(527c) Self-Catalyzed Epitaxial Growth of Dislocation-Free Indium Phosphide Nanowires On Silicon

The successful integration of III-V materials onto silicon would make it possible to fabricate an array of new electronic and photonic devices with greater functionality and at a lower cost. However, growing compound semiconductors on silicon is extremely challenging due to the polar/non-polar interface and the large lattice mismatch between the materials. One method of managing the high density of defects generated at the interface is to deposit pseudomorphic buffer layers up to 5.0 microns thick before making the active device structure. We have investigated an alternative approach to this problem: Free standing nanowires of indium phosphide have been grown epitaxially on Si(100) and Si(111) by metalorganic vapor-phase epitaxy. Liquid indium droplets were used to catalyze crystal nucleation. High-resolution transmission electron micrographs revealed that the nanostructures fully accommodated the strain due to the lattice mismatch and formed interfaces with the silicon that were free of dislocations. The preferred growth orientation was along <111> crystal directions. On Si(111), 100% vertical nanowires were achieved at 370 °C and a V/III ratio equal to 200. The wire density was 1.0x10⁹ cm^-2, while the average dimensions were 3.9 μm in height, 45 nm in base width and 15 nm in tip width. X-ray diffraction and transmission electron microscopy showed that the wires were single-crystal zinc blende, although they contained a high density of rotational twins perpendicular to the <111> growth direction. Using triple-axis XRD, a rock curve width (FWHM) of only 42 arc-seconds was obtained. Room temperature photoluminescence spectra of the wires exhibited one peak centered at 912±10 nm. The prospects for using nanostructures to integrate III/V materials onto silicon will be discussed at the meeting.