ELECTRON-MICROSCOPY AND ELECTRON CONDUCTA NCE MEASUREMENTS IN-SITU OFTHE CRYSTALLIZATION OF A-SI FILMS PRODUCED BY SILANE AND DISILANE PYROLYSIS WITH LPDVD (LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION) UNDER HIGH-PURITY CONDITIONS

High purity amorphous silicon layers were deposited by low pressure ch emical vapour deposition (LPCVD) from either silane or disilane gases. During the solid phase crystallisation of the amorphous layers at 580 degrees C, the grain density was followed by electron microscopy and the nucleation rate at that temperature was extracted. Moreover, the v ariation of the grain size of the completly cristallised films as a fu nction of annealing temperature was studied by transmission electron m icroscopy (TEM). The crystalline fraction was monitored by in situ ele ctrical conductance measurements during isothermal annealings. Using t hese two caracterisation methods, we were able to precisely determine the thermodynamic cristallisation parameters for both types of film st udied.