Self-Catalyzed Epitaxial Growth of Vertical Indium Phosphide Nanowires on Silicon

Vertical indium phosphide nanowires have been grown epitaxially on silicon (111) by metalorganic vapor-phase epitaxy. Liquid indium droplets were formed in situ and used to catalyze deposition. For growth at 350 degrees C, about 70% of the wires were vertical, while the remaining ones were distributed in the 3 other < 111 > directions. The vertical fraction, growth rate, and tapering of the wires increased with temperature and V/III ratio. At 370 degrees C and V/III equal to 200, 100% of the wires were vertical with a density of similar to 1.0 x 10(9) cm(-2) and average dimensions of 3.9 mu m in length, 45 nm in base width, and 15 nm in tip width. X-ray diffraction and transmission electron microscopy revealed that the wires were single-crystal zinc blende, although they contained a high density of rotational twins perpendicular to the < 111 > growth direction. The room temperature photoluminescence spectrum exhibited one peak centered at 912 +/- 10 nm with a FWHM of similar to 60 nm.