Dong Guo-yi

Measurement of the time-resolved spectrum of photoelectrons from ZnS:Mn, Cu luminescent material

The process of decay of photoelectrons in the conduction band of ZnS:Mn, Cu luminescent materials after excitation with a short-pulse laser has been investigated in this paper by means of measurements made using the microwave absorption dielectric spectrum detection technique. Exponential decay processes were observed for the electrons in the conduction band and the shallow-trapped electrons; the lifetimes of the electrons were found to be 1177 and 1703 ns, respectively. The processes of decay of the luminescence from ZnS:Mn, Cu were investigated and exponential decay processes were found for blue Cu+, green Cu+ and Mn2+ luminescent centres with lifetimes of the excited state of 139, 140 and 680 µs, respectively.

Photoluminescence Mechanism of ZnO:Zn Investigated by Microwave Dielectric Spectrometry

We investigate the decay process of photoelectrons from a luminescent material of ZnO:Zn using a microwave dielectric spectrometry. Electrons in the conduction band are found to decay exponentially and the lifetime is 781 ns, while the time interval of decay from the maximum to half of this value is 470 ns. ZnO:Zn is a green luminescent material at its central wavelength of 510 nm. Compared to the decay of electrons in the conduction band, the decay process of the luminescence is faster, and the time interval of decay from the maximum to half of the maximum is about 100 ns. We believe that the mechanism of the ZnO:Zn visible luminescence is recombination luminescence, and find that our theoretical simulation is in agreement with the experimental results.

Monte Carlo simulation of the behaviour of electrons during electron-assisted chemical vapour deposition of diamond

The behaviour of electrons during electron-assisted chemical vapour deposition of diamond is investigated using Monte Carlo simulation. The electron energy distribution and velocity distribution are obtained over a wide range of reduced field E/N (the ratio of the electric field to gas molecule density) from 100 to 2000 in units of 1Td = 10-17Vcm2. Their effects on the diamond growth are also discussed. The main results obtained are as follows. (1) The velocity profile is asymmetric for the component parallel to the field. The velocity distribution has a peak shift in the field direction. Most electrons possess non-zero velocity parallel to the substrate. (2) The number of atomic H is a function of E/N. (3) High-quality diamond can be obtained under the condition of E/N from 50 to 800Td due to sufficient atomic H and electron bombardment.