Electrical characterization of TiC ohmic contacts to aluminum ion implanted 4H–silicon carbide

Abstract

We report on the investigation of epitaxial TiC ohmic contacts to Al ion implanted 4H–SiC. TiC ohmic contacts were formed by coevaporation of Ti and C60 at low temperature (<500 °C). A sacrificial silicon nitride (Si3N4) layer was deposited on the silicon carbide substrate prior to Al implantation in order to reach a high Al dopant concentration at the surface while maintaining a low dose. The combination of epitaxially grown TiC and the silicon nitride layer resulted in a promising scheme to make low resistivity ohmic contacts. The lowest contact resistivity (ρC) and sheet resistance (Rs) of the implanted layer at 25 °C were as low as 2×10−5 Ω cm2 and 0.6 kΩ/□, respectively.

Ohmic contacts on silicon carbide: The first monolayer and its electronic effect

“…Much of effort expended to date to realize the ohmic contact has mainly focused on two techniques. One is the high-dose ion-implantation approach, 12,13 which can increase the carrier density of SiC noticeably and reduce its depletion width significantly so that increasing tunneling current is able to flow across barrier region. The key problem of this method is the easy formation of lattice defects or amorphization during the ion implantation.…”

Formation of ohmic contacts to α-SiC and their impact on devices

“…Although it seems to aid the formation of ohmic contacts, the mechanism by which it does so is not well understood. 31 Due to the greater difficulties with ohmic contacts to p-type SiC, many new materials (or combinations of materials) have been recently investigated: Ni/W, Al/Ni, Al/Ni/ W, 37 Pd, 40,41 Si/Pt, 42 CrB 2 , 43 W 2 B, and TiB 2 . 44 As well, new approaches such as the co-implantation of C and Al at both room and elevated temperatures have been carried out.…”

Deposition of epitaxial transition metal carbide films and superlattices by simultaneous direct current metal magnetron sputtering and C60 evaporation

“…At low deposition temperature these techniques often result in the growth of fine-grained and/or amorphous films, while large-grained or epitaxial films require much higher deposition temperatures. 14,15 The results described above clearly show that C 60 is a unique precursor in the deposition of transition metal carbide films. 9 In a series of recent publications, we have demonstrated that coevaporation of C 60 and the transition metals Ti, V, and Nb can be used to deposit epitaxial films and superlattices of TiC, VC, and NbC at very low tem-peratures.…”