Hydrogen radical annealing effect on the growth of microcrystalline silicon

We have studied the growth of microcrystalline silicon (μc-Si) and amorphous silicon (a-Si:H) by layer by layer deposition technique, where the deposition and the radical exposure are done alternatively. He or hydrogen plasma exposure gives rise to the etching effect of both μc-Si and a-Si:H even though the etch rate by He plasma is much smaller. The long exposure of hydrogen radical on a-Si:H gives to the formation of μc-Si at low substrate temperature (T_s), whereas the hydrogen content decreases at high T_s. The growth mechanism of the crystalline is proposed on the basis of experimental results.