Thermal degradation effects in InP

Thermal degradation in InP has been regarded to be equivalent to surface deformation. By means of luminescence microscopy the authors discovered a much larger scale of degradation effects. Crystallographic defects of several geometrical characteristics have been observed although the surfaces seemed to be perfectly smooth. The standard methods of protection against degradation used in liquid phase epitaxy turned out to be unreliable concerning the invisible degradation effects. The authors propose a model which describes the evolution of degradation starting with invisible crystallographic defects. An extreme loss of phosphorus concentrated around dislocations causes local melting representing the final and visible stage of degradation. It is supposed that P vacancies which have never been noticed before are responsible for inhomogeneities affecting processing and the reliability of optoelectronic devices.