GaAs/Si buffer structures grown by metal-organic chemical vapor deposition

GaAs buffer layers with thicknesses ranging from 1 to 5.3 $\mu$m were grown on Si substrates by metalorganic chemical vapor deposition. It is shown that the threading dislocations density decreases to 4$\Omega$10$^7$ cm$^{-2}$ with an increase in the GaAs buffer layer thickness up to 5.3 $\mu$m. The root mean square surface roughness reaches its minimum value of 2.2 nm at a GaAs buffer layer thickness of 1.6 $\mu$m.