The investigation of temperature and radiation dependent electrical characteristics of Au/PVA:Zn/n-Si (MPS) schottky barrier diodes

The forward and reverse bias current-voltage (I-V), capacitance-voltage (C-V) and conductance-voltage (G/ ? -V) characteristics of Au/n-Si Schottky barrier diodes (SBDs) with Zinc acetate [Zn(CH3COO)2.2H2O] doped poly(vinyl alcohol) (PVA:Zn) interfacial layer have been investigated in the wide temperature range of 80-400 K. The crossing of the experimental forward bias semi-logarithmic ln I-V plots is rather unexpected and seems to be in contradiction with thermionic concept of current transport. The abnormal behavior of current-voltage characteristics of SBD has been attributed to spatial variation of barrier height. The analysis of I-V data based on thermionic emission (TE) of the Au/PVA:Zn/n-Si SBDs has revealed the existence of double Gaussian distribution (GD) with mean barrier height (BH) values ( ) of 1,06 and 0,86 eV with standard deviation (?) of 0,110 and 0,087 V, respectively. Thus, we modified ln(Io/T2)-(q ? )2/2(kT)2 vs q/kT plot for two temperature regions (200-400 K and 80-170 K) and it gives renewed mean barrier heights values as 1,06 and 0,85 eV with Richardson constant (A*) values 121 and 80,4 A/cm2K2, respectively. This obtained value of A*=121 A/cm2K2 is very close to the known theoretical value of 120 A/cm2K2 for n-type Si. Our experimental results show that both series resistance (Rs) and interface states (Nss) were strongly functional with temperature. It was observed that C-V and G/ ? -V plots exhibited anomalous peak at forward bias because of Rs and thermal restructuring and reordering of Nss. The density of Nss depending on temperature was determined both by I-V data as a function of energy and Hill-Coleman method using C-V and G/ ? -V characteristics. In addition, to see gamma-ray irradiation effect on electrical characteristics of Au/PVA:Zn/n-Si SBD, the sample was exposed to 60Co ? -ray source at 20 kGy. It was seen that the barrier height and ideality factor calculated from I-V characteristics decreased after the applied radiation, while the saturation current and series resistance values increased. It was also seen that the carrier concentration, the capacitance and conductance of device decreased with radiation dose.Key Words : Au/PVA:Zn/n-Si (MPS) structures; Electrical properties; Temperature effect; Double Gaussian distribution(GD) Radiation effect.