[en] This thesis describes the background, motivation and work carried out towards this PhD programme entitled 'Crystalline Silicon Thin Film Growth by ECR Plasma CVD for Solar Cells'. The fundamental principles of silicon solar cells are introduced with a review of silicon thin film and bulk solar cells. The development and prospects for thin film silicon solar cells are described. Some results of a modelling study on thin film single crystalline solar cells are given which has been carried out using a commercially available solar cell simulation package (PC-1D). This is followed by a description of thin film deposition techniques. These include Chemical Vapour Deposition (CVD) and Plasma-Assisted CVD (PACVD). The basic theory and technology of the emerging technique of Electron Cyclotron Resonance (ECR) PACVD, which was used in this research, are introduced and the potential advantages summarised. Some of the basic methods of material and cell characterisation are briefly described, together with the work carried out in this research. The growth by ECR PACVD at temperatures < 700 deg. C of undoped, n-type and p-type crystalline silicon films is discussed in detail. The influence of process parameters such as growth temperature, silane to hydrogen gas ratio, microwave power and gas pressure on film properties, for films grown on silicon and a variety of metal layers, was systematically investigated and is described. The transition from microcrystalline to epitaxial growth was studied. N-type and p-type epitaxial growth was demonstrated at temperatures of ∼470 deg. C and ∼680 deg. C, respectively. Also described is silicon nitride growth at low temperatures (230-500 deg. C) by ECR PACVD. The relations between process parameters (e.g. temperature and silane to nitrogen gas ratio) and film index, growth rate and composition were investigated and are outlined. The application of these films as antireflection coatings (ARC) for thin solar cells is demonstrated. These cells were fabricated on ∼ 15μm thick, p-type base layers epitaxially grown on (100) p+ substrates by conventional CVD. Crystalline, n+ emitter layers were then formed by thermal diffusion of phosphorus or by the ECR PACVD process with phosphine as the doping gas. A description of cell performance as a function of emitter doping and microstructure is given. A conversion efficiency of up to 12.99% was achieved for the diffused emitter structures under 100 mW/cm² illumination. The best efficiency in the ECR grown structures was 13.76% using an epitaxial emitter. Cell performance was analysed in detail and the factors controlling performance identified by fitting self-consistently the fight and dark current-voltage and spectral response data using PC-1D. Finally, the conclusions for this research and suggestions for further work are outlined. (author)

[en] Highlights: • Lager increases in the emission have been achieved by doping Y³⁺ in Li₂CaSiO₄:Eu²⁺. • The enhancement mechanism is due to the increase number of Eu²⁺ with Y³⁺ doping. • Li₂CaSiO₄:Eu²⁺,Y³⁺ is useful for phosphor converted white LEDs and display devices. • Li₂CaSiO₄:Eu²⁺,Y³⁺has higher emission intensity than BAM upon 375 nm excitation. - Abstract: Y³⁺ doped Li₂CaSiO₄:Eu²⁺ phosphors were synthesized by the solid state reaction method. Lager increases in the emission have been achieved by doping Y³⁺ in the host. Upon 375 nm excitation, the present synthesized phosphors have higher emission intensity than that of the commercial blue phosphor, BaMgAl₁₀O₁₇:Eu²⁺. The doping effects of Y³⁺ were discussed systematically based on the analysis of structure, morphology, element, and spectroscopic properties. XRD patterns and EDS spectrum revealed that the samples maintained Li₂CaSiO₄ phase after doping Eu²⁺ and Y³⁺. SEM images showed the morphology and particle size of all phosphors were similar. DRS showed doping Y³⁺ could enhance the absorption of Li₂CaSiO₄:Eu²⁺. Finally, the enhancement mechanism was studied in detail. It was also observed that the emission of Li₂CaSiO₄:Eu²⁺ could also be enhanced by doping other rare earth ions RE³⁺ (RE = Dy, Er, Sm, Tm, Tb, and Yb), which could confirm the mechanism. These results provided a useful basis for further improving the luminescence performance of silicate phosphors

[en] Objective: To investigate the effect of low molecular weight heparin (LMWH) treatment on TNF-α expression in rat models of nephrotic syndrome (NS). Methods: Fourty-eight rat models of nephrotic syndrome (proteinuria over 100 mg/d) were successfully prepared with i.v. adriamycin. After two weeks, half of the models (n=24) were treated with intrapenitoneal LMWH (200u/kg/d). Animals were sacrificed in the two groups of models at the end of 2nd, 3rd and 4th week. The 24h urinary protein, ser- tun albumin and TNF-α levels were measured in these animals. Results: In the nephrotic syndrome models, the serum TNF-α levels were significantly higher than those in the 18 control rats. The levels were positively correlated with the amount of 24h proteinuria (P<0.01). In the models treated with LMWH, the serum TNF-α levels decreased, 24h proteinuria decreased with increased serum albumin (vs the corresponding values in those models without LMWH treatment, P<0.05 or P<0.01). Conclusion: LMWH treat- merit could decrease the serum TNF-α levels in rat models of nephrotic syndrome, which might be one of the nephro-protective mechanisms of LMWH. (authors)

[en] We present multi-color CCD photometry of the neglected contact binary XZ Leo. Completely covered VRI band light curves and four times of minimum light were obtained. Combining the photometric and previously published radial-velocity data, a revised photometric analysis was carried out for the binary system by applying the Wilson–Devinney code. With a hot spot placed on the massive primary component near the neck region of the common envelope, the light curves were satisfactorily modeled. The photometric solution combined with the radial-velocity solution reveals that XZ Leo is an A-type contact binary with a degree of contact of 24(±1)%. The absolute parameters of the components were determined to be M₁ = 1.74(±0.06)M_⊙, M₂ = 0.61(±0.02)M_⊙, R₁ = 1.69(±0.01)R_⊙, R₂ = 1.07(±0.01)R_⊙, L₁ = 6.73(±0.08) L_⊙, and L₂ = 2.40(±0.04)L_⊙. Based on all the available data, the long-term orbital period behavior of the system was investigated. It indicates that the binary system was undergoing a continuous orbital period increase in the past three decades with a rate of $dP/dt=+6.12\times <!--\; ??\; -->{10}^{-<!--\; ???\; -->8}\mathrm{d}\mathrm{a}\mathrm{y}\mathrm{s}{\mathrm{y}\mathrm{r}}^{-<!--\; ???\; -->1}$, which suggests a probable mass transfer from the secondary to the primary component at a rate of $dM/dt=3.92\times <!--\; ??\; -->{10}^{-<!--\; ???\; -->8}{M}_{\odot <!--\; ???\; -->}{\mathrm{y}\mathrm{r}}^{-<!--\; ???\; -->1}$. The binary system is expected to evolve into the broken-contact stage in $1.56\times <!--\; ??\; -->{10}^6$ years. This could be evidence supporting the thermal relaxation oscillation theory.

[en] Symbolically investigated in this paper is the extended Lotka-Volterra (ELV) equation, which can govern the kinetics of the discrete peaks of the weak Langmuir turbulence in plasmas without the linear damping and random noise. Binary Bell polynomials are applied to the bilinearization of the discrete system. Bilinear Baecklund transformation of the ELV equation is constructed. N-soliton solution in terms of the extended Casorati determinant is also presented and verified. Propagation and interaction behaviors of the Langmuir turbulence are analyzed. It is demonstrated that the number of the interacting Langmuir waves can influence the soliton velocity and amplitude as well as the collision phase shift. Graphic illustrations of the solitonic collisions show that the repulsion effects and nonlinear interactions are also associated with the number of the interacting Langmuir waves.