Gaussian distribution of inhomogeneous barrier height in tungsten/4H-SiC (000-1) Schottky diodes

Abstract

The Gaussian distribution model have been used to analyze the anomalies observed in tungsten (W)/4H-SiC current voltage characteristics due to the barrier inhomogeneities that prevail at the metal-semiconductor interface. From the analysis of the forward I– V characteristics measured at elevated temperatures within the range of 303–448 K and by the assumption of a Gaussian distribution (GD) of barrier heights (BHs), a mean barrier height Φ ¯ B 0 of 1.277 eV, a zero-bias standard deviation σ 0 = 0.092 V and a factor T 0 of 21.69 K have been obtained. Furthermore the modified Richardson plot according to the Gaussian distribution model resulted in a mean barrier height Φ ¯ B 0 and a Richardson constant ( A ∗) of 1.276 eV and 145 A/cm 2 K 2, respectively. The A ∗ value obtained from this plot is in very close agreement with the theoretical value of 146 A/cm 2 K 2 for n-type 4H-SiC. Therefore, it has been concluded that the temperature dependence of the forward I– V characteristics of the W/4H-SiC contacts can be successfully explained on the basis of a thermionic emission conduction mechanism with Gaussian distributed barriers. In addition, a comparison is made between the present results and those obtained previously assuming the pinch-off model.