Analysis of temperature dependent current-conduction mechanisms in Au/TiO2/n-4H-SiC (metal/insulator/semiconductor) type Schottky barrier diodes

Abstract

In order to determine the effective current-conduction mechanisms in Au/TiO2/n-4H-SiC (metal-insulator semiconductor) type Schottky barrier diodes (SBDs), their current-voltage (I-V) measurements were carried out in the temperature range of 200-380K. Some electrical parameters, such as ideality factor (n), zero-bias barrier height (BH) (?Bo), series and shunt resistances (Rs, Rsh), were obtained as 5.09, 0.81eV, 37.43 ?, and 435k? at 200K and 2.68, 0.95eV, 5.99 ?, and 73k? at 380K, respectively. The energy density distribution profile of surface states (Nss) was extracted from the forward-bias I-V data by taking into account voltage dependent of the ideality factor (nV), effective BH (?e), and Rs for 200, 300, and 380K. The Ln(I) vs V plots are completely parallel in the intermediate bias voltages, which may be well explained by field emission (FE) mechanism for each temperature. On the other hand, the high value of n cannot be explained with this mechanism. Therefore, to explain the change in BH and n with temperature, ?Bo vs q/2kT plot was drawn to obtain an evidence of a Gaussian distribution (GD) of the BHs and thus the mean value of BH (?? Bo) and standard deviation (?so) values were found from this plot as 1.396eV and 0.176V, respectively. The ??Bo and Richardson constant (A*) values were found as 1.393eV and 145.5A.cm-2 K-2 using modified Ln(Io/T 2)-(q2?s2/2k2T 2) vs q/kT plot, respectively. It is clear that all of the obtained main electrical parameters were found as a strong function of temperature. These results indicated that the current conduction mechanism in Au/TiO 2/n-4H-SiC (SBD) well obey the FE and GD mechanism rather than other mechanisms. © 2014 AIP Publishing LLC.