Synthesis、Characterization And Properties Of Large-area Silicon Nanotip Arrays

One-dimensional nanoscale wires, tubes and tips have attracted considerableattentions due to their novel optical and electronic properties in recent years. Thesuccessful synthesis of carbon nanotubes has stimulated much research interest innanomaterials especially in semiconducting nanaostructures, such as Silicon, ZincOxide, etc. Silicon, which is plentiful and ubiquitous, generally stable, nontoxic,remains the most important material for current semiconductor industry. For this reason,Silicon nanomaterials especially Silicon nanowires (SiNWs) are widely considered asan important class of nanoscale building blocks for high-performance devices, such asfield-effect transistors (FETs), energy conversion and storage, as well as biological andchemical sensor devices. Attribute to the imperfection of exsiting technology andpractical research for preparing silicon nano wire array, this research is aimed to achievesimple and cheap preparing approach so that the preparing method, interactivemechanism and practical research of silicon nano wire array will be more flawless.1. A novel strategy for preparing large-area, vertically aligned Silicon nanotiparrays at near room temperature by combining silver mirror reaction withmetal-catalyzed electroless etching (MCEE) has been developed. It has beendemonstrated that the Silicon nanotips arrays with a length among4-7μm and middlepart diameter ranges from100to300nm have been successfully fabricated on Siliconwafers. Different from other etching approaches, Ag nanoparticles whose thicknessranging from50-100nm were deposited on Si wafers via silver mirror reaction first, andthen Ag-covered Si substrates were immersed into HF-H2O2solution to obtain thelarge-area vertically aligned Si nanotips arrays. This method is considerably simple,efficient, nontoxic, controllable and low-cost. Moreover it doesn’t need hightemperature, complicated equipments and demanding conditions of environment.2. After studying different sets of parameters’ effect on the micro morphology ofsilver nanoparticles and silicon nanotip array, the best ones are as follow: silver mirrorreaction tempreture and time are:50and1min, respectively, etching time is60min.Furthermore, the effect of etching time on the depth of silicon nanotip array has also been investigated. The depth will grow larger with etching time increasing. Besides, theconformation mechanism of silicon nanotip array has been studyed as well.3. At last, the field emission property of the Si nanotip array was primally tested.The conclusions are as follow: effective electron emission can be abtained by the Sinanotip array which fabricated by us; the turn-on field is2.7V/μm (defined as theelectric field required to extract a current density of10μA/cm2). The field enhancementfactors determined using the F-N plot is692. Meanwhile, the Silicon nanotips filmsshow very low reflectance (<10%at300-800nm) and a great strong broadband inoptical absorption (>90%at500nm).In this paper, a new method used to fabracate large-area silicon nanotip arrays wassuccessfully developed, the influence factors of preparation process and preliminaryapplication were studied. The resultant large-area vertically aligned Si nanotips arrayson Si substrate can be expected to be used on field-emitting applications and solar cellsin the future and it will have broad prospects for development.