Comparison of electrical properties of ohmic contact realized on p-type 4H-SiC

D M Nguyen (1, 2) , Christophe Raynaud (1, 2) , Mihai Lazar (1, 2) , H Vang (1, 2) , Dominique Planson (1, 2)

1 EE - Ampère, Département Energie Electrique
2 INSA Lyon - Institut National des Sciences Appliquées de Lyon

N+ 4H-SiC commercial substrates with n-type epilayers have been used to realize bipolar diodes and TLM structures. The p-type emitter of diodes was realized by Al implantations followed by a post-implantation annealing with or without a graphite capping layer. Ohmic contacts were formed by depositing Ti/Ni on the backside and Ni/Al on the topside of the wafer. It appears that capping the sample during the annealing reduces considerably the surface roughness and the specific contact resistance. Sheet resistance and specific contact resistance as low as 2kΩ/□ and respectively 1.75×10-4 Ωcm² at 300 K have been obtained. I-V measurements as a function of temperature have been performed from ~100 to ~500 K. The variations of the series resistance vs. temperature can be explained by the freeze-out of carriers and by the variation of carrier mobility.

Mots clés: ohmic contact; surface roughness; Graphite cap; Specific resistance; TLM

Domaines: Sciences de l'ingénieur [physics]; Energie électrique

D M Nguyen, Christophe Raynaud, Mihai Lazar, H Vang, Dominique Planson. Comparison of electrical properties of ohmic contact realized on p-type 4H-SiC. ICSCRM'2007, Oct 2007, Otsu, Japan. ⟨hal-02961607⟩