Dual metal SiC Schottky rectifiers with low power dissipation

Abstract

Nickel and titanium are the most commonly used metals for Schottky barrier diodes on silicon carbide (SiC). Ti has a low Schottky barrier height (i.e. ∼0.8 eV on 6H-SiC), whilst Ni has a higher barrier (i.e. ∼1.25 eV). Therefore, the first metal allows to achieve a low forward voltage drop V F but leads to a high leakage current. On the other hand, the second one presents the advantage of a lower reverse leakage current but has also a high value of V F. In this work, dual-metal-planar (DMP) Schottky diodes on silicon carbide are reported. The rectifying barrier was formed by using an array of micrometric Ti and Ni 2Si (nickel silicide) stripes. This low/high Schottky barrier allowed to combine the advantages of the two metals, i.e. to fabricate diodes with a forward voltage drop close to that of a Ti diode and with a level of reverse current comparable to that of a Ni 2Si diode. Under the application point of view, using this kind of barrier can lead to a reduction of the device power dissipation and an increase of the maximum operating temperature.