We proposed a new type of Peltier device, and succeeded in the fabrication of the device, which we call a point-contact-type sandwich-structure (PCS). A micro-object can be cooled or heated using our fabricated device. The tip was cooled through the Peltier effect, and a tip temperature of -36.3°C was achieved at a current of 28 A. When current was reversed, the tip was heated and the maximum tip temperature was 251.5°C at a current of 20 A. The PCS Peltier device can be useful in medical treatment and bioelectronics.
Si-Si wafer direct bonding was performed by surface activation with Ar ion beam bombardment. The X-ray photoelectron spectroscopy (XPS) spectrum of the Si surface before and after the Ar ion beam bombardment was measured in situ to study the bonding condition quantitatively. The condition of the Ar ion beam bombardment gave the effect for the surface roughness, which was measured by Atom force microscope (AFM). The surface roughness is strongly related to the bonding. The roughness less than Ra=1 nm is necessary for the Si-Si wafer direct bonding.
A ruby capillary which is available as an industrial product for the wire bonding machines for the microelectronics has been adopted to focus ion beams passively for the first time. An Ar+ ion beam with a beam current density of 3×10-6 A•cm-2 at an energy of 4 keV has been found to penetrate steadily the ruby capillary and the behavior of the beam through the capillary has been investigated in details. It has been also found that a large amount of secondary electrons are generated when the ion beam hits the capillary and a negative bias should be applied to the Faraday cup to measure the ion beam current through the capillary though the positive ion beam is to be measured.
Quartz sensor measurements were performed on ammonia plasmas to analyze their gas phases. From the analysis using a quadrupole mass spectrometer, it was found that the main products formed in the ammonia plasmas in this study were nitrogen and hydrogen molecules in the ratio of 1:3. The quartz sensor can be used to measure the partial pressure of each gas in binary gas mixtures in ammonia plasmas if they consist of the binary gases of ammonia and a mixture of nitrogen and hydrogen in the ratio of 1:3. However, the results for the ammonia plasmas obtained by the Q-sensor measurement do not agree with those obtained from mass spectroscopy. This indicates that the results of quartz sensor measurements may include information on highly reactive chemical species in addition to that on nitrogen and hydrogen molecules.
I precisely measure the depth profiles of 50-200 keV P+ implanted into Si and SiO2 by secondary ion mass spectrometry (SIMS) and then best-fit the simulated profiles to the observed ones by taking adequate parameters of their stopping powers. Next, the phosphorus depth distributions in SiO2/Si plate and SiO2 powders for high-dose implantation are determined by Rutherford Backscattering spectroscopy (RBS) and SIMS, respectively. The phosphorus profiles derived from RBS and SIMS analysis are compared with those calculated by the extended SRIM to consider sputter-erosion, a swelling effect and composition change during the implantation. The simulated profiles are good agreement with observed profiles for high-dose phosphorus implantation with energy of 50-200 keV. Present simulation revealed the implantation energy dependence of threshold dose without phosphorus existence at the surface.
Effects of ultraviolet (UV) light irradiation on a polymer dry etching process have been investigated with the use of a low-energy mass-selected ion beam system. The effective etched depth of polymethylmethacrylate (PMMA) by CF3+ ion beam injection and/or UV light irradiation was evaluated from the decrement of PMMA film weight measured by a quartz crystal microbalance. A significant enhancement of the etched depth of PMMA was observed when a CF3+ ion beam was injected to PMMA substrate with UV light irradiation. The etched depth of PMMA during simultaneous irradiation of CF3+ ion beams and UV light was greater than the sum of those obtained from separate CF3+ ion beam or UV light irradiation processes.
An electron cyclotron resonance ion source (ECRIS) has been developed for a synthesis of endohedral metallofullerenes. The ECRIS has a traditional minimum-B magnetic field and an 8-10 GHz traveling wave tube (TWT) amplifier as a microwave source. C60 plasmas have been generated at the first experiment. Many broken fullerenes C58 and C56 are observed in fullerene ion beams. We investigated the fullerene ion beams against pressures in the ion source. From the results, these fullerene ion currents increase as the decrease of the pressure and the maximum current is 0.81 μA of C602+.
An organic field-effect transistor (OFET) was prepared with thin film fabricated by soluble pentacene as the semiconductor layer, polyimide thin film as the gate insulating layer, and Au as the drain, source and gate electrodes. The pentacene and polyimide thin films were fabricated by the cast and spin coat methods. The carrier mobility of the organic field-effect transistor was 1.2×10-2 cm2/Vs. The ON/OFF ratio was 3×102. As compared with the carrier mobility of OFET prepared by the evaporation method, their values were the same as that of the spin-coating method. However, the ON/OFF ratio obtained was lower. This indicates that it is either the leakage current in polyimide thin film that is large or it is that of the off-current of the pentacene thin film.
This paper describes the microfabrication of transparent thermoplastic plates, polymethyl-methacrylate, polycarbonate, and cyclic olefin polymer by an electron cyclotron resonance-reactive ion etching (ECR-RIE) system. The system was adopted for the microstructure with smooth surface and high-aspect ratio. The etching was carried out using O2/CF4 plasma. The etching conditions are set at 13.56 MHz high-frequency output of 100 W (self-bias voltage: -430 V--310 V) and the stage temperature of -15°C. We have examined the surface roughness and the optical properties at the range of process pressure 0.05-0.5 Pa. The surface roughness of etched substrates is below 20 nm and the average transmittance is over 98% at the process pressure of 0.05 Pa.
We have developed a Micro-Capillary-Array (MCA) Beam Doser in order to dose a collimated molecular beam. Whereas the response of the chamber pressure was fast in the dosage of N2, D2 and Ar, the pressure response to the NO dosage was slow with a delay of about 5 s. When gases pass through an MCA with a large length to radius ratio as a free molecular flow, they repeatedly collide with the MCA walls. It was found that gases that have a small residence time (τ) pass through the MCA without substantial delay. On the other hand, those with large τ reveal a delayed flow, and it takes a few seconds to attain a steady-state flow.
In order to obtain 3D mapping of the hydrogen distribution in solids in-situ, the nuclear reaction analysis (NRA) measurement has been carried out by using a tapered glass capillary to focus and introduce the incidence beam to the sample under atmosphere. A Y thin film covered with Pd was used for this measurement. In the N2 gas, hydrogen absorbed by the Y film was observed at a pressure up to 8×103 Pa. In the H2 gas and air, on the other hand, substantial γ-ray signals were observed at 15N energies of 6400~7200 keV, which obscured the signal originating from the Y sample. The origin of this signal is discussed.
Diamond-like Carbon (DLC) films were deposited on nickel sheets and tungsten tips by liquid-phase electrodeposition, and were investigated by using field emission scanning electron microscopy (FE-SEM), Raman spectroscopy and atom probe (AP). The surface morphology of the deposited films was observed by FE-SEM. It can be seen that the films were composed of small grains. Raman spectra of the films exhibited two broad peaks around 1200-1450 cm-1 called D-peak and 1500-1700 cm-1 called G-peak. By AP analysis, some hydrocarbon ions were detected. It indicates that the films were composed by not only carbon but also hydrogen.
Multi-walled carbon nanotube-filled polytetrafluoroethylene (CNT-PTFE) film was fabricated and its field emission properties were investigated. The surface roughness of the CNT-PTFE was larger than that of the PTFE film without CNT. The emission current followed the Fowler-Nordheim relationship. The fluctuation of the emission current was ±0.025 mA or lower for the average emission current of 0.35 mA, which is corresponding to the fluctuation ratio of 7%.
A 150 nm-thick aluminum-doped transparent conducting zinc oxide (AZO) films and a 100 nm-thick ZnO buffer layer have been deposited on Cycloolefin Polymer (COP) substrates with laser energy densities of 1.0~2.5 J/cm2 by pulsed laser deposition (PLD) using ArF excimer laser (λ=193 nm). As a result, the lowest resistivity of 2.77×10-4 Ω•cm was obtained at laser energy density of 1.0 J/cm2.
For improvement of a fabrication process at low temperature of transparent conducting zinc oxide films, gallium-doped zinc oxide (GZO) films have been deposited on glass substrates at room temperature by pulsed laser depositon using Nd:YAG laser (FHG of λ=266 nm, 1.0 J/cm2), and then annealed by irradiating pulsed laser beams of SHG (λ=532 nm, 40~60 mJ/cm2), THG (λ=355 nm, 20~60 mJ/cm2) and FHG (λ=266 nm, 20~40 mJ/cm2) at room temperature. As a result, the resisivity was improved from 8.45×10-4 to 6.27×10-4 Ω•cm for the films annealed at FHG of energy density of 40 mJ/cm2 (improvement effect of 23.2%)
Tungsten oxide/bismuth oxide composite thin films prepared by multi target radio frequency (RF) reactive sputtering were investigated. X-ray diffraction measurements of the crystallinity of thin films prepared at room temperature revealed amorphous structure. Although the compositional ratio of composite thin films prepared at 50 W and 75 W of the RF power of the Bi target was almost the same, those prepared at 50 W were transparent, and had a much smaller optical absorption coefficient at 3.0 eV than those prepared at 75 W. Bi 4f spectra of these thin films were measured by X-ray photoelectron spectroscopy, and were analyzed by full width at half maximum of Bi 4f7/2 peaks. As a result, the transparency is thought to be caused by the change of bonding state of Bi-O. Electrochromic properties of the composite thin films were also measured in 0.1 M H2SO4. Coloration of composite thin films prepared at 20 W of the RF power of the Bi target changed reversibly from transparent to black and brown.
Pt1-xPdxO thin films were prepared by rf reactive co-sputtering of Pt and Pd target to obtain high quality PtO thin films. To reveal the effect of free carrier absorption caused by high carrier concentration in PtO thin films, its electrical properties and optical properties were measured and analyzed. In the result, quantities of absorption coefficient in visible to near ultraviolet light region were different between PtO films because of the difference of each carrier concentration. Despite this, these absorption coefficients become nearly the same quantities when subtraction of free-carrier absorption was applied. The effect of free carrier absorption decreases with increase of composition of PdO.
We demonstrated lattice parameters of vanadium dioxide (VO2) films grown on Al2O3 (001) single crystals across metal-insulator transition through temperature-controlled X-ray diffraction measurements. Changes of lattice length for both monoclinic and tetragonal phases were analyzed against temperature. Films prepared by reactive sputtering method were examined to discuss the dependence of transition property on lattice parameters. We revealed correlation between transition temperature and c-axis length of tetragonal phase.
We studied the electrical properties of (BixTey+Sb) alloyed thin films and (BixTey+Cd) alloyed thin films. They were prepared on a SiO2 glass substrate by electron beam evaporation and radio-frequency spattering method. The values of voltage sensitivity were 0.71 [mV], 43.91 [mV], and 78 [mV/W] for 0.5-μm-thick Bi2Te2.4, 0.5-μm-thick Bi2Cd2.6Te5.5, and 0.1-μm-thick Bi2Sb1.9Te4.9, respectively, and the minimum value of noise equivalent power was 6.46×10-5 [W/Hz1/2] for 0.1-μm-thick Bi2Sb1.9Te4.9 at a biased current of 10 [mA], and a blackbody furnace temperature was 1000 [°C]. The maximum value of power factor was 1.15×10-3 W/mK2 at 450 K for Bi2Te2.4, 2.46×10-4 W/mK2 at 550 K for Bi2Te3.6+InSb6, and 8.90×10-6 W/mK2 at 550 K for InSb2.2.
We fabricated an organic thin film prepared by oligomers organic material according to the solution method and examined the quality of thin film by X-Ray diffractometer. Based on the results, we fabricated flexible-organic field effect transistors by spin-coating method. We adopted a polyethylenenaphthalate (PEN) film as the substrate, a cross-linked poly-4-vinylphenol (PVP) thin film as the gate dielectric insulation layer and a soluble quaterthiophene layer as an active layer. The carrier mobility of the prepared organic-field effect transistor, the threshold voltage and the ON/OFF ratio are 2.27×10-3 cm2/Vs, -37 V and 3×102 respectively.
A film formed by electro-deposition in methanol was successfully grown on single tungsten field emission tip. Carbon clusters containing hydrogen were detected from the coated tip by femto-second laser atom-probe. It was found that electrons which were needed to capture one carbon atom into the film were an order of 5. Emission current vs. voltage characteristic from the protrusion at the apex of the covered tip obeyed Fowler-Nordheim relationship, and gave work function about 4.1 eV. Good short-term stability in emission current was observed.