Contacts for wide bandgap semiconductor materials

Several metal systems were evaluated to determine their ability to form electrical contacts on diamond and silicon carbide (SiC) materials. Experimental metal contacts were applied to doped samples of both diamond and SiC. The diamond contacts work reported herein focuses on the electrical and thermal stability properties of Au, Ni/W and Al/W contacts on p-type polycrystalline diamond films. These contacts on diamond exhibited perfect ohmic behavior in the as-deposited condition. Resistivities were on the order of 10(-4) ohm-cm(2) Although a number of ohmic contact systems on SiC were studied, the contact work reported herein specifically addresses the electrical performance and thermal stability of Ni/Cr/W on n-type 6H- and 4H-SiC. It was found that ohmic contacts are formed to both 6H- and 4H-SiC after annealing at 1273 K to 1323 K for 5 to 10 minutes. Contact resistivity ranges between 10(-4) and 10(-6) ohm-cm(2) with excellent reproducibility. Testing of the SIC contact system at 923 K over a period of 3000 hours revealed no degradation in performance.