Low Temperature Synthesis of Silicon Oxide Nanowires

Silicon Nanowires (SiNWs) have many potential applications that include diodes, transistors, logic gates, circuitry, and sensors. SiNWs also open the possibility for integrating optoelectronics with microelectronics, since silicon has semiconducting properties and amorphous silicon nanowires have been shown to emit blue light. It has been demonstrated that SiNWs have tunable electrical properties, depending on the dopant used. With such a range of applications, the ability to mass-produce silicon nanowires simply and easily with no other source of silicon needed other than the substrate itself will prove very useful. Such methods have previously been reported, but our method involves production of the SiNWs at a lower temperature than those widely observed. A (100) silicon substrate was cleaned for five minutes each in ethanol followed by acetone. Films with thicknesses of less than 20 nm of either gold or 60/40 gold/palladium were deposited on the substrate through physical vapor deposition to serve as the growth center for the SiNWs. The samples were placed in a furnace and annealed to 900° C, under a 1500 sccm flow of argon at atmospheric pressure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for characterization of the SiNWs. The resulting SiNWs were amorphous in structure and very convoluted, with lengths on the order of tens of microns, diameters of 40 nm and a bed thickness of approximately 10 m. The effect of varying gold concentration, annealing time, temperature, and gas flow rate were then investigated. The results, which will be discussed in further detail, indicate that adjusting these parameters allows for control over the length, thickness, density, and morphology of the nanowires.