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In this paper heavy negative-ion sources which we developed and their applications for materials science are reviewed. Heavy negative ions can be effectively produced by the ejection of a sputtered atom through the optimally cesiated surface of target with a low work function. Then, enough continuous negative-ion currents for materials-science applications can be obtained. We developed several kinds of sputter-type heavy negative-ion sources such as neutral- and ionized-alkaline metal bombardment-type heavy negative-ion source and rf-plasma sputter type. In the case where a negative ion is irradiated on a material surface, surface charging seldom takes place because incoming negative charge of the negative ion is well balanced with outgoing negative charge of the released secondary electron. In the negative-ion implantation into an insulator or insulated conductive material, high precision implantation processing with charge-up free properties can be achieved. Negative-ion implantation technique, therefore, can be applied to the following novel material processing systems: the surface modification of micrometer-sized powders, the nanoparticle formation in an insulator for the quantum devices, and the nerve cell growth manipulation by precise control of the biocompatibility of polymer surface. When a negative ion with low kinetic energy approaches the solid surface, the kinetic energy causes the interatomic bonding (kinetic bonding), and formation of a metastable material is promoted. Carbon films with high constituent of sp3 bonding, therefore, can be formed by carbon negative-ion beam deposition. [ABSTRACT FROM AUTHOR]

Deals with the application of a compact microwave ion source to the low temperature growth of transition metal nitride thin films for the cathode of vacuum microeletronics devices. Ion beam assisted deposition of transition metal nitrides; Film property; Electron binding energy; Endurance against low energy ion bombardment.

The energy distribution of the ion beam extracted from the compact microwave ion source for extremely low voltage ion extraction was measured with Ar and CO as a discharge gas. The energy distribution was measured by the retarding field method, and changes with respect to the change in gas pressure were observed. The obtained data were arranged by the peak energy and the energy spread. For both gases, the peak energy and the energy spread decreased with an increase in the gas pressure. The energy spread of approximately 5 eV with the peak energy of 15 eV were obtained for Ar gas at the pressure of 10[sup -2] Pa. For CO gas, the peak energy was higher than Ar and approximately 20 eV. The energy spread was 6 eV at the pressure of 10[sup -2] Pa. These values agreed with the peak energy and energy spread that were estimated previously from the mass spectra analysis. Since the ion source was designed to be used in the researches of low energy ion-solid interaction, these characteristics satisfy the requirements for this purpose. [ABSTRACT FROM AUTHOR]

Focuses on measurement of performance of a compact microwave ion source developed for extremely low energy ion extraction. Characteristics of ion source; Current-voltage characteristics; Estimation of ion energy; Estimation of energy spread.

Proposes a criterion for decrease of electric field at the ionization point of liquid-metal ion sources. Dependence of electric field on source current based on postionization theory; Space-charged limited current with small charge approximation; Dependence of emission current and current density on electric field.

Deals with the performance of a molecular ion implanter equipped with a liquid-metal alloy ion source. Configuration of ion implanter; Evaluation of optics; Separation of molecules; Molecular ion implantation.

Develops a compact microwave ion source for low-energy application. Influence of plasma density on the extraction of ions; Presence of a plasma expansion cup in the ion source; Measurement of the current-voltage characteristics of the ion source.

A new type of impregnated-electrode-type liquid-metal ion source, which eliminated the heating problem in the previous source, has been developed with multiple tip and reservoirs (TAR's). In the present ion source, the TAR's are connected electrically in series by modifying the TAR holding system. In order to achieve uniform heating of the TAR's, the materials of the knife-edged electrodes, which introduce the heating current to the TAR's, were examined. Tantalum electrodes exhibited better results as compared with the conventional Mo electrodes. Both of the two TAR's could be heated up to 700 °C with a heating power of 200 W. The maximum indium ion current of 9.1 mA was obtained from the four-TAR source with 40 emission points. Since the present ion current was limited by the current capacity of the extraction power supply, an ion current of more than 10 mA will be expected with a larger power supply. The results indicated that an ion current approximately proportional to the number of the emission points was obtained. This kind of ion source could be used as a general ion source in materials science. [ABSTRACT FROM AUTHOR]