Impact of Hydrogen Passivation on Electrical Properties of Polysilicon Thin Films

The effect of hydrogen passivation and heat treatments on the electronic activity at grain boundaries in thin films of polysilicon deposited by LP-CVD (Low Pressure Chemical Vapor Deposition) has been studied. The results obtained have shown that the introduction of hydrogen into polysilicon thin films doped with arsenic ions increases the concentration of free carriers, reduces the resistivity and lowers the density of trap states at the grain boundaries. Free carriers concentration improved by almost 10% at the annealing temperature of 1000 °C. In addition, it was found that the effect of hydrogen is much more pronounced for low temperature heat treatment before doping compared to the effect at the higher temperature. Moreover, the increase in free carrier concentration and the decrease in resistivity of polysilicon thin films with the increase in the annealing temperature has been observed.