Convergent Beam Electron Diffraction and Transmission Electron Microscopy Study of Interfacial Defects in Gallium Nitride Homoepitaxial Films

Conventional and high resolution electron microscopy have been applied to characterize the microstructure of the CrAs-GaAs eutectic. The CrAs-GaAs eutectic crystals were directionally solidified by the Czochralski method in order to produce an ordered array of CrAs rods embedded in a GaAs matrix. The CrAs rods of 2-3 μm in diameter align parallel to the growth axis of the ingot. Where the GaAs matrix is found to contain structural defects, the CrAs rods are effectively defect-free. The CrAs has an orthorombic structure with the parameters a=3.5±0.1 Å, b=6.2±0.1 Å,c=5.7±0.1 Å.The c-axis is close to the direction of solidification.

Carbon implantation was performed after high dose(5 x 1016/cm2) Ge implantation into [100] oriented Si substrates to study the effect of sequential implantation on dislocation nucleation. When the nominal peak concentration of implanted C is over 0.55 at%, Dislocations in the SiGe layer containing C are considerably reduced in density after solid phase epitaxial(SPE) annealing at 800°C for 1 hour, compared to the SiGe layer without C. These results suggest that during annealing, C atoms compensate the Geinduced misfit strain which causes dislocation generation in the region of peak Ge concentration. Channeling spectra obtained by RBS analysis show only 5% to 6% minimum back scattering yield as C atoms suppress the dislocation generation.

The clustering of isolated interstitial silicon, implanted atoms, and vacant lattice sites produced by low temperature and room temperature ion implantation during subsequent annealing is reviewed. An electron microscope method for studying the kinetics of the amorphous to crystalline transformation in silicon is described. The technique is applied to measurement of the activation energy for interface migration and the formation of microtwins for different growth directions. A very brief review of the effects of laser annealing after ion implantation is included.