Improved Ni ohmic contact on n-type 4H-SiC
- 243 Downloads
This paper presents the structural, chemical and electronic properties of Al/Ni/ Al-layers evaporated on 4H silicon carbide and then annealed at 1000°C for 5 min. The structure was investigated before and after annealing by transmission electron spectroscopy from cross-sectional specimens. With x-ray photoelectron spectroscopy, both element distribution and bonding energies were followed during sputtering through the alloyed metal-semiconductor contact. Voids are found in both annealed Ni/4H-SiC and Al/Ni/Al/4H-SiC contact layers, though closer to the metal-semiconductor interface in the former case. The first aluminum-layer is believed to prevent voids to be formed at the interface and also to reduce the oxide on the semiconductor surface. The contact was found to be ohmic with a specific contact resistance ρc - 1.8 × 10−5 Ωcm2 which is more than three times lower ρc than for the ordinary Ni/4H-SiC contact prepared in the same way.
Key wordsAl/Ni/Al/4H-SiC transmission electron microscopy x-ray photoelectron spectroscopy
Unable to display preview. Download preview PDF.
- 2.H.J. Cho, O.S. Hwang, W. Bang and H.J. Kim, Proc. 5th SiC and Related Material Conf., Washington DC, (1993), p. 663.Google Scholar
- 4.M.I. Chaudhry, W.B. Berry and M.V. Zeller, Intl. J. Electron- ics 71, 439 (1991).Google Scholar
- 6.G.L. Harris, G. Keiner and M. Shur, Properties of Silicon Carbide, ed. G.L. Harris, EMIS Datareviews Series, No.13, (INSPEC, 1995).Google Scholar
- 7.S. Liu, Proc. ICSCRM 95, Kyoto, Japan, (1995), p. 373.Google Scholar
- 8.R. Kaplan and V.M. Bermudez, Properties of Silicon Carbide, ed, G.L. Harris, EMIS Datareviews Series, No.13, (INSPEC, 1995).Google Scholar
- 10.Ts. Marinova, R. Yakimova, V. Krastev, C. Hallin and E. Janzén, J. Vac. Sci. Technol. (in press).Google Scholar
- 11.C. Hallin, R. Yakimova, V. Krastev, Ts. Marinova and E. Janzén, Proc. ICSCRM 95, Kyoto, Japan, (1995), p. 140.Google Scholar
- 12.P. Shewmon, Diffusion in Solids, (Warrendale, PA: The Minerals, Metals & Materials Society, 1989).Google Scholar