The explanation of barrier height inhomogeneities in Au/n-Si Schottky barrier diodes with organic thin interfacial layer

The forward bias current-voltage ( I - V ) characteristics of Au/n-Si Schottky barrier diodes (SBDs) with Zn doped poly(vinyl alcohol) (PVA:Zn) interfacial layer have been investigated in the wide temperature range of 80-400 K. The conventional Richardson plot of the ln ( I o / T 2 ) versus q / k T has two linear regions: the first region (200-400 K) and the second region (80-170 K). The values of activation energy ( E a ) and Richardson constant ( A ∗ ) were obtained from this plot and especially the values of A ∗ are much lower than the known theoretical value for n-type Si. Also the value of E a is almost equal to the half of the band gap energy of Si. Therefore, the Φ ap versus q / 2 k T plot was drawn to obtain the evidence of a Gaussian distribution (GD) of barrier heights (BHs) and it shows two linear region similar to ln ( I o ) / T 2 versus q / k T plot. The analysis of I - V data based on thermionic emission of the Au/PVA:Zn/n-Si SBDs has revealed the existence of double GD with mean BH values ( Φ ¯ B 0 ) of 1.06 eV and 0.86 eV with standard deviation ( σ ) of 0.110 eV and 0.087 V, respectively. Thus, we modified ln ( I o / T 2 ) − ( q σ ) 2 / 2 ( k T ) 2 versus q / k T plot for two temperature regions (200-400 K and 80-170 K) and it gives renewed mean BHs Φ ¯ B 0 values as 1.06 eV and 0.85 eV with Richardson constant ( A ∗ ) values 121 A / cm 2 K 2 and 80.4 A / cm 2 K 2 , respectively. This obtained value of A ∗ = 121 A / cm 2 K 2 is very close to the known theoretical value of 120 A / cm 2 K 2 for n-type Si.