TRANSMISSION ELECTRON-MICROSCOPY CHARACTERIZATION OF IN1-XGAXSB ON (001) GAAS HETEROEPITAXIAL SYSTEM

Seven In1-xGaxSb (0 less-than-or-equal-to x less-than-or-equal-to 1) f ilms grown on a (001) GaAs substrate by metalorganic magnetron sputter ing were characterized using cross-sectional transmission electron mic roscopy techniques. Analysis included high-resolution and diffraction contrast imaging, selected area diffraction, and energy dispersive X-r ay methods. The epilayers were not observed to possess significant amo unts of large-scale residual strain owing to the lattice mismatch; how ever, 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 6 0 and (or) 90-degrees dislocations, the distributions of which were fo und to obey the Frank-Bilby equation for epitaxial systems. Epilayer t ilting was observed in the heteroepitaxial systems that possessed a si gnificant substrate inclination. The magnitude and direction of the fi lm tilt, to a first approximation, appeared to be associated with the particular distribution of 60-degrees dislocations observed at the int erface. Also, it was observed that surface roughness of the substrate can lead to grain boundaries in the films. Finally, growth defects, sp ecifically stacking faults and threading dislocations, were present in qualitatively varying degrees in the films studied.