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We have investigated CdTe thin film solar cells without activation treatment and with CdCl2activation treatment at temperatures between 370 and 430 C using a constant activation time of25 min. For this purpose, CdS/CdTe layers were deposited by closed-space-sublimation on FTO coated float glass. The solar cells were characterized by measurements of the JV characteristics and quantum efficiencies. In addition, ion polished cross sections of the solar cells were prepared for high-resolution FE-SEM imaging of the microstructure and the simultaneous registration of electron beam induced current (EBIC) signal distribution. By measurement of the EBIC signal distribution, it can be shown that without activation treatment the CdTe grain boundaries itself and grain boundary near regions exhibit no EBIC signal, whereas centres of some singular grains already show a distinct EBIC signal. In contrast, after the chlorine activation treatment, the grain boundary near regions exhibit a significant higher EBIC signal than the centre of the grains. The results can be discussed as a direct evidence for defect passivation of grain boundary near regions by the chlorine activation treatment. At activation temperature of 430 C, additionally, a significant grain growth and agglomeration of the CdS layer can be recognized, which is linked with the formation of voids within the CdS layer and a deterioration of pn junction properties

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Hollow cathode arc discharges have been studied for some decades in basic research and different fields of practical application. Especially in the field of physical vapor deposition (PVD) they are often used for metal evaporation and the generation of plasma. Problematical aspects were found in the high throughput of working gas necessary for stable operation and in the inhomogeneous, locally concentrated ionization efficiency. A promising way out of this dilemma was found in a special arrangement of hollow cathode and annular anode in an axial magnetic field. This configuration allows a drastic reduction of working gas flow without loss of discharge stability. Moreover, with reduction of gas flow a strong increase in ion current density was observed together with a highly expanded volume of plasma plume.