ELASTICALLY STRAINED INGAASP FILMS GROWN BY LPE AND CONCEPTION OF STRESS-INDUCED SUPERCOOLING

The pseudomorphic InGaAsP films with elastic strains up to 1% are grow n on GaAs substrates of (111)B orientation by liquid phase epitaxy (LP E). The evolution of morphology with an increase of elastic strain in the films is analysed. A new mechanism of elastic strain relaxation du ring InGaAsP film growth is discovered. It consists in the appearance of unstrained islands in the InGaAsP strained film and their lateral s preading till they come together. The fundamental limit of elastic str ains to about 1% in the InGaAsP films grown by LPE is connected with t he stress-induced supercooling that appears and increases with the str esses in the film and, at last, compensates the initial supercooling o f the liquid. The time required for the growth of the elastically stra ined films does not exceed a few seconds. At longer duration of the gr owth unstrained parts of the film spread laterally and cover the whole surface of the substrate with a highly mismatched unstrained layer of poor crystal quality.