Self-Organized Si Nanowires with Room-Temperature Photo-Emission

Two-dimensional arrays of self-organized Si nanowires were synthesized using the metal induced growth (MIG) method. In MIG processing, the thermally evaporated 25∼100 nm thick Ni films serve as prelayers for magnetron sputtered Si. When sputtering at 550°C, the Si crystallization occurs via the formation of nickel disilicide followed by subsequent epitaxial growth of Si crystals on nickel disilicide due to an extremely small lattice mismatch. Scanning electron microscopy study showed that the nanowires originated from the Si thin film and grew upwards in bundles. The diameter of the nanowires was 20∼50 nm. The length of the nanowires was typically 1 νm. Transmission electron microscopy and electron diffraction analysis revealed the single crystal structure of nanowires. Quantum-size effects in the produced wires were investigated by measuring the photoluminescence spectra at both low and room temperature. An intense room temperature PL peak centered around 690 nm with FWHM of 180 nm showed the promise of MIG-Si nanowires for red light-emitting diode applications. In addition, self-aligned silicide film on the bottom provides an ultimate back Ohmic contact, which significantly simplifies the fabrication of optoelectronic devices