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Structural Analyses of Phase Stability in Amorphous and Partially Crystallized Ge-Rich GeTe Films Prepared by Atomic Layer Deposition
- Source :
- ACS applied materialsinterfaces. 9(47)
- Publication Year :
- 2017
-
Abstract
- The local bonding structures of GexTe1-x (x = 0.5, 0.6, and 0.7) films prepared through atomic layer deposition (ALD) with Ge(N(Si(CH3)3)2)2 and ((CH3)3Si)2Te precursors were investigated using Ge K-edge X-ray absorption spectroscopy (XAS). The results of the X-ray absorption fine structure analyses show that for all of the compositions, the as-grown films were amorphous with a tetrahedral Ge coordination of a mixture of Ge-Te and Ge-Ge bonds but without any signature of Ge-GeTe decomposition. The compositional evolution in the valence band electronic structures probed through X-ray photoelectron spectroscopy suggests a substantial chemical influence of additional Ge on the nonstoichiometric GeTe. This implies that the ALD process can stabilize Ge-abundant bonding networks like -Te-Ge-Ge-Te- in amorphous GeTe. Meanwhile, the XAS results on the Ge-rich films that had undergone post-deposition annealing at 350 °C show that the parts of the crystalline Ge-rich GeTe became separated into Ge crystallites and rhombohedral GeTe in accordance with the bulk phase diagram, whereas the disordered GeTe domains still remained, consistent with the observations of transmission electron microscopy and Raman spectroscopy. Therefore, amorphousness in GeTe may be essential for the nonsegregated Ge-rich phases and the low growth temperature of the ALD enables the achievement of the structurally metastable phases.
- Subjects :
- 010302 applied physics
X-ray absorption spectroscopy
Materials science
Absorption spectroscopy
02 engineering and technology
021001 nanoscience & nanotechnology
01 natural sciences
Amorphous solid
Crystallography
Atomic layer deposition
symbols.namesake
X-ray photoelectron spectroscopy
0103 physical sciences
symbols
General Materials Science
Crystallite
0210 nano-technology
Raman spectroscopy
Phase diagram
Subjects
Details
- ISSN :
- 19448252
- Volume :
- 9
- Issue :
- 47
- Database :
- OpenAIRE
- Journal :
- ACS applied materialsinterfaces
- Accession number :
- edsair.doi.dedup.....bd78fac86b0aaa01b636dd41d54337f5