Effects of plasma parameters on passivation of polycrystalline silicon in inductive low pressure hydrogen plasma.

Passivation of crystallographic defects by hydrogen is known to improve the transport properties and to enhance the photovoltaic yield of polycrystalline silicone (poly Si). However, it has been demonstrated that the efficiency of hydrogenation depends on the process used. The treatment of poly Si was performed in an inductive low pressure hydrogen plasma reactor. The aim of this work is to elucidate the relation between the plasma characteristics and the efficiency of hydrogen passivation on a poly Si surface. Optical emission spectroscopy permitted to determine the main excited states of monatomic hydrogen and molecular hydrogen in the plasma. The excitation temperature measured by Boltzmann's method ranged between 4500 and 8000K depending on the plasma gas composition, pressure and applied power. The effects of these parameters on the efficiency of hydrogenation were studied by SIMS, EBIC, and hydrogen effusion.