Ge_1-y Sn_y Si (100) composite substrates for growth of Inx Ga_1-x As and Ga As_1-x Sb_x alloys

We describe unique methodologies for integration of Inx Ga1-x As and Ga As1-x Sbx semiconductor alloys with Si involving an innovative buffer layer approach based on lattice-engineered Ge1-y Sny alloys. These are grown strain-free on Si(100) via formation of Lomer edge dislocations and exhibit a continuous selection of lattice parameters higher than that of Ge. This allows close lattice matching with the Inx Ga1-x As and Ga As1-x Sbx compounds, thereby providing a manifestly different approach to the integration of mismatched III-V semiconductors with silicon. A series of compositions across the entire alloy range were grown for both systems using metal organic chemical vapor deposition at low temperatures between 500-550 °C. The materials displayed high quality morphological, structural, and optical properties as evidenced by Rutherford backscattering spectroscopy, ion channeling, cross sectional transmission electron microscopy, atomic force microscopy, and photoluminescence characterizations. High resolution x-ray diffraction measurements indicated that the films grow with much less strain than those grown on conventional substrates.