The primary purpose of this thesis is to investigate the transport properties of Sb_1-xSi_x, Zn_x(SiO₂)_1-x and Ag_x(PrBa₂Cu₃O₇)_1-x thin films. Four kinds of physical properties are studied, namely; resistivity, Hall effect, magnetoresistance and thermopower. Our results provide the backdrop in our discussion of the transport properties of these materials near a metal-insulator transition. _{1-x x x 2 1-x}...[ Read more ]

The primary purpose of this thesis is to investigate the transport properties of Sb_1-xSi_x, Zn_x(SiO₂)_1-x and Ag_x(PrBa₂Cu₃O₇)_1-x thin films. Four kinds of physical properties are studied, namely; resistivity, Hall effect, magnetoresistance and thermopower. Our results provide the backdrop in our discussion of the transport properties of these materials near a metal-insulator transition.

First, we report that the semimetal-semiconductor transition of Sb_1-xSi_x is due to a transition in microstructure from a [003] texture polycrystalline Sb for x=0 to non-textured structure, and finally to amorphous. Second, we present the physical properties of Zn_x(SiO₂)_1-x film which can not be fully explained with classical percolation theory. In this system, both the Hall coefficient and the magnetoresistance reach their peaks at quantum percolation threshold. Third, for our Ag_x(PrBa₂Cu₃O₇)_1-x thin film, we compare our resistivity measurement to previous studies on bulk samples. The percolation threshold x_c=0.336 is found to be significantly higher than that in the bulk sample. In addition, a different t-exponent (~1.0) with respect to bulk samples is observed. The Hall effect of samples with various Ag volume fraction strictly obey the scaling law predicted by classical percolation theory. The magnitude of enhancement of Hall coefficient and the scaling exponent of the Hall coefficient are found to be consistent with the classical percolation theory.