We developed a variable-temperature scanning microwave microscope (VT-SμM) that can perform high-throughput materials characterization in the temperature range between 4K and room temperature. As a sensor probe we used a high-Q coaxial cavity resonator, which was mounted on the low-temperature stage to allow variable-temperature measurements. We carried out systematic studies on the thermal degradation of the conducting polymers using the combinatorial libraries of polyaniline and polythiophene thin films, which showed rapid decrease of conductivity above 300C and 250C, respectively. The low-temperature performance of the VT-SμM was demonstrated by the measurement of composition-spread Nd1-xSrxMnO3 thin film, for which we succeeded in detecting the clear metal-insulator transition at 100K. We also propose a simple and easy method for the quantitative analysis of conductive thin films, by using the standard composition-spread thin films of Ti1-xNbxO2.

We have demonstrated position controlled GaN nano structures with a combination of surface treatments and nucleation sites control assisted by low energy focused ion beam. Ga ions in the range of 100 eV - 10 keV were irradiated onto the surface of the As-terminated Si (100) to create the nucleation sites. The deposited Ga atoms migrated on the surface and were trapped at the nucleation sites to form Ga droplets. Subsequently an excited atomic nitrogen source was supplied to the surface. By SEM observation, the GaN microcrystals of diameter about 800 nm were found to be allocated every 2 μm periodically on the substrates, and cathodoluminescence peaks from GaN nano structures were observed.

We developed a scanning microwave microscope (SμM) designed for characterizing local electric properties at low temperatures. A high-Q λ/4coaxial cavity was used as a sensor probe, which can detect the change of quality factor due to the tip-sample interaction with enough accuracy. From the measurements of combinatorial samples, it was demonstrated that this SμM system has enough performance for high-throughput characterization of sample conductance under variable temperature conditions.

In this paper, we demonstrate the use of thermal probe method that is capable of mapping Seebeck coefficient, thermal conductivity and contact resistance on a micrometer scale. We show the successful screening example on pseudo binary (Bi1−xSbx)2Te3 (0.5<x<1) bulk composition-spread sample prepared by conventional powder metallurgy process. Another demonstration is a novel attempt to combine the combinatorial PLD and the thermal probe method. A pseudo ternary diagram of nickel-copper-manganese oxides fabricated on Nb doped STO substrate was used for the screening. The mapping of electrical resistance over the ternary diagram yields a lot of information, which is essential for materials researches on complex, multi-composition systems.

This paper demonstrates a new technique to form a patterned metal-oxide film on a silicon wafer using a local electric field. The idea of the technique involves using an interaction between metal-organic molecules dissolved in a non-polar solvent and a local electric potential field on a substrate. In this paper, an alkoxide and a metal-organic complex were used as metalorganic precursors. The precursor molecules were selectively deposited at the electrified region of the substrate. The deposited precursor films were heated with an electric furnace to form oxide films. Patterned TiOx and Sr-Ti oxide films were formed on a SiOx/Si substrate. These patterned thin films are potentially applicable to electric and optical devices. We believe that this new technique provides a new bottom-up process of molecular assembly for nanofabrication.

A systematical growth temperature and oxygen ambient dependency of SrTiO3/Si interface structures were investigated using a growth temperature gradient pulse laser deposition (PLD) system and cross sectional high resolution transmission electron microscopy (HRTEM). A SiO2 interfacial layer and an amorphized SrTiO3 layer were observed at the interface for the thin films grown on Si (100) at growth temperatures above 600°C. Our results show that at growth temperatures higher than 600°C, the formation of the amorphized SrTiO3 layer is strongly growth temperature and also oxygen partial pressure dependent.

A scanning microwave microscope (Sm M) for high-throughput characterization of combinatorial dielectric materials has been developed using a lumped constant resonator probe. The probe consists of a microwave oscillator module equipped with a thin conducting needle and an outer conductor ring, which detects the dielectric constant of the sample just beneath the needle as a frequency shift of the resonator. The quantitative analysis of the dielectric constant for the bulk and the thin-film samples was carried out based on the measurement of gap-length dependence of the frequency shift. The analysis method was successfully applied to the characterization of composition-spread BaxSr1-xTiO3 thin film sample. The evaluation of far-field contribution to the frequency shift was found to be crucial for the accurate determination of dielectric constant especially in the characterization of combinatorial thin films.

We have investigated a resist-trimming process for SAL601 chemically amplified negative electron beam resist. Ultra-fine SAL601 resist patterns with a width of 16nm were obtained by an isotropic trimming process in oxygen plasma. This pattern resolution in SAL601 could not be obtained through direct electron beam lithography alone. Using the trimmed electron beam resists, we have successfully fabricated ultra-fine poly-silicon patterns of less than 20nm width. We applied this nanolithography technique to fabricating an ultra-small metal-oxide-semiconductor field-effect-transistor (MOSFET) and revealed that this trimming process is a useful method for nanometer-scale silicon device fabrication.