Electrical Conductivity of Composite Materials Based on Fine-Particle Silicon near the Metal–Insulator Transition

Si/SiO2 composites containing 17, 19, and 21 wt % crystalline B-doped Si particles (near the insulator–metal transition) are studied by impedance spectroscopy. The results indicate that, at low frequencies, the nonlinear variation of the real part of electrical conductivity, Re σ, with applied dc voltage V for the composite containing 17 wt % Si (dielectric properties) is due to the current being limited by the space charge buildup at traps in the silica layers between Si particles. At high frequencies, the nonlinear Re σ(V) behavior is due to tunneling through the contacts between the particles.