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 mm$^2$. 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 $\Phi_{\mathrm{B}}$ = 1.16 eV, ideality factor $n$ = 1.01, and series resistance $R_s$ = 2.2 $\Omega$ (32 m$\Omega$ cm$^2$). The value of $R_s$ is governed by the resistance of the blocking epitaxial $n$-base (impurity concentration $N$ = 9 $\times$ 10$^{14}$ cm$^{-3}$, $n$-layer thickness $d$ = 34 $\mu$m). 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 $\mu$A). 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.
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