BROWSE
Detail
Journal Article
Microstructure and Electrical Properties of Low Temperature Processed Ohmic Contacts to p-Type GaN
- Authors
- Mi-Ran Park, Young-Joo Song, Wayne A. Anderson
- Issue Date
- 2002-10
- Citation
- ETRI Journal, v.24, no.5, pp.349-359
- ISSN
- 1225-6463
- Publisher
- 한국전자통신연구원 (ETRI)
- Language
- English
- Type
- Journal Article
- Abstract
- With Ni/Au and Pd/Au metal schemes and low temperature processing, we formed low resistance stable Ohmic contacts to p-type GaN. Our investigation was preceded by conventional cleaning, followed by treatment in boiling HNO3:HCl (1:3). Metallization was by thermally evaporating 30 nm NJ/15 nm Au or 25 nm Pd/15 nm Au. After heat treatment in O2 + N2 at various temperatures, the contacts were subsequently cooled in liquid nitrogen. Cryogenic cooling following heat treatment at 600 °C decreased the specific contact resistance from 9.84×10-4 廓cm2 to 2.65廓10-4 廓cm2 for the Ni/Au contacts, while this increased it from 1.80×10-4 廓cm2 to 3.34×10-4 廓cm2 for the Pd/Au contacts. The Ni/Au contacts showed slightly higher specific contact resistance than the Pd/Au contacts, although they were more stable than the Pd contacts. X-ray photoelectron spectroscopy depth profiling showed the Ni contacts to be Nit followed by Au at the interface for the Ni/Au contacts, whereas the Pd/Au contacts exhibited a Pd:Au solid solution. The contacts quenched in liquid nitrogen following sintering were much more uniform under atomic force microscopy examination and gave a 3 times lower contact resistance with the Ni/Au design. Current-voltage-temperature analysis revealed that conduction was predominantly by thermionic field emission.
- KSP Keywords
- 5 nm, Atomic force microscope(AFM), Au contacts, Contact resistance(73.40.Cg), Current-voltage, Depth profiling(DP), Low resistance, Low temperature(LT), Low temperature processing, Ohmic contact, P-Type GaN