High quality GaAs on Si using Si0.04Ge0.96/Ge buffer layers
High-quality epitaxial growth of GaAs on Si has been achieved using Si0.04Ge0.96/Ge buffer layers. GaAs layers, approximately 1.3 ?m thick, have been grown on Si using interfaces of Ge/Si0.04Ge0.96 layers to confine the majority of misfit dislocations that are generated by the 4% lattice mismatch between Ge and Si. The GaAs layers, grown by organometallic vapor phase epitaxy (OMVPE), have background carrier concentrations of 2×1015 cm-3. Transmission electron microscopy (TEM) indicates dislocation densities as low as 107 cm-2 in the GaAs layers. A photoluminescence-decay measurement on an AlGaAs/GaAs double heterojunction (DH), grown on a (100)-oriented Si substrate and the Si0.04Ge0.96/Ge buffers, yields a minority-carrier hole lifetime of 2.5 ns which is state-of-the-art for heteroepitaxial GaAs on Si. This value represents a significant development for a novel approach in the heteroepitaxy of GaAs on Si.