Search

We have investigated the core levels and the valence band of (Ge2Sb2Te5)1-x(In3Sb1Te2)x quaternary phase system (IGST) by means of x-ray photoelectron spectroscopy. A systematic shift of Sb 3d and Ge 2p core-level peaks toward lower binding energies side was observed with increasing indium amount, whereas the In 3d and Te 3d core peaks showed less change. The Sb 3d and Ge 2p core-level shift is attributed to an increase in the electronic charge of p-electrons dependent of indium amount. The valence band spectra show a distinct change in the sp configuration with indium concentration change. The change in the local bonding as the indium amount increase has a profound impact on both local atomic arrangement and amorphous-to-crystalline transformation temperature. The difference in the photoemission spectra have been discussed according to a simple structural model suggesting that the Na site in IGST can be occupied by Te, Sb, In, and vacancy, whereas in GST it is occupied only by Te. [ABSTRACT FROM AUTHOR]

The present paper reports the energy loss near-edge structure (ELNES) study of monoclinic HfO2 (m-HfO2) and tantalum doped m-HfO2 (Ta0.1Hf0.9O2) thin films prepared by radio frequency magnetron co-sputtering method. A change in the O K-ELNES spectra was observed as the amount of dopant increases. In order to precise the common features and the differences as a function of Ta defect nature (substitutional or interstitial) in HfO2, the O K-ELNES were commented with respect to density functional theory calculations implemented in Vienna ab initio simulation package code. The calculated Ta doped HfO2 band structure showed that substitutional tantalum is the dominant defect and the spectral differences between doped and non-doped HfO2 are mainly originated from the change in the local cation distribution around the oxygen atoms. [ABSTRACT FROM AUTHOR]