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Electrical properties of tungsten on silicon carbide (4H-SiC) Schottky diodes are investigated through the analysis of the forward current-voltage (I-V) characteristics measured at elevated temperatures within the range of 303-448 K. The subsequently derived Schottky barrier heights (SBHs) and ideality factors are found to be temperature dependent with distributions that are adequately explained within the framework of the model proposed by Tung in which he considers the barrier at a metal-semiconductor interface as consisting of locally non-uniform but interacting patches of different barrier heights embedded in a background of uniform barrier height. A uniform barrier height of 1.248 eV, a Richardson's constant of 129.95 A cm −2 K 2 and a factor T o of 23.92 K obtained agree very well with values published previously for similar Schottky barrier systems. Therefore, it has been concluded that the temperature-dependent I-V characteristics of the device can be successfully explained with lateral inhomogeneities distribution of the SBH.

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The electrical characteristics of ion-implanted guard rings for molybdenum (Mo) Schottky diodes on 4H-SiC are analyzed on the basis of the standard thermionic emission model and the assumption of a Gaussian distribution of the barrier height. For edge termination, high-resistivity guard rings manufactured by carbon and aluminum ion-implanted areas were used. Extractions of barrier heights of molybdenum on silicon carbide (4H-SiC) Schottky diodes have been performed on structures with various gate metallization, using both current-voltage-temperature (I-V-T) and capacitance-voltage (C-V) measurements. Characteristic features of the Schottky barrier height (SBH) are considered in relation to the specific dose of the carbon-or aluminum-implanted guard ring. Contacts showed excellent Schottky behavior ideality factors between 1.02 and 1.24 in the range of 303-473 K. The measured SBHs were between 0.92 and 1.17 eV in the same temperature range from I-V-T characteristics. The variations in the barrier height, which is significantly temperature-and implantation-dose-dependent, are well fitted to a single Gaussian distribution function. Experimental results agree reasonably well by using this approach, particularly for carbon implantation dose of 1.75 × 10 14 cm −2 , and a mean barrier height ( ¯ B0 ) of 1.22 eV and zero bias standard deviation σ 0 = 0.067 V have been obtained. Furthermore, the modified Richardson plot according to the Gaussian distribution model resulted in a mean barrier height ( ¯ B0 ) and a Richardson constant (A * ) of 1.22 eV and 148 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 Mo/4H-SiC contacts can be successfully explained on the basis of a thermionic emission conduction mechanism with Guassianly distributed barriers.