Reduction in threading dislocation density in ge epitaxial layers grown on Si(001) substrates by using rapid thermal annealing

We investigated the effects of RTA (rapid thermal annealing) on Ge epitaxial layers grown on Si(001) substrates. We found that a high RTA temperature of up to 800 °C was more effective in reducing the threading dislocation density (TDD) in the Ge layer because dislocations with higher velocities were more easily annihilated with each other at higher temperatures. We also found that the TDD was reduced by using RTA at 800 °C, leading to improved crystallinity. As the number of RTA cycles was increased to 20, the TDD was further lowered to 3.5 × 10⁷ cm⁻². Moreover, the growth of GaAs on Ge/Si that had been RTA annealed ten times showed improved crystallinity and optical property.