Blue Luminescent Properties Of Silicon Nanowires Grown By Au Catalytic Method Based On Solid-liquid-solid Mechanism

Silicon nanowires (SiNWs) are typical quasi-one-dimensional nanostructures, its photoluminescence (PL) properties have potential applications in the field of Si-based optoelectronic devices. Si nanowires was grown on n-(111) Si, poly-Si and quartz substrates by using a thin layer of gold acts as metallic catalyst, and were annealed at high temperature based on solid-liquid-solid(SLS)mechanism. The diameters were several nanometers and the lengths were up to several microns to tens of microns. The samples were characterized by scanning electron microscopy (SEM), energy -dispersive X-ray spectrometry (EDS) ,and the PL properties of SiNWs are observed by FLS920 spectrometer. The PL spectra of the SiNWs exhibit a strongly blue luminescent band in the wavelength range of 400-480nm, which emission peak is located at 420 nm, and also a weak red luminescent band in the wavelength range of 600-650nm, which emission peak is located at 625nm. The light-emitting mechanism is discussed. The blue luminescence band is attributed to the oxygen-related defects, which are oxygen vacancies located at SiOx amorphous oxide shells around the crystalline core of SiNWs.The weak red luminescence results from the Si=O double band states or nonbridging oxygen hole center (NBOHC) located at inferfacial regions. The SiNWs are oxidized at 1000℃for different times. The influence of oxidation treatment on the PL propertis has been studied. Doping of SiNWs is achieved by post-diffusion method. The influence of different doping time and temperatures on PL properties of SiNWs has been studied. The Si nanowires are also synthesized on poly-Si, quartz and SiO₂ by the same method. The PL are studied on those different substrates.