Current-transport mechanisms in gold/polypyrrole/n-silicon Schottky barrier diodes in the temperature range of 110―360 K

In this study, Au/polypyrrole/n-Si metal-polymer-semiconductor (MPS) Schottky barrier diode (SBD) was fabricated by using a spin coating system for formation of polypyrrole (PPy) organic layer and a thermal evaporation system for deposition of metal contacts. The forward bias current-voltage-temperature (I-V-T) characteristics of the diode were investigated in the temperature range of 110-360 K. The some main electrical parameters such as the zero-bias barrier height ( Phi sub(bo)), ideality factor (n), and effective barrier height ( Phi sub(bef)) were found as function temperature. The experimental results show that the I-V-T characteristics have a non-linear behavior especially due to the effect of series resistance (R sub(s)) and interfacial polymer layer by resulting a higher n value of 3.09 larger than unity (n>1). While the value of Phi sub(bo) increases, n decreases with increasing temperature and such changes in Phi sub(bo) and n with temperature was attributed to the presence of saddle point or pinch-off at around mean BH value ( ) at M/S interface. The value of Richardson constant (A super(*)) was obtained from the slope of conventional Richardson plot, ln(I sub(0)/T super(2)) vs (q/kT) as 1.39510 super(-8) A/cm super(2) K super(2) which is much lower than the known theoretical value of 112 A/cm super(2) K super(2) for n-Si. The and standard deviation ( sigma sub(0)) were obtained from the intercept and slope of Phi sub(bo) vs q/kT plot as 1.146 eV and 0.13 V. Thus, the and effective value of A super(*) were obtained as 1.078 eV and 113.03 A/cm super(2) K super(2) from the modified Richardson plot. The obtained experimental value of A super(*) is in a good agreement with the theoretical value of 112 A/cm super(2) K super(2) for n-Si. As a result, current transport mechanism (CTM) in MPS type SBD can be successfully explained on the basis of thermionic emission (TE) theory with Gaussian distribution (GD) of barrier heights (BHs) around .