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Article Dans Une Revue Physical Review B: Condensed Matter and Materials Physics (1998-2015) Année : 2008

Interplay between morphology and metallization in amorphous-amorphous transitions

Résumé

We present spectacular evidence of metallization of amorphous Ge films under high pressure using optical micrographs and Raman-scattering and x-ray-absorption spectroscopies. This transformation is identified as a low-density amorphous LDA to high-density amorphous HDA transition, relevant to a large class of systems including amorphous ice, semiconductors, and oxides. We have discovered that this transition initiates at the surface of the LDA sample, characterized intrinsically by a thickness dependent density of voids. Contrary to the case of transitions involving stable crystalline solid phases, our observations show that pressure-induced phase transitions in inhomogeneous amorphous samples are morphology driven and are favored for lower defect void densities. The metal disordered phase is observed first at 8 GPa for a lower density of voids, transforming to a metastable ordered phase upon depressurization. The local HDA structure is characterized by an increase in the first-neighbor coordination number, average distance, and variance
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Dates et versions

hal-00338490 , version 1 (13-11-2008)

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A. Di Cicco, A. Congeduti, F. Coppari, J. C. Chervin, F. Baudelet, et al.. Interplay between morphology and metallization in amorphous-amorphous transitions. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2008, 78, pp.033309. ⟨10.1103/PhysRevB.78.033309⟩. ⟨hal-00338490⟩
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