Novel technique to fabricate polycrystalline silicon thin films onglass substrates with controlling grain orientations was developed.Random, (220) or (400) preferential orientations were attained bycontrol of source gas mixing ratio SiF4/Mz2. In this study, a remotetype plasma chemical vapor deposition system was used with gasmixtures of SiF4, H2 and Ar. The randomly oriented films wereobtained under very large mixing ratio SiF4/M2>90/ssccm while the(220) oriented films were obtained under small gas flow rate ratioregion SiF4/H2<60/10sccm. It was found that the (400) preferentialoriented films were obtained at higher SiF4/H2 ratios(SiF4/H2=90/10sccm). The (400) oriented crystallites have excellentcrystalline regularity compared to that of the (220) oriented films,however, their electron mobility is lower than the (220) orientedfilms'. The small Hall mobility of the (400) oriented films isthought to onginate from large orientation fluctuation and lesspassivated dangling bonds at the grain boundaries.
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