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Cu(In,Ga)Se2 (CIGSe)-based solar cells are promising candidates for efficient sunlight harvesting. However, their complex composition and microstructure can change under operation conditions, for instance heating from sun light illumination can lead to a degradation in performance. Here, we investigate the thermally-induced degradation processes in a set of CIGSe-based solar cells that were annealed at temperatures between 150C and 300C. Using correlative atom probe tomography (APT)/transmission electron microscope (TEM), we found that the buffer-absorber interface is not sharp but consists of an interfacial zone (2 - 6.5 nm wide) where a gradient of constituent elements belonging to the CdS buffer and CIGSe absorber appears. An enhanced short-range Cd in-diffusion inside the CIGSe was observed whenever a low Ga/(Ga+In) ratio occurred at the interface. This might indicate the presence of Ga vacancies as a channeling defect for Cd in-diffusion inside the CIGSe layer leading to a buried pn-homojunction. We evidence that a considerable amount of Cd is found inside the CIGSe layer at annealing temperatures higher than 150C. Further investigations of the elemental redistribution inside the CIGSe layer combined with C-V measurements support the formation of CdCu donor like defects deep inside the p-type CIGSe which lead to a strong compensation of the CIGSe layer and hence to strong deterioration of cell efficiency at annealing temperatures higher than 200C. Hence, understanding the degradation processes in Cu(In,Ga)Se2 (CIGSe)-based solar cells opens new opportunities for further improvement of the long-term device performance.

Evolution of winding strings in spacetimes with cycles whose proper lengths depend on time is examined. It was established earlier that extended objects wrapping the shrinking dimension in compactified Milne spacetime enjoy classically nonsingular evolution. Extensions of this observation to other spacetimes are discussed.

The velocity dependence of energy and momentum is studied. It is shown that in the case of STR in the space-time of only one spatial dimension the standard energy and momentum definition can be naturally modified without lost of local Lorenz invariance, conservation rules and additivity for multiparticle system. One parameter family of energies and momenta is constructed and it is shown that within natural conditions there is no further freedom. Choosing proper family parameter one can obtain energy and momentum increasing with velocity faster or slower in comparison with the standard case, but almost coinciding with them in the wide velocity region.

Special Relativity (SR) kinematics is derived from very intuitive assumptions. Contrary to standard Einstein's derivation, no light signal is used in the construction nor it is assumed to exist. Instead we postulate the existence of two equivalence classes of physical objects: proportional clocks and proportional rulers. Simple considerations lead to Lorentz kinematics as one of three generic cases. The Lorentz case is characterized by the maximal relative speed of physical objects. The two others are the Galilean and the Euclidean cases., Comment: 6 pages, 2 figures

The paper is devoted to the description of the reparametrization - invariant dynamics of general relativity obtained by resolving constraints and constructing equivalent unconstrained systems. The constraint-shell action reveals the "field nature" of the geometric time in general relativity. The time measured by the watch of an observer coincides with one of field variables, but not with the reparametrization-noninvariant coordinate evolution parameter. We give new solution of such problem, as the derivation of the path integral representation of the causal Green functions in the Hamiltonian scheme of general relativity., Comment: 12 pages, Latex file, no figures, talk presented at the XXIII International Colloquium on Group Theoretical Methods in Physics, Dubna, Russia, 30 July - 5 August 2000

The Weyl-Weinberg-Salam model is presented. It is based on the local conformal gauge symmetry. The model identifies the Higgs scalar field in SM with the Penrose-Chernikov-Tagirov scalar field of the conformal theory of gravity. Higgs mechanism for generation of particle masses is replaced by the originated in Weyl's ideas conformal gauge scale fixing. Scalar field is no longer a dynamical field of the model and does not lead to quantum particle-like excitations that could be observed in HE experiments. Cosmological constant is naturally generated by the scalar quadric term. The model admits Weyl vector bosons that can mix with photon and weak bosons., Comment: 10 pages, latex, aipproc.sty, no figures, talk given at the International Conference Particles, Fields and Gravitation, Lodz, April 1998

The old Weyl's idea of scale recalibration freedom and the Infeld and van der Waerden (IW) ideas concerning geometrical interpretation of the natural spinor phase gauge symmetry are discussed in the context of moderm models of fundamental particle interactions. It is argued that IW gauge symmetry can be naturaly identified with U(1) symmetry of Weinberg-Salam model. It is also argued that there are no serious reasons to reject Weyl's gauge theory from the considerations. Its inclusion enriches the original Weinberg-Salam theory and leads to predictions of new phenomena that do not contradict experiments., Comment: 11 pages, latex, no figures; invited talk given at the international workshop "Macroscopic Electrodynamics II", Krakow, November 97; proceedings to be published in Turkish J. of Physics

In 1992 Professor Ryszard R\c{a}czka started to work on formulation of a version of the Standard Model conformally coupled with gravity. Being his student I had got the honour to participate in those researches. The conformally invariant Higgs-Free Model was the result of our investigations. Ryszard R\c{a}czka passed away on 26 August 1996. I present here a short memorial survey of our results., Comment: Dedicated to the memory of Ryszard Raczka, 6 pages, latex, no figures

If the "Higgs mass" is not the physical mass of a real particle but rather an effective ultraviolet cutoff then a process energy dependence of this cutoff must be admitted. Precision data from at least two energy scale experimental points are necessary to test this hypothesis. The first set of precision data is provided by the $Z$-boson peak experiments. We argue that the second set can be given by 10-20GeV $e^+e^-$ colliders. We put attention to the special role of tau polarization experiments that can be sensitive to the "Higgs mass" for a sample of $\sim10^8$ produced tau pairs. We argue that such a study may be regarded as a negative selfconsistency test of the Standard Model and of most of its extensions., Comment: 8 pages, latex, 3x2 .ps figures

The predictions for electroweak observables following from Higgs-Free Model for Fundamental Interactions are derived. It is shown that these predictions are close to the Standard Model predictions and they are in a surprising agreement with the experimental data. The analysis of electroweak observables at low and high energy suggests that the Higgs mass $m_H$ is just the ultraviolet cutoff which increases if the process energy scale increases. We propose several experimental tests which can discriminate between the Standard and the Higgs-Free Models., Comment: 1+12 pages, uuencoded, compressed p2.ps file. Revised version: new data included, improved presentation

We show that the local conformal group $C$ is a natural symmetry group of strong, electroweak and gravitational interactions. A model for these interactions invariant under the local symmetry group $G=SU(3)\times SU(2)_{L}\times U(1)\times C$ is postulated. It contains all Standard Model and gravitational fields, however the Higgs mass term $\mu^2\Phi^{\dagger}\Phi$ is forbidden. Using the unitary gauge and the conformal scale fixing conditions we can eliminate all four real components of the Higgs field in this model. In spite of that the tree level masses of vector mesons, leptons and quarks are automatically generated and they are given by the same formulas as in the conventional Standard Model. The gravitational sector of the model is also analyzed and it is shown that the model admits in the classical limit the Einsteinian form of gravitational interactions. We propose several experimental tests which can discriminate between the Higgs-Free and the Standard Models., Comment: 1+23 pages, uuencoded, compressed p1.ps file. Revised version: new data included, improved presentation

A model for strong, electroweak and gravitational interactions based on the local symmetry group $G=SU(3)\times SU(2)_{L}\times U(1)\times C$ where $C$ is the local conformal symmetry group is proposed. The natural minimal $G$-invariant form of total lagrangian is postulated. It contains all Standard Model fields and the gravitational interaction, however the Higgs mass term $\mu^2\Phi^{\dagger}\Phi$ is forbidden. Using the unitary gauge and the conformal scale fixing conditions we can eliminate all four real components of the Higgs field in this model. In spite of that the tree level masses of vector mesons, leptons and quarks are automatically generated and are given by the same formulas as in the conventional Standard Model. In this manner one gets the mass generation without the mechanism of spontaneous symmetry breaking. We calculated in this model the predictions for a series of electroweak observables such as $m_{W_{\pm}}/m_Z$, $sin^2\theta_W^{eff}$, Z-boson widths, $A^l_{FB}$, etc, and we show that they are in agreement with experimental data. The gravitational sector of the model is also analyzed and it is shown that the model admits in the classical limit the Einsteinian form of gravitational interactions., Comment: 29 pages, 5 figures postscript

A Higgsless model for strong, electro-weak and gravitational interactions is proposed. This model is based on the local symmetry group SU(3)xSU(2)xU(1)xC where C is the local conformal symmetry group. The natural minimal conformally invariant form of total lagrangian is postulated. It contains all Standard Model fields and gravitational interaction. Using the unitary gauge and the conformal scale fixing conditions we can eliminate all four real components of the Higgs doublet in this model. However the masses of vector mesons, leptons and quarks are automatically generated and are given by the same formulas as in the conventional Standard Model. The gravitational sector is analyzed and it is shown that the model admits in the classical limit the Einsteinian form of gravitational interactions. No figures., Comment: 25 pages, preprint

We call attention to the fact that the gauge symmetry $SU(3)\times SU(2)_{_L}\times U(1)$ of the Standard Model can be easily and naturally extended by the local conformal symmetry connected with the possibility of choosing the local length scale. Restricting the admissible interactions to the lowest order conformal invariant interactions one gets the unique form of total lagrangian. It contains all Standard Model fields and gravitational interaction. Using the unitary and the conformal gauge conditions we can eliminate all four real components of the Higgs doublet in this model. However the masses of vector mesons, leptons and quarks are automatically generated and are given by the same formulas as in the conventional Standard Model. In this manner one gets the mass generation without the mechanism of spontaneous symmetry breaking and without the remaining real dynamical Higgs field., Comment: 9p, ILAS 2/94, 20kb, Latex