Light-emitting silicon nanowires obtained by metal-assisted chemical etching. (22nd March 2017)

• Record Type: Journal Article
• Authors: Irrera, Alessia; Lo Faro, Maria Josè; D'Andrea, Cristiano; Alessio Leonardi, Antonio; Artoni, Pietro; Fazio, Barbara; Anna Picca, Rosaria; Cioffi, Nicola; Trusso, Sebastiano; Franzò, Giorgia; Musumeci, Paolo; Priolo, Francesco; Iacona, Fabio
• Is Part Of: Semiconductor science and technology. Volume 32:Number 4(2017:Apr.)
• Publication Date: 2017-03-22
• Subjects: Si nanowires -- photonic applications -- photoluminescence -- metal-assisted chemical etching -- Raman spectroscopy -- electroluminescence -- pulsed laser deposition; Semiconductors -- Periodicals; 621.38152
• DOI: 10.1088/1361-6641/aa60b8
• Languages: English
• ISSNs: 0268-1242

Abstract

Abstract: This review reports on a new process for the synthesis of Si nanowires (NWs), based on the wet etching of Si substrates assisted by a thin metal film. The approach exploits the thickness-dependent morphology of the metal layers to define uncovered nanometric Si regions, which behave as precursor sites for the formation of very dense (up to 1 × 10 12 NW cm −2 ) arrays of long (up to several μ m) and ultrathin (diameter of 5–9 nm) NWs. Intense photoluminescence (PL) peaks, characterized by maxima in the 640–750 nm range and by an external quantum efficiency of 0.5%, are observed when the Si NWs are excited at room temperature. The spectra show a blueshift if the size of the NW is decreased, in agreement with the occurrence of quantum confinement effects. The same etching process can be used to obtain ultrathin Si/Ge NWs from a Si/Ge multi-quantum well. The Si/Ge NWs exhibit—in addition to the Si-related PL peak—a signal at about 1240 nm due to Ge nanostructures. The huge surface area of the Si NW arrays can be exploited for sensing and analytical applications. The dependence of the PL intensity on the chemical composition of the surface indeed suggests interesting perspectives for the detection of gaseous molecules. Moreover, Si NWs decorated with Ag nanoparticles can be effectively employed in the interference-free laser desorption-ionization mass spectrometry of low-molecular-weight analytes. A device based on conductive Si NWs, showing intense and stable electroluminescence at an excitation voltage as low as 2 V, is also presented. The unique features of the proposed synthesis (the process is cheap, fast, maskless and compatible with Si technology) and the unusual optical properties of the material open the route towards new and unexpected perspectives for semiconductor NWs in photonics.