I-V-T analysing an inhomogeneous Au/Poly(4-vinyl phenol)/p-Si structure with a double Gaussian distribution of barrier heights

摘要

In this study, the current-voltage (I-V) characteristics of Au/Poly(4-vinyl phenol)/p-Si structures have been measured over a wide temperature range (100-300 K). These structures have been analyzed according to thermionic emission (TE) theory, as a result of which an abnormal decrease occurred in the zero-bias barrier height (φ_(b0)) and an increase in the ideality factor (n) was observed with temperature decrease and nonlinearity in the activation energy plot. By assuming a Gaussian distribution (GD) of barrier heights of the Au/Poly(4-vinyl phenol)/p-Si structures, barrier inhomogeneities are believed to responsible for this behavior. Evidence is given for the existence of a double GD with mean barrier heights (φ_(b0)) of 1.042 and 0.623 eV, standard deviations of 0.138 and 0.081 V, and ideality factors 2.76 and 7.26, which remain effective in the temperature ranges of 180-300 and 100-160 K, respectively. As aresult, without using the temperature coefficient of the barrier height, the modified ln(I0/T~2) - q~2σ_o~2/2(kT)~2 vs. q/kT plot gives φ_(b0) values and Richardson constants (A*) as 1.036 and 0.623 eV, and 36.20 and 19.99 A/cm~2 K~2, respectively. The effective Richardson constant value of 36.20 A/cm~2 K~2 is very similar to the theoretical value of 32 A/cm~2K~2 for p-Si. Consequently, the temperature dependence of the forward bias I-V characteristics of Au/Poly(4-vinyl phenol)//p-Si (MIS) structure could be attributed to the thermionic emission (TE) mechanism with double GD of the barrier heights.