HETEROINTERFACE STUDY OF PERTURBED LPE GROWTH OF ALGAAS INGAP SINGLE HETEROSTRUCTURE

This paper presents the perturbed growth of Al0.7Ga0.3As/In0.5Ga0.5P single heterostructure on a GaAs substrate by liquid-phase epitaxy. The AlGaAs-InGaP heterointerface was characterized by scanning electron microscopy, photoluminescence, Auger electron spectroscopy, and transmission electron microscopy. Evidence is provided showing that a small amount of droplets, after the slider operation of the In0.5Ga0.5P epitaxial growth, mixed with the Ga-rich AlGaAs melt, is sufficient to attack the In0.5Ga0.5P underlying layer. Even with complete melt removal, there is still a partial dissolution at the "flat" Al0.7Ga0.3As-In0.5Ga0.5P heterojunction. The Auger depth profiles reveal the composition-depth transition width at this interface to be 560 angstrom from the 90%-10% of Al (or Ga, As, and In) Auger profile; however, the P atoms penetrate deeply into the Al0.7Ga0.3As layer due to the partial dissolution of In0.5Ga0.5P layer. By high-resolution electron-micrograph analysis, some dislocations are observed at the heterojunction leading to nonradiative recombination and to poor optical device performance, even though the heterointerface observed by scanning electron microscopy is very flat.