Study of indium tin oxide thin films deposited on acrylics substrates by ion beam assisted deposition technique.

Indium tin oxide (ITO) thin films have been deposited onto acrylics (PMMA) substrates by ion beam assisted deposition technique at different oxygen flows. The structural, optical and electrical properties of the deposited films have been characterized by X-ray diffraction, transmittance, FTIR, ellipsometry and Hall effect measurements. The optical constants of the deposited films have been calculated by fitting the ellipsometric spectra. The effects of the oxygen flow on the properties of the deposited films have been studied. It has been found that 40 sccm oxygen flow is an optimum value for getting the films with good transmittance and low electrical resistivity.

[Study of color-changing device controlled by frequency and its mechanism].

Absorption is the underlying reason for the change in luminescence traits. And the lifetime influences the absorption in turn. This is a common law not only suitable for photoluminescence but also for other types of luminescence. In field emission display, two kinds of luminescence center have dramatically dissimilar lifetimes, which are co-doped in the same material. The spectrum changes with excitation frequency. Tuning color comes into reality in the same materials. The experiment proves that this law has something to do with lifetime, but has nothing to do with the way of excitation and the reasons for abruptly quenching.

[Simultaneous determination of rate ratio of recombination to capture and trap depth from thermo-luminescence of ZnS:Cu, Co].

The recombination luminescence is in nature a bimolecular process but, the decay rule may be changing from that of mono-molecular to bimolecular rule, i.e., from exponential to hyperbolic rule, depending on the behavior of conduction electrons. This behavior is represented by relative rate of recombination with ionized centers to that of capture by traps. This relative rate depends partly on the intrinsic parameters of the specified materials, and partly on the concentration of conduction electrons supplied by traps. Each point of the TL curve is related to the material parameters and the release of electrons from traps. The ratio of relative rate of recombination to that of capture gamma(epsilon) = sigma0(n0)/sigma(nu - n) involves the parameter epsilon. They are inseparable and must be determined at the same time. In the present report, starting from the same sample ZnS:Cu, Co which has only one peak in its TL(i. e., only one kind of luminescent center and only one kind of traps), and the experimental value of sigma/sigma0 = 0.005, the authors use thermo-luminescence kinetics models and some mathematic tools to exactly estimate the ratio sigma0(n0)/sigma(nu) and the trap depth epsilon simultaneously from the glow curve. The authors found that sigma0(n0)/sigma(nu) = -2.6 and epsilon = 0.86 eV.