Behavior of Misfit Dislocations in GaAs Epilayers Grown on Si at Low Temperature by Molecular Beam Epitaxy

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Abstract
The behavior of misfit dislocations in GaAs buffer layers grown on Si was investigated by the measurement of stresses using optical interferometry and X-ray diffraction. The buffer layers grown at 250°C with various thicknesses (0.05∼0.20 µm) were annealed at various temperatures (400∼600°C). The overlayers were grown at 300°C. With increasing annealing temperature or thickness, the stresses changed from compressive to tensile. The stress-free GaAs/Si wafer was produced with a 0.10-µm-thick buffer layer annealed at 500°C. These results indicate that in low-temperature growth, it is important to optimize both the annealing temperature and the thickness of the buffer layer. In addition, the asymmetric stresses were observed between [011] and [01̄1]. This asymmetry was caused by the difference in dislocation velocities or nucleation energies between α- and β-dislocations.