The thermal stability of oxygen precipitates formed by prolonged annealing at 1000℃ in conventional Czochralski silicon and nitrogen-doped Czochralski silicon has been comparatively investigated. It was found that a majority of the existing oxygen precipitates in the nitrogen-doped silicon were dissolved by both conventional furnace annealing and rapid thermal annealing at 1200℃, while those in the conventional Czochralski silicon dissolved at 1250℃, as a result of nitrogen enhancing denser oxygen precipitates with smaller size. Furthermore, it can be considered that the dissolution of oxygen precipitates is primarily determined by the annealing temperature.

Ordered silicon nanowires (SiNWs) with single crystal structure were synthesized using nanochannel-Al2O3 (NCA) and the chemical vapor deposition (CVD) method. Firstly, the SiNWs with nearly amorphous structure were fabricated at 500℃; then the SiNWs with crystalline structure were obtained by annealing an as-received sample at 800 C. The average diameter and length of the SiNWs are 40-70 nm and 10 mm, respectively. The Raman shift related to the crystallization and the amorphous SiNWs was analyzed.

Tiny SiO2 nano-wires (SiO2-NWs) were synthesized on a p-Si (1 1 1) wafer by the chemical-vapor-deposition method. The minimum diameter of the nano-wires was around 9 nm, and the length was longer than 10μm. The results of transmission electron microscopy shows that the amorphous nano-wires were composed of Si and O with an approximate atomic ratio of 1:2. Furthermore, the photoluminescence behavior of the SiO2-NWs has been also checked.

CdS nanotubes have been prepared by means of chemical bath deposition (CBD) and nanochannel alumina (NCA) template. X-ray diffraction (XRD) and selected area electron diffraction (SAED) indicate that the nanotubes are of cubic structure. Transmission electron microscopy (TEM) shows the diameters of nanotubes are around 50nm. Furthermore, high-resolution TEM (HRTEM) reveals a clear lattice image of {1 1 1} planes in the wall of a CdS nanotube. The directional growth of nanotubes is verified by scanning electron microscopy (SEM). It can be expected that the method presented in this letter is also appropriate for the preparation of nanotubes of other semiconductors.

It is reported that a normal InGaAs laser diode (LD) operating at 980 nm possesses a second harmonic at 490 nm and a strong deep-UV emission at room temperature. By comparing with the radiation from cadmium sulphide (CdS) nanoparticles and nanowires, it is found that the UV emission from the LD can be attributed to a characterized radiation of nanoscaled semiconductors. By doping different semiconductor nanomaterials into the active layers of the LD and taking some effective techniques, such as cavity optimization, the avelength, and the power output of the UV emission could be adjusted.