The interfacial interaction between phosphorus-doped amorphous silicon hydrogen alloy((n+)a-Si:H)and thermal evaporated Al-1&percent;Si layer after furnace annealing in the temperature range from 150 to 250 °C has been investigated in detail. The scanning electron microscope photographs show that many dendrites were formed on the original(n+)a-Si:Hsurface at annealing temperature higher than 170 °C. Raman spectroscopy and transmission electron diffraction show that the original(n+)a-Si:Hfilm has been converted to polycrystalline Si with the crystalline Si dendrites on top. The drastic increase (∼4orders of magnitude) of electrical conductivity of the 200 °C annealed(n+)a-Si:Hfilms with the Al-1&percent;Si removed is caused by the formation of polycrystalline silicon percolation channel in the background area between dendrites. Auger spectroscopy also provides evidence that no aluminum is incorporated into the converted film during silicon recrystallization and thus no SiAl alloy is formed. ©1997 American Institute of Physics.