Jinmo Kim

Time-of-flight secondary ion mass spectrometry chemical imaging analysis of micropatterns of streptavidin and cells without labeling

A bismuth cluster ion-beam-based time-of-flight secondary ion mass spectrometry (TOF-SIMS) has been successfully used to image micropatterns of streptavidin and Chinese hamster ovary (CHO-k1) cells, as received and without any labeling. Three different analysis ion beams (Bi+, Bi3+, and Bi32+) were compared to obtain label-free TOF-SIMS chemical images of micropatterns of streptavidin, which were subsequently used for generating biotinylated cell patterns. Unlike using a Bi+ ion beam, using a Bi3+ or Bi32+ primary analysis ion beam yielded well-contrasted-TOF-SIMS images of streptavidin characteristic secondary ions. A principal component analysis of TOF-SIMS data was performed to generate a chemical image of the streptavidin itself. A chemical specific TOF-SIMS image analysis gave us a better understanding of the localization of cells at the outer boundaries of the streptavidin-patterned circles. Our work suggests that using cluster-ion analysis beams together with multivariate data analysis for TOF-SIMS...

Electrical Characteristics of Al/CeO2(200)/Si(100) and Al/CeO2(111)/Si(100) Metal-Insulator-Semiconductor Structure.

Capacitance–voltage (C–V) and current–voltage (I–V) characteristics of Al/CeO2/Si(100) metal-insulator-semiconductor structures were found to be dependent on the crystal orientations of CeO2 thin films, which were deposited by radio-frequency magnetron sputtering. The C–V curve for the Al/CeO2/Si(100) structure made with CeO2 with (200)-preferred orientation (referred to as CeO2(200)) did not show any notable hysteresis, while the Al/CeO2/Si(100) structure made with CeO2 with (111)-preferred orientation (referred to as CeO2(111)) showed a counter-clockwise hysteresis, whose width was as high as ~1.5 V. The hysteresis difference between Al/CeO2(200)/Si(100) and Al/CeO2(111)/Si(100) is thought due to the difference in the preferred orientation of the CeO2 layer, and thus the stress between the CeO2 thin film and the Si substrate. The Al/CeO2(111)/Si(100) structure with CeO2 of larger grains showed larger leakage current than the Al/CeO2(200)/Si(100) structure with CeO2 of smaller grains.