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Practical design of high-voltage SiC Schottky rectifiers requires the understanding of the influence of the epitaxial dopant concentration on the reverse and forward characteristics. This work analyzes the correlation between the dopant concentration and the I-V characteristics of Schottky diodes for a critical concentration range where the leakage current variations are more evident. The details of how high temperatures affect the properties of junctions have been carefully described to obtain further improvement in the future by proper device optimization. Dopant concentration of about 1.2 × 1016 cm-3 gives the best results in reverse characteristics without great losses in forward currents.

The growth rate of 4H-SiC epi layers has been increased by a factor 3 (up to 18μm/h) with respect to the standard process with the introduction of HCl in the deposition chamber. The epitaxial layers grown with the addition of HCl have been characterized by electrical, optical and structural characterization methods. An optimized process without the addition of HCl is reported for comparison. The Schottky diodes, manufactured on the epitaxial layer grown with the addition of HCl at 1600 °C, have electrical characteristics comparable with the standard epitaxial process with the advantage of an epitaxial growth rate three times higher.

The results of a new epitaxial process using an industrial 6x2'' wafer reactor with the introduction of HCl during the growth have been reported. A complete reduction of silicon nucleation in the gas phase has been observed even for high silicon dilution parameters (Si/H"2>0.05%) and an increase of the growth rate until about [email protected]/h has been measured. Photoluminescence at room temperature and at 50K was used for defects quantification and distribution. On these wafers grown using HCl high voltage Schottky diodes have been realized. The diodes were analyzed by current-voltage (I-V) characteristics.