Electronic transport studies on Sb_1−x(SiO₂)_xfilms

Abstract

Sb_1-x(SiO₂)_x granular films were prepared by the co-sputtering method with the volume fraction of SiO₂, x, ranging from 0 (i.e. pure Sb) to about 30%. Systematic electronic transport studies, including resistivity, magnetoresistance, Hall effect and Seebeck effect, were carried out against the temperature, magnetic field and volume fraction x of SiO₂. With the gradual increase of the SiO₂ content, the mean grain size of the Sb decreases, and eventually the film becomes amorphous, as illustrated by the changes of the x-ray diffraction patterns. The temperature coefficient of resistivity also changes its sign from positive to negative, indicating a semimetal-semiconductor or insulator transition. Magnetoresistance studies using the weak localization theory revealed that the electron dephasing time follows approximately a T^-2 law. This behaviour indicates that the electron-phonon (e-ph) scattering still dominates the electron dephasing processes in these granular systems with a fair number of SiO₂ inclusions. The Hall coefficient decreases monotonically with temperature and with the volume fraction of SiO₂. The giant Hall effect is absent in these granular films. Finally, an interesting but rather complicated behaviour of the Seebeck coefficient versus temperature was observed when the volume content of the SiO₂ exceeded 18%.