High-voltage (3.3 kV) 4H-SiC JBS diodes

Abstract

High-voltage 4H-SiC junction-barrier Schottky (JBS) diodes have been fabricated and studied. The working area of the diodes (anode contact area) is 1.44 mm2. At currents in the range from 10−11 to 1.5 A, the forward current-voltage characteristic of the diodes is described in terms of the thermionic emission model, with the series resistance taken into account: Schottky barrier height ΦB = 1.16 eV, ideality factor n = 1.01, and series resistance Rs = 2.2 Ω (32 mΩ cm2). The value of Rs is governed by the resistance of the blocking epitaxial n-base (impurity concentration N = 9 × 1014 cm−3, n-layer thickness d = 34 μm). The diodes can block a reverse voltage of at least 3.3 kV (with a leakage current at room temperature on the order of 1 μA). It is suggested that the leakage mechanism is associated with crystal lattice defects (dislocations) in SiC. It is shown that the reverse-recovery characteristics of the diodes are determined by the flow of a purely capacitive reverse current.