Quality-enhanced GaAs layers grown on Ge/Si substrates by metalorganic chemical vapor deposition

High-quality GaAs layers were grown on Si substrates by low-pressure metalorganic chemical vapor deposition. Double crystal X-ray diffraction measurement shows that the structural properties of GaAs layers are so much improved by 5 μm thick Ge buffer layer and InGaAs/GaAs strained-layer superlattice. The X-ray full-width at half-maximum of the (4 0 0) reflection obtained from 2 μm thick GaAs is 98 arcsec, one of the smallest value ever reported. The surface dislocation density of the GaAs layer estimated by molten KOH study is as low as 4 × 10⁵ cm^-2. Photoluminescence and Raman measurements confirm the good optical quality of the heteroepitaxial GaAs epilayer.