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Abstract: Hydrogenation by plasma is a low cost and efficient method to improve the photovoltaic properties of multicrystalline silicon. The role of plasma parameters on the efficiency of hydrogenation was studied using secondary ion mass spectrometry (SIMS), hydrogen effusion, electrochemical impedance spectroscopy and electron beam induced current (EBIC). The experimental results showed a deuterium concentration of 1020 atomscm−3 could be reached in the sample after a 15-min treatment. Optimal treatment time depends on temperature and leads to maximum electrical conductivity and minority carrier diffusion length. The results confirm the reduction of defects densities and potential barriers associated with grain boundaries. [Copyright &y& Elsevier]

The photovoltaic properties of polycrystalline silicon depend on the crystallinity and the purity of the material. The hydrogenation of silicon leads to a passivation of crystalline defects and active impurities. In this paper, we demonstrate that the chemical properties of the plasma can be controlled in order to purify and introduce hydrogen in silicon in order to produce a material with photovoltaic properties even if the density of dislocations is high. The comparison of two plasma processes shows that the hydrogenation of the silicon in liquid state produces strong bonds between hydrogen and silicon atoms. This is due to the excited state of hydrogen (n=8) generated at a temperature close to 11000 K in the inductive coil area of the RF plasma. Experimental measurements of the plasma properties (electronic density, electronic temperature) are in agreement with the calculations resulting from the modeling. [ABSTRACT FROM AUTHOR]

The hydrogenation of silicon material proves great advantages concerning its photovoltaic properties and secure a key for the elimination of crystalline defects during the basaltic growth of the crystal. In our process, silicon particles are hydrogenated in the thermal plasma torch at atmospheric pressure. So, the aim of this work is to characterise the physical properties of the plasma flow in order to understand the interaction appearing between particles and hydrogenated plasma flow during the treatment. Highly excited states of atomic hydrogen, responsible of the silicon hydrogenation, have been detected in the plasma. These atomic hydrogen lines have been used to determine the electronic density on the plasma axis. Electronic temperature of different plasma mixture have been obtained by the Boltzmann plot method. [ABSTRACT FROM AUTHOR]