Zhang Bo-Rui

Synthesis and PL Properties of ZnSe Nanowires with Zincblende and Wurtzite Structures

Single crystalline ZnSe nanowires with both zincblende and wurtzite structures have been synthesized via a chemical vapour deposition method under different growth conditions. The nanowires are usually 50–80 nm in diameter, and several tens of microns in length. Room-temperature photoluminescence spectra from zincblende and wurtzite ZnSe nanowires show a broad luminescence band peaked at around 2.71 eV and a deep level emission band peaked at around 2.00 eV, respectively. Effects of post-growth annealing on the photoluminescence of these nanowires have been investigated. Strong room-temperature band-edge emission could be obtained from the annealed zincblende ZnSe nanowires.

Electroluminescence and photoluminescence from scored Si-rich SiO2 film/p-Si structure

Electroluminescence (EL) is observed from the Au/Si-rich SiO2 film/p-Si diodes, in which the Si-rich SiO2 films are scored deliberately by a diamond tip. The EL intensity of the scored diode annealed at 800 degreesC is about 6 times of that of the unscored counterpart. The EL spectrum of the unscored diode could be decomposed into two Gaussian luminescence bands with peaks at about 1.83 and 2.23eV, while for the EL spectrum of the scored diode, an additional Gaussian band at about 3.0eV appears, and the 1.83-eV peak increases significantly in intensity. The photoluminescence (PL) spectrum of an unscored Si-rich SiO2 film has only one band peaking at about 1.48eV, whereas the PL spectrum of the scored one has two bands at about 1.48 and 1.97eV. We consider that the high-density defect regions produced by the scoring provide new luminescence centres and become some types of nonradiative centres in the Si oxide layer, which thus result in changes of the EL and PL spectra.

Photoluminescence and Photoluminescence Excitation of Si Aerogels Prepared by Supercritical Drying

Si aerogel, the porous silicon with ultra high porosity, has been prepared by the technique of anodization followed by supercritical drying. Its photoluminescence, photoluminescence excitation and morphological features exhibit novel characteristics from those of the conventionally anodized porous silicon. We observed the differences between the Si aerogels made from and crystalline Si.

EPR study of porous silicon

An anisotropic EPR signal was observed in porous Si. According to its symmetry andg value, the EPR signal can be attributed to silicon dangling bonds located on the surface of a porous Si skeleton. The evolution of the EPR signal at room temperature in air was measured. The annealing temperature dependence of the EPR and the PL of porous Si in oxygen and the effects of gamma irradiation on the EPR and the PL spectra of porous Si were studied. The changes of the EPR signal and the PL intensity induced in atmosphere by ethyl alcohol and acetone were discovered. The dangling bond is only one of the factors which affect the PL.

Gamma-Ray Irradiation Effects on Electroluminescence from Au/Extra Thin Si-Rich SiO2 Film/p-Si Structures

We have studied the effects of γ-ray irradiation on electroluminescence (EL) from Au/extra thin Si-rich SiO2 film/p-Si Structures. After γ-ray irradiation, for the structure with a 600°C annealed Si-rich SiO2 film a new blue EL band with a peak at around 480 nm was observed, and for the structure with a 300°C annealed Si-rich SiO2 film the red EL band shifts from 670 to 660 nm and its intensity and full width at half maximum increase pronouncedly. The experimental results demonstrate that the defects induced by γ-ray irradiation are responsible for the blue EL band as well as for the variations of the red EL band.