Novel ordered aloetic-shaped SiC nanowires were synthesized on a Si (100) substrate by reacting methane with silicon dioxide using iron as a catalyst. Their structure and chemical composition were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The wires have a tapered aloetic structure with a top diameter about 50-80 nm and a length about 10 microm. The field emission properties of the aloetic nanowires were investigated. A stable emission with current density of 0.525 mA/cm2 at an applied electric field of 2.2 V/microm and a low turn-on electric fields of 1.4 V/microm were observed. The excellent field emission properties indicate that the aloetic-shaped SiC nanowires may have potential applications in flat panel displays and electron field-emitting devices.

Using standard photolithography,patterned carbon nanotube line arrays were fabricated on silicon substrates by thermal chemical vapor deposition.Scanning electron microscopy and Raman spectroscopy were used to characterize the structure of the carbon nanotubes.The carbon nanotubes were very uniform and about 50 nm in diameter and 2 μm in length.The Raman spectrum showed that the carbon nanotubes were multi-walled carbon nanotubes.Field emission characteristics of the samples were characterized.It was found that the non-patterned carbon nanotube films,10 μm and 2 μm size carbon nanotube line arrays field emission characteristics were gradually improved with turn-on field of 3 V/μm,2.1 V/μm,1.7 V/μm and emission current density at applied electric field 3.67 V/m were 2.57 mA/cm2,4.65 mA/cm2,7.87 mA/cm2,respectively.The reasons may attribute to the field-screening effect and edge effect by analyzing the experimental results.

The variable-temperature photoluminescence spectra of strained InAsxP1-x/InP heterostructuer were experimentally determined in the temperature range 13~300 K.A theoretical calculation was presented that takes into account the temperature-induced variations in band gap and biaxial strain to explain the PL spectra.The results showed that strain which is induced by lattice mismatch between epitaxial layer and substrate removes the degeneracy between the light-and heavy-hole states at the top of the valence band,and with temperature under 100 K,the recombinations from the conduction band to the split valence bands are both observed in the photoluminescence spectra.As temperature is raised,it results in an increasingly larger light-hole population than that of heavy-hole due to thermalization,so when temperature is beyond 100 K only the recombination from the conduction band to the light-hole state can be observed.We also find that the energy of the recombination between the conduction band and the light-hole and heavy-hole state changes as a function of temperature.