Takuya Kunihiro

High precision isotope micro-imaging of materials

Abstract Secondary ion mass spectrometry (SIMS) is widely used to identify the isotope ratio of the micro-area of materials. We demonstrate that the precision and spatial resolution of an ion microscope using SIMS coupled with a newly developed solid-state ion imager can be extended to two-dimensional isotope ratio imaging with permil-precision. An isotopic map for oxygen clearly reveals the distribution of 4% enrichment of 16 O in spinel particles embedded in melilite from a Ca–Al-rich inclusion of a carbonaceous chondrite. This characterization technique called isotopography thus provides the eyes to see small heterogeneity of isotope abundance in micro-scale. It is likely to find broad application in earth, material, and life science research.

A low dark current stacked CMOS-APS for charged particle imaging

A stacked CMOS-active pixel sensor (APS) with a newly devised pixel structure for charged particle detection has been developed. A twin well pixel with a p-MOS readout transistor achieves low leakage current caused by a hot carrier effect at low temperature as low as 5/spl times/10/sup -8/ V/s at the pixel electrode. The total read noise floor of 0.1mVrms was obtained by non-destructive readout CDS with the CDS interval of 21 seconds.