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/T²) versus q/kT 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/2kT 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)/T² versus q/kT 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_B0) 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/T²)-(qσ)²/2(kT)² versus q/kT plot for two temperature regions (200–400 K and 80–170 K) and it gives renewed mean BHs Φ_B0 values as 1.06 eV and 0.85 eV with Richardson constant (A^*) values 121- - 002;A/cm² K² and 80.4 A/cm² K², respectively. This obtained value of A^*=121 A/cm² K² is very close to the known theoretical value of 120 A/cm² K² for n-type Si.