Residual stresses and clamped thermal expansion in LiNbO3 and LiTaO3 thin films Appl. Phys. Lett. 101, 122902 (2012) Tribological properties of nanocrystalline diamond films deposited by hot filament chemical vapor deposition AIP Advances 2, 032164 (2012) The combined effect of surface roughness and internal stresses on nanoindentation tests of polysilicon thin films J. Appl. Phys. 112, 044512 (2012) Mechanism for atmosphere dependence of laser damage morphology in HfO2/SiO2 high reflective films Finite element ͑FE͒ analysis and transmission electron microscopy ͑TEM͒ observations have been used to model stress relaxation in InAs quantum dots deposited on ͑001͒ GaAs. TEM observations show that these islands are coherently strained and the corresponding strain contrast is simulated using the dynamical electron diffraction contrast theory. The dot strain fields used for the TEM contrast simulations are deduced from FE calculations. These calculations show that elastic stress relaxation mainly occurs at the crest of the island and that the underlying substrate is under tension. That experimental TEM images and simulated images should match shows that the FE method of determination of the dot strain fields is valid ͑even in the case of microscopic objects͒, and that the shape of islands can be specified.

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The device originally designed by Griggs and Kennedy in order to deform minerals under confining pressure is adapted for the study of the low temperature plasticity of semiconductors. The new device is less versatile but much more simple. It can be used in a range of low temperatures (20 t o 200 "C) and u p t o a pressure of 0.9 GPa. The solid confining medium is made of lead and silicone rubber. As friction forces are reduced to approximately 1 kN, stress-strain curves can be obtained with a high resolution. Finally the first applications t o the study of the low temperature plasticity of gallium arsenide are reported.Le montage de deformation sous pression de confinement conTu par Griggs et Kennedy a At6 adapt6 Q 1'8tude de la diformation plastique des semi-conducteurs B basse temphrature. Le nouvel appareillage est moins versatile mais beaucoup plus simple d'emploi. I1 peut &re utilish jusqu'Q une pression de 0,9 GPa dans une gamme de temperature de 20 Q 200 "C. Le milieu de confinement est constitub de plomb e t de silicone. Les forces de friction sont suffisamment basses (de l'ordre de 1 kN) pour obtenir des courbes de contrainte-deformation avec une excellente rhsolution. Enfin, les premiers resultats sup 1'6tude de la plasticiti B basse temp6rature de I'arseniure de gallium sont pr6sent6s.

To cite this version:A. Lefebvre, P. François, J. Di Persio. Transmission electron microscopy of semi-insulating Ga As deformed at room temperature and under confining pressure.Résumé. 2014 Des échantillons de Ga As sont déformés à température ambiante et sous une pression de confinement de 600 MPa. Deux mécanismes de deformation plastique sont proposés. Le premier s'appuie sur l'observation de dislocations 03B1 parfaites ou peu dissociées très mobiles. Le second mécanisme fait intervenir des dislocations 03B2 (ou vis) largement dissociées et moins mobiles. La dissociation de ces dislocations pourrait être due à une mobilité plus faible des dislocations partielles 30° (03B2).Abstract. 2014 Ga As single crystals have been deformed by compression at room temperature under a confining pressure of 600 MPa. Two competitive mechanisms of plastic deformation are proposed. The first mechanism is supported by the observation of mobile perfect (or slightly dissociated) 03B1 dislocations. The second mechanism involves less mobile widely dissociated 03B2 (or screw) dislocations. It is suggested that the large dissociation of these dislocations is due to the lower mobility of the 30° (03B2) partials.

Using a plane wave basis, we have solved numerically the Schrö dinger equation of the envelope function in the case of dislocation strain field binding potentials (deformation and piezoelectric coupling). Shallow one-dimensional bands are found for both electrons and holes, characterised by larger binding energies than those previously found by approximated analytical methods, 1D dislocation bands have also been computed and show a splitting of light and heavy hole bands resulting into four distinct bands.