Effect of Dopant Concentration on High Voltage 4H-SiC Schottky Diodes
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0911-B10-02
Effect of Dopant Concentration on High Voltage 4H-SiC Schottky Diodes Francesco La Via1, Giuseppa Galvagno1, Andrea Firrincieli1, Salvatore Di Franco1, Andrea Severino1, Stefano Leone2, Marco Mauceri2, Giuseppe Pistone2, Giuseppe Abbondanza2, Ferdinando Portuese2, Lucia Calcagno3, and Gaetano Foti3 1 CNR-IMM, Stradale Primosole 50, Catania, 95121, Italy 2 Epitaxial Technology Center, BIC Sicilia - Pantano d'Arci, Catania, 95030, Italy 3 Physics Department, Catania University, Via S. Sofia 64, Catania, 95123, Italy
ABSTRACT 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.
INTRODUCTION Silicon carbide devices are currently emerging for high-temperature, high-power, highfrequency electron applications due to the superior material properties like the wide band gap, the high saturated electron velocity and the high critical electric field [5]. However, the fabrication and the optimization of electronic devices on an industrial scale imposes an accurate knowledge of the physical parameters related to the carrier transport. Among the large variety of fabricated SiC devices the Schottky diodes are the most attractive for their very short turn-off transient which can significantly reduce the power losses in power converters [6]. However, due to the high electric fields normally encountered in SiC devices, the reverse leakage current of Schottky diodes can be significantly enhanced prior to junction breakdown due to the presence of defects in the epitaxial material more than mechanisms such us thermionic field emission or field emission. As high leakage current is undesirable, it is therefore
important to determine these current effects in order to understand the dopant limitations for the device and to obtain high forward current with as low as possible leakage currents. Another important issue is related to the possibility of SiC to operate at high temperatures. High temperature operation requires the temperature dependence of leakage currents to be known for a better understanding of the device preference under these conditions. 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 th
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