Observation of cellular structures of defects in semi-insulating InP-Fe

• Published in: Solid state communications 1987, Vol.64 (9), p.1243-1246
• Main Authors: Fillard, J.P., Baroudi, A., Gall, P., Bonnafe, J., Favennec, P.N., Coquille, R.
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Defects and impurities in crystals; microstructure; Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.); Exact sciences and technology; Physics; Structure of solids and liquids; crystallography
• ISSN: 0038-1098; 1879-2766
• DOI: 10.1016/0038-1098(87)90741-1

It is known that GaAs semi-insulating materials reveal an organization of defects which appears in (0 0 1) wafers as a pattern of cells. This typical arrangement is displayed in surface etchpit images as well as X-ray topographies, infrared transmission and so on. It is shown here that a similar organization also exists in InP wafers: its visualization is not easy because of a very weak contrast in the image: their observation requires a strong contrast enhancement by numerical processing. The structure could be related to entangled dislocations along shear stress planes resulting from the post growth cooling process. These dislocations are weakly decorated, may be with small aggregates of Indium atoms which are widely separated. They are observed as very bright points in laser scanning tomography. These cellular patterns are not as dependent on the origin of the crystal and the typical average dimensions are in the range of 200–300 μm (similar to GaAs) which means that they luckily fit within the dimensions of most of the optoelectronic integrated circuits. The macrospecific arrangement of cells does not display the tetragonal symmetry often observed on GaAs materials.