1 Electrical and Morphological Study of a 70/30 Al-Ti Ohmic Contact to SiC J. Crofton, Department of Physics and Engineering, Murray State University, Murray, KY 42071. Dept. of Electrical Engineering, The Univ. of Kentucky, Lexington, KY 40506. S. E. Mohney, B. A. Hull, Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802. J.R. Williams, T. Isaacs-Smith, Department of Physics, Auburn University, Auburn, AL 36849. A. Syrkin, Technologies and Devices International, 12214 Plum Orchard Dr., Silver Spring, MD 20904. Abstract Al-Ti alloys are widely used as ohmic contacts to p-type SiC. This work will summarize many of the recent findings where Al-Ti contacts have been used. The composition 70 wt.% Al provides low resistance contacts with excellent electrical uniformity on p-type SiC. Specific contact resistances as low as 5x10 -6 ohm-cm 2 have been reported for contacts fabricated to heavily doped p-type layers grown using liquid phase epitaxy (LPE). Scanning electron microscopy and atomic force microscopy have been used to investigate the surface morphology and edge definition of annealed Al-Ti contacts to epitaxial layers grown by CVD. The morphology of the buried metal/semiconductor interface was examined by etching away the contact metallization and imaging the freshly exposed SiC surface. Patterned contacts exhibited good edge definition, a root-mean-square surface roughness of 11 nm, and a root-mean-square interfacial roughness of 12 nm. The deepest observed penetration of the metallization into the SiC was 65 nm, and the lateral length scale of the morphological features at the buried metal/semiconductor interface was sufficiently small compared to the active area of the contact to allow good contact-to-contact reproducibility. In addition to summarizing recent results, this work will present new data concerning the high temperature specific contact resistance of the 70/30 contact. Introduction Al-Ti alloys have been used for many years now as ohmic contacts to p-type SiC [1], [2], [3]. An examination of the binary Al-Ti phase diagram shows that there are many different phases present prior to any reaction of the metal alloy with the SiC depending on the alloy composition. Several alloys have been closely studied and include a 90/10 (weight percent of Al ), 70/30, 60/40 and 19/81 composition [4], [5]. It has been previously shown that only the alloys which produce significant reactions with the underlying SiC at the annealing temperature (1000 o C in the references cited) are capable of producing an ohmic contact. Both the 90/10 alloy and the 70/30 alloy have been studied in detail, and results indicate that the 70/30 alloy is far superior to the 90/10 alloy for achieving reproducible low resistance contacts with a minimum amount of