-scale integrated circuit (ULSI) applications The SON structure would be a promising substrate structure for various manufacturing technologies, such as the micro-electro-mechanical system (MEMS), photonic crystals and waveguides
TL;DR: In this paper, the tetra-n-butyl ammonium bromide semi-clathrate hydrate ( TBAB hydrate) was used for separating gases from binary mixed gas systems.
Abstract: We used tetra-n-butyl ammonium bromide semi-clathrate hydrate, hereafter TBAB hydrate, as a tool for separating gases from binary mixed gas systems of methane+ethane, methane+propane, methane+hydrogen sulfide, methane+nitrogen, and carbon dioxide+hydrogen sulfide by growing the hydrate from 10 wt% TBAB aqueous solutions in a pressure vessel. TBAB hydrate has empty dodecahedral cages in the pure system. We found that small molecules such as methane, nitrogen, and hydrogen sulfide were selectively encaged during TBAB hydrate formation, probably because the dodecahedral cages are too small to incorporate large molecules such as ethane and propane. Furthermore, hydrogen sulfide was more readily encaged compared to the other small molecules; we argue that this was due to the very high solubility of hydrogen sulfide in water. We propose that gases with small molecular size and high solubility in water can be effectively separated using TBAB semi-clathrate hydrate.
TL;DR: In this article, high performance low temperature polycrystalline silicon (poly-Si) thin film transistors (TFTs) with large grains were created using diode pumped solid state (DPSS) continuous wave (CW) laser lateral crystallization (CLC), employing fabrication processes at 450°C.
Abstract: High performance low temperature polycrystalline silicon (poly-Si) thin film transistors (TFTs) with large grains were created using diode pumped solid state (DPSS) continuous wave (CW) laser lateral crystallization (CLC), employing fabrication processes at 450°C. Field-effect mobilities of 566 cm2/Vs for the n-channel and 200 cm2/Vs for the p-channel were obtained for a thick Si film (100–150 nm) on a 300×300 mm non-alkaline glass substrate. The high performance of the TFTs is attributed to the predominantly (100)-oriented very large grains. With a decreasing Si-film thickness, the grain size decreases, and the surface orientation of the grain changes from (100) to other orientations. These effects lead to reduced field-effect mobility with decreasing Si-film thickness, but it is easy to obtain a high field-effect mobility of over 300 cm2/Vs, even with a 50 nm thick Si film, without special processing techniques. A complementary metal oxide semiconductor (CMOS) ring oscillator was fabricated using a thin Si film 65 nm thick to demonstrate the high circuit performance of CLC poly-Si TFTs by applying the simplest CMOS process technology. A delay of 400 ps/stage at a gate length of 1.5 µm and a supply voltage of Vdd=5.0 (V) was produced on a large non-alkaline glass substrate utilizing a fabrication temperature of 450°C. This crystallization method will lead to the fabrication of high-performance and cheap Si-LSI circuits on large non-alkaline glass substrates.