Investigation of Metal Contact Stacks for Submicron GaN HEMT

Y.Knafo1, I. Topledo2, I. Hallakoun2, J.Kaplun2, G. Bunin2, t. Baksht1, B. Hadad1 and Horam Shapira1  1Department of Electrical Engineering - Physical Electronics, Tel-Aviv University, Ramat-Aviv, Israel  2Gal-El (MMIC), P.O. Box 330, Ashdod 77102, Israel  Email: Y.Knafo:

Encapsulated Ti/Al/Ni/Au metal stack for Ohmic contacts and TaN vs. Ni for Schottky contacts for submicron GaN HEMTs have been investigated.  The results show that the composition of the SiNx encapsulation layer is a dominant factor, affecting metal morphology, edge definition and e-beam lithography alignment mark detection.  The results show that TaN can be used as a Schottky gate at very high temperature applications, but Ni has superior barrier height and it is stable at 300oC. 

Keywords:  GaN HEMT, Ohmic contacts, Schottky contacts

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