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Articles you may be interested inSecondary ion mass spectrometry characterization of source/drain junctions for strained silicon channel metal-oxide-semiconductor field-effect transistors

We examined the infrared spectrum of Si(111) after terminating its surface with silicon monohydride and immersing it in various concentrations of HF solution to induce fluorine adsorption. After immersion in HF solution, a part of the silicon monohydride surface was etched and (100), (010) and (001) steps composed of strained dihydrides appeared. The silicon-hydrogen stretching frequency for the monohydride was shifted by the fluorine adsorption. Angle-resolved X-ray photoelectron spectroscopy revealed that fluorine penetrates the silicon lattice as well as exists close to the surface. We conclude that fluorine does not terminate the surface silicon dangling bond but inhabits interstitial sites just below the silicon surface.

Aqueous HF etching of the silicon surface removes surface oxide, leaving a silicon surface terminated inhomogeneously by silicon mono-, di-, and trihydrides. We studied the effect of the immersion in water following the HF etching, on the surface hydride structure on Si(111), by measuring Si-H stretching vibration using infrared absorption spectroscopy. Immersion in boiling water (100°C) for 600 s produces a surface homogeneously terminated with silicon monohydride normal to the surface and free of oxidation. We concluded that water can remove silicon dihydride and trihydride and leave a silicon surface terminated with monohydride. The homogeneous surface has a low defect density of less than 0.5%.

A 100‐nm‐thick lithium iron phosphate (LiFePO4) film was deposited by sputtering, and charge–discharge cycle tests were performed using LiFePO4 films as cathodes in electrochemical cells. After removing the electrolyte, the charged and discharged LiFePO4 thin film cathodes were investigated using XPS. XPS results revealed that the peak area intensity of Fe2+ state increases for charged cathodes, while that of Fe3+ increases for discharged cathodes. In addition, the variation of Fe3+ and Fe2+ peak area intensities gradually attenuated as the number of charge–discharged cycles increased. The results reflect the performance of the battery and its degradation. Copyright © 2014 John Wiley & Sons, Ltd.