Very high sustainable forward current densities on 4H-SiC p-n junctions formed by VLS localized epitaxy of heavily Al-doped p ++ emitters

This study deals with the electrical characterization of PiN diodes fabricated on a 4°off-axis 4H-SiC n + substrate with a n − epilayer (1×10 16 cm −3 / 10 μm). Optimized p ++ epitaxial areas were grown by Vapour-Liquid-Solid (VLS) transport to form p + emitters localized in etched wells with 1 μm depth. Incorporated Al level in the VLS p ++ zones was checked by SIMS (Secondary Ion Mass Spectroscopy), and the doping level was found in the range of 1–3×10 20 at.cm −3 . Electrical characterizations were performed on these PiN diodes, with 800 nm deposit of aluminium as ohmic contact on p-type SiC. Electrical measurements show a bipolar behaviour, and very high sustainable forward current densities ≥ 3 kA.cm −2 , preserving a low leakage current density in reverse bias. These measurements were obtained on structures without any passivation and no edge termination.