TEM Investigation of Dislocation Loops in Undoped InGaAsP and InGaP Layers Grown by Liquid Phase Epitaxy

Undoped InGaAsP and InGaP layers grown on (001)-oriented GaAs substrates by liquid phase epitaxy have been investigated by transmission electron microscopy. Two types of dislocation loops are observed in the same crystals as follows: interstitial type Frank loops with Burgers vectors of a/3<111> and vacancy type prismatic loops with Burgers vectors of a/2<101>. Most are generated in the region near the interface between the epitaxial layer and the substrate.