TEM evaluation of stress and strain in III-V structures
|Andre Rocher , Martiane Cabie , Anne Ponchet|
CEMES, CNRS, BP 4347, F-31055 Toulouse, France, France
The stress and strain induced by a lattice mismatch between an epilayer and its substrate are known to control most of physical properties valuable for (opto)-electronic components. In good conditions of epitaxy and when no extended defects are seen, thin layers are considered as perfect, i.e. homogeneous and monocrystalline. This result is based on crystalline perfection of the structure: i) a sharp interface corresponding to a change of the chemical composition on one atomic plane; ii) an ideal film where all the deposited atoms take a strained position according to the elasticity theory. Within these conditions, the classical model is well established with applied strain fields directly defined by the continuity of the atomic planes through the interface. From this approach, below the critical thickness, 10 nm for 1% lattice mismatch, an epilayer is considered as perfectly strained. This representation need to be verified experimentally. Classical methods of the strain field analysis are performed by diffraction techniques and the stress field is deduced from the strain using the standard elasticity theory. The Transmission Electron Microscope (TEM) is a tool well adapted for this evaluation.
Presentation: invited oral at E-MRS Fall Meeting 2003, Symposium C, by Andre Rocher
See On-line Journal of E-MRS Fall Meeting 2003
Submitted: 2003-05-13 09:29 Revised: 2009-06-08 12:55