Optical emission spectroscopic investigation of hydrogen plasma used for modification of electrical properties of multi-crystalline silicon

摘要

Results of the treatment of multi-crystalline silicon with low-pressure inductive plasma are presented. Plasma treatment was found to increase silicon electrical conductivity to a greater value relative to its initial state; the time to reach this maximum was found to depend strongly on temperature between 120 and 400 degrees C. An effect of plasma parameters on collection efficiency and diffusion length was observed by EBIC measurements. An actinometry method based on optical emission spectroscopy measurements was used to determine the molar fraction of monatomic hydrogen produced in plasma in the range between 5% and 8% during the treatment. The excitation temperature calculated by Boltzmann's method ranged between 4500 and 8000K depending on the plasma gas composition, the pressure and the applied power. A model was developed using the CHEMKIN III (R) software to compute the role of operational parameters in hydrogen-silicon interactions. The aim of this work is to elucidate the relation between the plasma characteristics and the efficiency of hydrogen passivation on multi-crystalline silicon.