Diode-to-diode variation in dielectric parameters of identically prepared metal-ferroelectric-semiconductor structures

In this research, a total number of 58 diodes were fabricated in the form of Al/Bi4Ti3O12/p-Si structure and the voltage dependence of the real and imaginary parts of the complex dielectric constant (epsilon' and epsilon) and complex electric modulus (M' and M'') and ac electrical conductivity (sigma(ac)) of these diodes were investigated. It was also aimed to determine whether or not these parameters change from one sample to another and what kind of distribution exists for the identically fabricated samples. Mentioned parameters (e', e'', M', M'' and sac) were calculated using the capacitance and conductance data that were measured between -4 V and 4 V at 500 kHz at room temperature. Experimental results show that all of these parameters are strong functions of applied bias voltage especially in the depletion and accumulation regions. These changes are results of the restructuring and reordering of the surface states and their relaxation time under external electric field. Besides, it was found that there is diode-to-diode variation among the values of dielectric parameters which revealed double Gaussian distribution for the total 58 diodes. Thus, the results confirmed that investigating these parameters only for a single sample at a single bias voltage value cannot supply enough information on the dielectric properties and electric modulus. Therefore these parameters must be calculated in the wide range of bias voltage even for the identically prepared samples on the same semiconductor wafer. (C) 2017 Elsevier B.V. All rights reserved.