Transmission electron microscopy characterization of In1−xGaxSb on (001) GaAs heteroepitaxial system
Seven In1−xGaxSb [Formula: see text] films grown on a (001) GaAs substrate by metalorganic magnetron sputtering were characterized using cross-sectional transmission electron microscopy techniques. Analysis included high-resolution and diffraction contrast imaging, selected area diffraction, and energy dispersive X-ray methods. The epilayers were not observed to possess significant amounts of large-scale residual strain owing to the lattice mismatch; however, localized strain was apparent under diffraction contrast imaging in some films. High-resolution electron microscope analysis indicated that the interfacial lattice mismatch was accommodated by arrays of 60 and (or) 90° dislocations, the distributions of which were found to obey the Frank–Bilby equation for epitaxial systems. Epilayer tilting was observed in the heteroepitaxial systems that possessed a significant substrate inclination. The magnitude and direction of the film tilt, to a first approximation, appeared to be associated with the particular distribution of 60° dislocations observed at the interface. Also, it was observed that surface roughness of the substrate can lead to grain boundaries in the films. Finally, growth defects, specifically stacking faults and threading dislocations, were present in qualitatively varying degrees in the films studied.