Characterization of interfacial atomic steps in GaAs/AlAs superlattices by transmission electron microscopy

Abstract
We have studied interfacial atomic steps in GaAs/AlAs superlattices using high-resolution transmission electron microscopy (HRTEM) and lattice image simulation. We find arrays of bright spots at the interface in the TEM image to be good indicators of the interface configuration. Doubling of the bright spot arrays and step-shaped arrays in TEM lattice images indicate a ‘‘type 1’’ monolayer step whose front is perpendicular to the direction of the electron beam and a ‘‘type 2’’ monolayer step whose front is parallel to the direction of the electron beam. Our HRTEM observations indicate that the atomic steps at GaAs and AlAs interfaces grown at 700 °C are denser than at interfaces grown at 500 °C.