Activation Energy of Metastable Amorphous Ge2Sb2Te5 from Room Temperature to Melt
| Autor: | Helena Silva, Gokhan Bakan, Ali Gokirmak, Kadir Cil, Adam Cywar, Sadid Muneer, Faruk Dirisaglik, Lhacene Adnane, Jake Scoggin, Chung H. Lam |
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| Rok vydání: | 2018 |
| Předmět: |
010302 applied physics
Condensed Matter - Materials Science Materials science Condensed matter physics Scale of temperature Fermi level General Physics and Astronomy Materials Science (cond-mat.mtrl-sci) FOS: Physical sciences 02 engineering and technology Activation energy 021001 nanoscience & nanotechnology 01 natural sciences Temperature measurement lcsh:QC1-999 Amorphous solid symbols.namesake Electrical resistivity and conductivity Metastability 0103 physical sciences symbols 0210 nano-technology Supercooling lcsh:Physics |
| Zdroj: | AIP Advances, Vol 8, Iss 6, Pp 065314-065314-8 (2018) |
| DOI: | 10.48550/arxiv.1805.04054 |
| Popis: | Resistivity of metastable amorphous Ge2Sb2Te5 (GST) measured at device level show an exponential decline with temperature matching with the steady-state thin-film resistivity measured at 858 K (melting temperature). This suggests that the free carrier activation mechanisms form a continuum in a large temperature scale (300 K - 858 K) and the metastable amorphous phase can be treated as a super-cooled liquid. The effective activation energy calculated using the resistivity versus temperature data follow a parabolic behavior, with a room temperature value of 333 meV, peaking to ~377 meV at ~465 K and reaching zero at ~930 K, using a reference activation energy of 111 meV (3kBT/2) at melt. Amorphous GST is expected to behave as a p-type semiconductor at Tmelt ~ 858 K and transitions from the semiconducting-liquid phase to the metallic-liquid phase at ~ 930 K at equilibrium. The simultaneous Seebeck (S) and resistivity versus temperature measurements of amorphous-fcc mixed-phase GST thin-films show linear S-T trends that meet S = 0 at 0 K, consistent with degenerate semiconductors, and the dS/dT and room temperature activation energy show a linear correlation. The single-crystal fcc is calculated to have dS/dT = 0.153 {\mu}V/K for an activation energy of zero and a Fermi level 0.16 eV below the valance band edge. Comment: 5 pages, 5 figures |
| Databáze: | OpenAIRE |
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