Hexagonal germanium formed via a pressure-induced phase transformation of amorphous germanium under controlled nanoindentation

James S. Williams*, Bianca Haber, Sarita Deshmukh, Brett C. Johnson, Brad D. Malone, Marvin L. Cohen, Jodie E. Bradby

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    17 Citations (Scopus)

    Abstract

    We have studied the stable end phase formed in amorphous germanium (a-Ge) films that have been subjected to a pressure-induced phase transformation under indentation loading using a large (20 μm) spherical indenter. After indentation the samples have been annealed at room temperature to remove any residual unstable R8 and BC8 phases. Raman spectroscopy indicates a single broad peak centred around 292 cm-1 and we have used first principles density functional perturbation theory calculations and simulated Raman spectra for nano-crystalline diamond cubic germanium (DC-Ge) to help identification of the final phase as hexagonal diamond germanium (HEX-Ge). Transmission electron microscopy and selected area diffraction analysis confirmed the presence of a dominant HEX-Ge end phase. These results help explain significant inconsistencies in the literature relating to indentation-induced phase transitions in DC- and a-Ge.

    Original languageEnglish
    Pages (from-to)355-359
    Number of pages5
    JournalPhysica Status Solidi - Rapid Research Letters
    Volume7
    Issue number5
    DOIs
    Publication statusPublished - May 2013

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