Arrayed Nanoporous Silicon Pillars
Si-based nanosystems have attracted much attention because of their unique nanostructures and unusual physical properties that might be applied in areas as diverse as optoelectronics, single electron devices, sensors, detectors, and cold cathodes for šeld-emission displays (Canham 1990, Bisi et al. 2000, Birner et al. 2001, Bettotti et al. 2002, Shang et al. 2002, Fujita et al. 2003, Scheible and Blick 2004, Garguilo et al. 2005, Heitmann et al. 2005, Kanechika et al. 2005, Shao et al. 2005). ™e fabrication of the high-performance šeld-e£ect transistors based on n-type Si nanowires (Zheng et al. 2004) and piezoelectric nanogenerators based on zinc oxide nanowire arrays (Wang and Song 2006) are two of the most exciting examples to demonstrate the importance of Si-based nanostructures in developing optoelectronic nanodevices. In the past decade, various interesting Si nanostructures, such as porous Si (PS) (Canham 1990, Cullis et al. 1997, Bisi et al. 2000, Birner et al. 2001, Bettotti et al. 2002), arrays of nanocones (Shang et al. 2002), nanopillars (Scheible and Blick 2004), nanorods (Cluzel et al. 2006), and nanowire p-n junction diodes (Peng et al. 2005), etc., were prepared and their unique optical or electrical properties were observed. Nevertheless, considering the role played by Si in modern microelectronics and its potential application in
future nanoelectronics, the space for preparing novel Si nanostructures with enhanced physical properties should still be tremendous.