Optical absorption and Hall effect in (220) and (400) oriented polycrystalline silicon films

Carrier transport properties were investigated for polycrystalline silicon (poly-Si:H:F) films fabricated at 300 degrees C by 100 MHz plasma enhanced chemical vapor deposition from gaseous mixture of SiF4 and H-2. Analysis of free carrier optical absorption (FCA) revealed that 1 mu m thick (400) ori ented phosphorus-doped poly-Si:H:F films with a carrier concentration of 5x 10(19) cm(-3) had the average electron mobility in crystalline grains at 40 cm(2)/V s, while the electron mobility of the (220) oriented phosphorus-do ped poly-Si:H:F films was only 12 cm(2)/V s. These results indicated that ( 400) oriented poly-Si:H:F films had excellent quality crystalline grains. A nalyses of the FCA combined with Hall effect current measurements revealed that the electrical conductivity at grain boundaries of top doped films inc reased as the underlying film thickness increased from 0 to 280 nm for (400 ) oriented phosphorus-doped/undoped double layered samples, but grain bound aries still acted as large resistive regions limiting the effective conduct ivity. (C) 2000 American Institute of Physics. [S0021- 8979(00)03118-2].