Hifumi Tamura

Tracer diffusion coefficient of oxide ions in LaCoO3 single crystal

Abstract The tracer diffusion coefficient, D∗ O , of oxide ions in LaCoO3 single crystal was determined over the temperature range of 700–1000°C by a gas-solid isotopic exchange technique using 18O tracer. For the determination, two methods, the gas phase analysis and the depth profile measurement, were employed. Under an oxygen pressure of 34 Torr, the temperature dependence of D∗ O in LaCoO3 was expressed by D∗ O ( cm 2 · sec −1 ) = 3.63 × 10 4 exp − (74 ± 5) kcal · mole −1 RT D∗ O at 950°C was found to be proportional to P−0.35O2. The diffusion of oxide ions occurs through a vacancy mechanism. The activation energy for the migration of oxide ion vacancies was estimated as 18 kcal · mole−1.

Electrical Properties of Focused-Ion-Beam Boron-Implanted Silicon

Electrical properties of 16 keV, focused-ion-beam (FIB) (beam diameter: 1 µm, current density: 50 mA/cm2) boron-implanted silicon layers have been investigated as a function of beam scan speed and ion dose, and compared with those obtained by conventional implantation (current density: 0.4 µA/cm2). High electrical activation of the FIB implanted layers is obtained by annealing below 800°C as a result of the increase in amorphous zones created in the implanted layers. Amorphous zone overlapping is assumed to occur at FIB implantation doses of 3–4×1015 ions/cm2 from the results of electrical activation and the carrier profile of implanted regions annealed at low temperature, if beam scan speed is lowered to about 10-2 cm/s.

Condensation of bombarding gallium ions on a silicon surface

Direct observation of bombarding 5–15‐keV Ga+ ion condensation on a Si target is achieved using a scanning ion microscope with a liquid‐Ga ion source. The liquidlike pieces of condensed Ga move about easily to join or split. Condensation takes place beyond a critical ion dose, which is roughly explained by an implanted‐ion build‐up model.

Short‐channel MOS FET’s fabricated by self‐aligned ion implantation and laser annealing

Short‐channel MOS FET’s are successfully fabricated using Q‐switched ruby laser irradiation on As‐implanted sources and drains. Implantation and laser irradiation are both self‐aligned by the polysilicon gate electrodes. The threshold‐voltage–vs–channel‐length relation is improved as a result of the extremely limited lateral diffusion of implanted As atoms.

Laser‐annealing behavior of a phosphorus‐implanted silicon substrate covered with a SiO2 film

Laser‐annealing behavior of phosphorus‐implanted silicon substrates is investigated as a function of the SiO2 film thickness formed on implanted surfaces. Surface‐carrier concentration after laser irradiation through the SiO2 layers shows periodic enhancement in relation to SiO2 thickness. Calculation of laser energy transferred into the silicon surface through various SiO2 film thicknesses is carried out and the results agree well with the experiments.

Correction of secondary ion intensity by a new total ion monitoring method

A new total ion monitoring (TIM) method is developed for the correction of secondary ion intensity changes. These changes depend on the primary ion beam current fluctuations, surface topography, and surface state of the specimens to be analyzed. The total ions detection sensitivity of this new TIM is 103 times better than that of the conventional method using the absorbed primary current. It is possible to obtain the true concentration image of a specific element for the specimen surface by dividing the specific ions (mass analyzed) by the total emitted ions (without mass analysis) at a certain solid angle. This process eliminates the influence of primary ion beam current fluctuations, surface topography, and surface state. In this paper, the new TIM method is described. In addition, its applications to low alloy steel fracture surfaces, a color television shadow mask, and Quenched and Tempered steel fracture surfaces are investigated. The obtained results indicate good agreement with the true concentration.

Carbon Needle Emitter for Boron and Aluminum Ion Liquid-Metal-Ion Sources

A long-life glassy carbon needle emitter for a boron liquid-metal-ion source utilizing NiB alloy is developed. A lifetime (i.e. 50–90 hours) is achieved. The nickel coated carbon emitter is found also to be useful with an aluminum liquid-ion source.

An electrohydrodynamic iom source with a reservoir and an emitter tip heated by electron bombardment

Abstract An electrohydrodynamic (EHD) ion source equipped with a reservoir and an emitter tip heated by electron bombardment was constructed. Owing to the heating method and reservoir, this source can produce various ion species including high melting point materials stably for a long time. Operated with metals such as indium and gold, an intense and stable ion beam was obtained from each material. This ion source can also be operated as a surface ionization source which produce ions at a very small area of the emitter tip heated by electron bombardment.

Stable Field Emission of Electrons from Liquid Metal

Experiments were carried out on the field emission of electrons from Ga-In-Sn liquid alloy and a stable DC emission was observed in addition to the pulse explosion already reported. The emission stability depended on the apex radius of the tungsten tip to which the liquid metal adhered to form a cone. When we used an emitter with an apex radius smaller than 0.5 µm, Fowler-Nordheim plots in the DC mode were heavily influenced by the adhesive state at its surface.

Development of Phosphorus Liquid-Metal-Ion Source

A phosphorus liquid-metal-ion source that uses a Cu–P alloy as its source material is described. The P+ ion emission current is about 10% of total emission current, which consists mainly of Cu+ ions. Energy spread of P+ ions is 25 eV at a total current of 30 µA, while that of Cu+ is 28 eV. A source lifetime of more than 20 hours is achieved at a total current of 50–60 µA.