Current-conduction mechanism in Au/n-4H-SiC Schottky barrier diodes

Abstract

Au/n-4H-SiC Schottky barrier diodes (SBDs) were fabricated and their temperature and voltage dependence of saturation current (I_o), ideality factor (n), barrier height (Φ_bo), series and shunt resistances (R_s, R_sh) values were obtained by using current-voltage (I-V) measurements in the temperature range 110-400 K. The values of I_o, n and Φ_bo were found as 3.00 10^-14A, 3.41 and 0.39 eV at 110 K and 7.7510^-7A, 1.64 and 0.90 eV at 400 K, respectively. The Φ_bo-q/2kT plot was drawn to obtain an evidence of a Gaussian distribution (GD) of the barrier heights (BHs). The mean BH (Φ_bo) and standard deviation (σ_o) values have been extracted from the intercept and slope of this plot is as 1.089 eV and 0.127 V, respectively. The Φ_bo and Richardson constant (A^*) values were obtained from the modified Ln(I_o/T²)-(q²σ_s²/2k²T²) versus q/kT plot as 1.093 eV and 160.6 A.cm^-2K^-2 which can be considered as close to the theoretical value 146 A.cm^-2K^-2, respectively. Voltage dependent activation energy (E_a) value was also obtained from the In(I_o/T²)-q/kT and In(I_o/T²)-q/nkT plots in the voltage range 0.05-0.50 V with 0.05 V steps and it is found that it decreases with increasing voltage. The temperature dependence of I-V characteristics in Au/n-4H-SiC diodes can be successfully explained on the basis of a TE mechanism with GD of the BHs.