Novel heterostructured Ge nanowires based on polytype transformation

Laetitia Vincent (1) , Gilles Patriarche (2) , Géraldine Hallais (1) , Charles Renard (1) , Cyrille Gardès (1) , David Troadec (3) , Daniel Bouchier (1)

1 IEF - Institut d'électronique fondamentale
2 LPN - Laboratoire de photonique et de nanostructures
3 IEMN - Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520

We report on a strain-induced phase transformation in Ge nanowires under external shear stresses. The resulted polytype heterostructure may have great potential for photonics and thermoelectric applications. ⟨111⟩-oriented Ge nanowires with standard diamond structure (3C) undergo a phase transformation toward the hexagonal diamond phase referred as the 2H-allotrope. The phase transformation occurs heterogeneously on shear bands along the length of the nanowire. The structure meets the common phenomenological criteria of a martensitic phase transformation. This point is discussed to initiate an on going debate on the transformation mechanisms. The process results in unprecedented quasiperiodic heterostructures 3C/2H along the Ge nanowire. The thermal stability of those 2H domains is also studied under annealing up to 650°C by in situ TEM.

Mots clés: nanowires; phase-transformation; shear-stress; allotrope; heterostructure

Domaines: Physique [physics]

Laetitia Vincent, Gilles Patriarche, Géraldine Hallais, Charles Renard, Cyrille Gardès, et al.. Novel heterostructured Ge nanowires based on polytype transformation. Nano Letters, 2014, 14, pp.4828-4836. ⟨10.1021/nl502049a⟩. ⟨hal-01058064⟩