Ternary TiAlGe ohmic contacts for p-type 4H-SiC

Reduction of annealing temperature to prepare low resistance ohmic contact materials for p-type 4H-SiC was achieved by adding Ge to the conventional TiAl contacts. Although the binary TiAl contact is required to anneal at temperature as high as 1000degreesC to convert Schottky to ohmic behavior after deposition of the Ti and Al layers on the SiC substrate, the GeTiAl contacts provided the specific contact resistance of about 1x10(-4) Omega cm(2) by annealing at temperature as low as 600degreesC. This low annealing temperature is desirable to reduce the gate leakage current of the SiC devices. The GeTiAl ohmic contacts were thermally stable during isothermal annealing at 400degreesC subsequently after preparing the ohmic contacts by annealing at 600degreesC, which is also required by the device packaging process. (C) 2004 American Institute of Physics.