Ge nitride formation in N-doped amorphous Ge2Sb2Te5

Abstract

The chemical state of N in N-doped amorphous Ge2Sb2Te5 (a-GST) samples with 0–14.3Nat.% doping concentrations was investigated by high-resolution x-ray photoelectron spectroscopy (HRXPS) and Ge K-edge x-ray absorption spectroscopy (XAS). HRXPS showed negligible change in the Te 4d and Sb 4d core-level spectra. In the Ge 3d core-level spectra, a Ge nitride (GeNx) peak developed at the binding energy of 30.2eV and increased in intensity as the N-doping concentration increased. Generation of GeNx was confirmed by the Ge K-edge absorption spectra. These results indicate that the N atoms bonded with the Ge atoms to form GeNx, rather than bonding with the Te or Sb atoms. It has been suggested that the formation of Ge nitride results in increased resistance and phase-change temperature.

Chemical states of Bi-doped GeTe (Bi: 6 at.%) thin film in structural phase transition investigated by synchrotron X-ray photoelectron spectroscopy

“…After sputtering, however, the Ge 3d was represented by a single chemical state in the amorphous phase. The analysis confirmed that Ge oxide was mainly formed on the top surface by the exposure to air, and that the single chemical state of clean a-GBT was obtained by low-energy Ne þ ion sputtering [11,12]. In the 'A' spectrum of the valence spectra (d), humps (w6, w9, w13 eV) attributable to oxide were observed.…”

“…To remove any surface oxide and to produce clean amorphous GBT film [13], the GBT was Ne þ ion sputtered with an ion beam energy of 0.6 kV for 1 h [13]. (A 20 nm-thick oxide impurity layer grows when the GeeSbeTe system is exposed to air [11,12]). The clean amorphous GBT was then annealed under UHV to obtain the meta-stable crystalline phase.…”

“…Clean amorphous GBT free of surface oxygen impurities was obtained by Ne þ ion sputtering with low ion beam energy, and the meta-stable crystalline phase was obtained by in-situ annealing of the clean GBT under ultrahigh vacuum (UHV) [11,12]. Subsequently, the differences between those chemical states were investigated.…”

Effect of indium on phase-change characteristics and local chemical states of In–Ge–Sb–Te alloys

“…J. Shin, 1,a͒ Youn-Seon Kang, 2 Anass Benayad, 3 Ki-Hong Kim, 3 Y. M. Lee,1 M.-C. Jung, 1 Tae-Yon Lee, 2 Dong-Seok Suh, 2 Kijoon H. P. Kim We introduce single-phase In-Ge-Sb-Te ͑IGST͒ quaternary thin film ͑fcc structure when crystallized͒ deposited by cosputtering from Ge 2 Sb 2 Te 5 ͑GST͒ and In 3 Sb 1 Te 2 targets. This film, compared with the GST ternary system, provides a significant increase of amorphous-to-crystalline transformation temperature.…”

Ion Implantation in Phase Change Ge2Sb2Te5 Thin Films for Non Volatile Memory Applications

“…Both experimental data , Jung et al, 2007 and atomic ab initio calculations (Cho et al, 2011) performed on nitrogen doped GST have shown that the N atoms are prevalently bonded with the Ge atoms to form GeN x , rather than bonding with the Te or Sb atoms. Moreover, data of Ref.…”