Si-Based Nanoscale Island Array and its Related Nanostructures for Nanoelectronics and Nano-Optoelectronics

Porous anodic alunlina (PAA) with highly ordered pore arrangenlent, controllable pore dianleter, channel length, and fine insulating property is widely used as a tenlplate to grow nanowires or nanotubes since the pioneering work of Martin et aI. The self-organization nlechanisnl to achieve an ordered nanopore arrangenlent is still a problenl and a better understanding is vital to applications such as self-assenlbled nano-electronic quantunl conlputers. Si-based nano-island arrays were fabricated on porous anodic alumina (PAA) by two methods. In the first method, a thick silicon film was deposited onto the surface with a highly ordered bowl array prepared by anodization of an Al foil, followed by the formation of a polycrystalline silicon nano-island array on the surface close to the bowl array after aluminum dissolution. In the second method, porous anodization was performed on an Al thin film on Si and a Si02 nano-island array was subsequently formed electrochemically. Time-resolved atomic force microscopy (AFM) and photoluminescence (PL) were used to investigate the growth process as well as nlechanisnl. Two applications of the nanoscale islands are presented. A novel nano-MOS array: nletallk carhon IHl..notllhe connecterl with nanoscale Si02 island inside insulated alumina nanochannel based on silicon substrate was fabricated via a Si-based PAA template. The electrical properties were determined by I-V and C-V measurements. The lower work function of the multiwalled CNTs induces lower flat-band voltages (VFB) compared to the conventional behavior of MOS. This structure is important for CNTs and PAA template via the self-assenlbled nlechanisnl in nanoelectronics. The second exanlple is Cu oxide nanowire array fabricated on Si-based Si02 nanoscale islands via nanochannels of a Si-based porous anodic alumina (PAA) tenlplate at roonl tenlperature under a pulse voltage using copper electrodeposition. X-ray diffraction and photoelectron spectroscopy show that the oxide nanowire is Cu20. The nanowires exhibit a preferential growth direction (111) and are interconnected with the nanoscale Si02 islands as confirnled by translnission electron microscopy (TEM). The formation of Cu20 is due to the alkalinity of the anorli7,ed solution. However, the oscillations of the potential and current during the experinlent tend to result in a snlall anlount of copper and CuO in the nanowires. The cathodoluminescence (CL) data show that the energy level is larger than the bandgap of Cu20 because of quantunl confinelnent effects.