EELS and STEM Assessment of Composition Modulation in InAlAs Tensile Buffer Layers of InGaAs /InAlAs /(100)InP Structures

Abstract

In previous work, InGaAs single quantum well structures had been grown on (100) InP, 4° misoriented towards (111). Transmission electron microscopy had shown that the misorientation of the substrate gave rise to a development of lateral contrast modulation that initiated on the InAlAs tensile buffer layer, and it was suggested that contrast modulation could be related to In-rich or Al-rich regions. In the present work, contrast modulation has also been observed in high angle annular dark field imaging; an electron energy loss spectroscopy study of the evolution of plasmon position also supports the hypothesis of compositional modulation.