Unraveling the strain state of GaN down to single nanowires

Thomas Auzelle (1) , Xavier Biquard (2) , Edith Bellet-Amalric (1) , Zhihua Fang (1) , Herve Roussel (3) , Ana Cros (4) , Bruno Daudin (1)

1 NPSC - Nanophysique et Semiconducteurs
2 NRS - Nanostructures et Rayonnement Synchrotron
3 LMGP - Laboratoire des matériaux et du génie physique
4 Univ Valencia, Inst Ciencia Mat, E-46980 Paterna, Valencia, Spain

GaN nanowires (NWs) grown by molecular beam epitaxy are usually assumed free of strain in spite of different individual luminescence signatures. To ascertain this usual assumption, the c/a of a GaN NW assembly has been characterized using both X-ray diffraction and Raman spectroscopy, with scaling the measurement down to the single NW. Free-standing single NWs have been observed free of strain-defined as [c/a = (c/a)(o)]/(c/a)(o)-within the experimental accuracy amounting to 1.25 x 10(-4). However, in the general case, a significant portion of the NWs is coalesced, generating an average tensile strain that can be partly released by detaching the NWs from their substrates. It is concluded that at the scale of the single NW, the free surface and the residual doping do not generate a significant strain and only coalescence does. Published by AIP Publishing.

Keywords: Molecular-Beam Epitaxy; Raman-Scattering

Domains: Physics [physics]

Thomas Auzelle, Xavier Biquard, Edith Bellet-Amalric, Zhihua Fang, Herve Roussel, et al.. Unraveling the strain state of GaN down to single nanowires. Journal of Applied Physics, 2016, 120 (22), pp.225701. ⟨10.1063/1.4971967⟩. ⟨cea-01849345⟩