Dielectric properties, electrical modulus and current transport mechanisms of Au/ZnO/n-Si structures

Abstract

Au/ZnO/n-Si (MIS) structures were fabricated by using the RF sputtering method and their complex dielectric constant (ε*=ε’-jε’’), electric modulus (M*=M′+ jM’’) and electrical conductivity (σ = σdc+σac) values were investigated as a function of frequency (0.7 kHz-1 MHz) and voltage (−6 – (+6 V)) by capacitance-voltage (C-V) and conductance-voltage (G/ω-V) measurements to get more information on the conduction mechanisms and formation of barrier height between Au and n-Si. The lnσ-Lnf plots have two different regions corresponding to low-intermediate and high frequencies. Such behavior of lnσ−lnf plots shows that the existence of two different conduction mechanisms (CMs) at low-intermediate and high frequencies. Moreover, the reverse bias saturation current (Io), ideality factor (n), barrier height (ΦBo) were determined from the forward bias I-V data and they were found as a strong function of temperature. The value of n especially at low temperature is considerably higher than unity. The values of Φ̅B0 and standard deviation(σs) were found from the intercept and slope of ΦBo-q/2kT plots as 0.551 eV and 0.075 V for the region I (80–220 K) and 1.126 eV and 0.053 V for the region II (220–400 K), respectively. The values of Φ̅Bo and effective Richardson constant (A*) were found from slope and intercept of activation energy plots as 0.564 eV and 101.084 Acm−2 K−2 for the region I and 1.136 eV and 41.87 Acm−2 K−2 for the region II, respectively. These results confirm that the current-voltage-temperature (I-V-T) characteristics of the fabricated Au/ZnO/n-Si SBDs can satisfactorily be explained on the basis of TE theory with double GD of the BHs.