Abstract
Although it has been confirmed by diamond anvil cell experiments that germanium transforms under hydrostatic pressure from the normal diamond cubic phase (Ge-I) to the metallic β-tin phase (Ge-II) and re-transforms to Ge-III (ST12 structure) or Ge-IV (BC8 structure) during release of the pressure, there are still controversies about whether the same transformations occur during nanoindentation. Here, we present new evidence of indentation-induced phase transformations in germanium. Nanoindentation experiments were performed on a (100) Ge single crystal using two triangular pyramidal indenters with different tip angles - the common Berkovich and the sharper cube-corner. Although the indentation load-displacement curves do not show any of the characteristics of phase transformation that are well-known for silicon, micro-Raman spectroscopy in conjunction with scanning electron microscopy reveals that phase transformations to amorphous and metastable crystalline phases do indeed occur. However, the transformations are observed reproducibly only for the cube-corner indenter.
Original language | English |
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Article number | T6.9/R10.9 |
Pages (from-to) | 277-282 |
Number of pages | 6 |
Journal | Materials Research Society Symposium Proceedings |
Volume | 843 |
State | Published - 2005 |
Event | Surface Engineering 2004 - Fundamentals and Applications - Boston, MA, United States Duration: Nov 30 2004 → Dec 2 2004 |