Carrier transport, structure and orientation in polycrystalline silicon on glass

Polycrystalline silicon films exhibiting (220) and (400) preferential orientation in X-ray diffraction (XRD) were grown on glass substrate from gaseous mixture of SiF4 and H-2, respectively, using a remote type plasma enhanced chemical vapor deposition (PECVD). In particular, the grains of (400) oriented texture showed smooth surface resulting from its highly selective sticking of deposition precursor on a certain site of (100) surface. Hall mobility at room temperature of (220) and (400) oriented films rose by 12 and 7 cm(2)/Vs, respectively, with increasing the grain size and decreasing the structure fluctuation. In addition, the Hall mobility observed in these films is characterized by a thermally activated process given by the equation, mu = mu(0)exp(-E mu/kT) where mu(0), E mu, k and T are the extended mobility, activation energy, Boltzmann constant and temperature, respectively. The mu(0) increased with increasing the grain size up to 40 cm(2)/Vs at the grain size of 250 nm diameter, whereas E mu was kept constant at around 35 meV being independent of grain size, where a part of the free electrons is considered to be localized in the shallow traps being in 'thermal contact' with the conduction band. (C) 1999 Elsevier Science S.A. All rights reserved.