Ti/Al/W Ohmic contacts to p-type implanted 4H-SiC

• Published in: Journal of applied physics Vol. 118; no. 3
• Main Authors: Vivona, M., Greco, G., Lo Nigro, R., Bongiorno, C., Roccaforte, F.
• Format: Journal Article
• Language: English
• Published: 21.07.2015
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.4927271

In this work, the morphological, structural, and electrical properties of Ti/Al/W contacts to p-type implanted silicon carbide (4H-SiC) have been monitored as a function of the annealing temperature (800–1100 °C). The increase of the annealing temperature induces a transition from a rectifying to an Ohmic behavior, with a specific contact resistance of 5.8 × 10−4 Ωcm2. The electrical behavior has been correlated with the morphological and structural analyses. In particular, the transition to an Ohmic behavior was accompanied by a gradual increase of the surface roughness and by the occurrence of a reaction leading to the formation of new phases in the stack and at the interface (TiAl3, W(SiAl)2, and TiC). The presence of Al-rich protrusions penetrating in the SiC substrate was also observed. From the temperature dependence of the electrical parameters, a barrier height of 0.69 eV for this system was determined. The thermal stability of the contacts has been demonstrated for long-term (up to 100 h) thermal cycling at 400 °C.