Investigation of Dielectric Properties of Ni/n-TiO2/p-Si/Al Heterojunction in Wide Range of Temperature and Voltage

Abstract

In the present study we have investigated the dielectric properties such as dielectric constant (ℇ′), dielectric loss (ℇ′′), real part of electrical modulus (M′), imaginary part of electric modulus (M′′) and AC electrical conductivity, (σac) in wide range of applied voltage, temperature and frequency for Ni/nTiO2/p-Si/Al heterojunction. A nanocrystalline TiO2 layer was grown on p-type boron doped silicon in oxygen-controlled environment using optimized KrF excimer laser. Ohmic contact of pure nickel and aluminum metals was made on TiO2 and silicon respectively, with thermal coating system. The characteristics obtained with the help of conductance-voltage and capacitance-voltage measurements also known as impedance/admittance spectroscopy. The studied parameters are found to be very sensitive to frequency, temperature and voltage. The restructuring and reordering of interface state density due to temperature variations and interfacial polarizations due to frequency variations collectively result the observed changes in the ℇ and ℇ . With an increase in frequency AC conductivity and electrical modulus also increases. The relaxation mechanism can be observed in the complex electrical modulus analysis. The thermally activated conduction process was indicated by the frequency dependent AC conductivity at different temperatures. Using power law, the AC conductivity was analyzed and found to increase with temperature, applied voltage.