We have grown Ce- and Na-co-doped LiCaAlF6 (Ce,Na:LiCAF) single crystals with various Ce and Na concentrations by the micro-pulling-down (μ-PD) method. Physical properties such as crystallinity, transmittance, photoluminescence, scintillation, and radiation resistance were investigated to evaluate the effects of charge compensation by Na co-doping in the Ce-doped LiCaAlF6 (Ce:LiCAF) crystal. Ce2%:LiCAF, Ce1%Na1%:LiCAF, Ce1.5%Na1.5%:LiCAF, and Ce2%Na2%:LiCAF crystals with no visible cracks and inclusions were prepared. The Ce1%Na1%:LiCAF crystal showed high crystallinity comparable to the crystal grown by the Czochralski method. In the transmittance and photoluminescence spectra of all crystals, an absorption peak around 270 nm and emission peaks around 285 and 310 nm originating from Ce3+ ions were observed, respectively. With increasing Ce and Na concentrations, the light yield systematically increased, and scintillation decay times decreased. Improvement of radiation resistance accomplished by charge compensation due to Na co-doping is clearly demonstrated.

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Raman spectroscopy has been used to characterize the formation of Pt-silicide on the Si(100) and (111) surfaces. 5–200 Å Pt overlayers were deposited on atomically clean Si surfaces, reacted and studied by photoemission, Auger spectroscopy and transmission electron microscopy (TEM). The Raman spectra were obtained with a multichannel Raman system; this allowed direct measurements of very thin overlayers on crystalline surfaces. For interfaces reacted at T>300 °C, the Raman spectra showed new lines; the strongest at 82 and 140 cm−1. These are assigned to PtSi by correlation with the TEM phase identification. The relative intensities of the PtSi Raman lines depend on the Pt thickness and the Si substrate orientation. For T<200 °C, these features are broadened and weaker, suggesting a limited (incomplete) reaction. This is consistent with the electron spectroscopy and TEM measurements on these samples. Our measurements show Raman spectroscopy can be used for silicide interface studies to identify and characterize (without extra sample preparation) thin reacted layers, even at the buried interface between unreacted metal and crystalline Si.

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