Contact Resistance of Nickel/Germanium/Gold, Palladium/Germanium/Titanium/Platinum, and Titanium/Palladium Ohmic Contacts to Gallium Arsenide and its Temperature Dependence from 4.2 to 350K

摘要

The specific contact resistance, r sub c, and contact resistance, Rc, of NiGeAuand PdGeTiPt Ohmic contacts to n-GaAs and TiPd and PdGeTiPt Ohmic contacts to p+-GaAs were determined as a function of temperature between 4.2 and 350K The low r sub c obtained for some of the contacts at 4.2K implies that much of the total contact resistance measured at 4.2K in 2DEG structures lies across the n-n heterojunction(s) in series with the metal semiconductor junction. Although NiGeAu contacts have a lower contact resistance to n-GaAs, PdGeTiPt contacts, which have much better edge definition, can be substituted for the NiGeAu when they are properly annealed. Also, low resistance contacts can be made to heavily p-doped GaAs at 4.2K using either TiPd or properly annealed PdGeTiPt contacts, r sub c for the TiPd contacts annealed at 350 deg C for 15 s and at 395 deg C for 90s, and the 350 deg C/15s p-PdGeTiPt contact fit the field emission model, and the 395 deg C/90s NiGeAu, 350 deg C/15s n-PdGeTiPt, and 395 deg C/90s p-PdGeTiPt contacts can be described by the thermal field emission mode. However, the 350 deg C/15s NiGeAu and 395 deg C/90s n PdGeTiPt contacts have a much larger temperature dependence that can best be described by tunneling to deep states near the metal-semiconductor interface. p4.