Electrical characteristics and structural properties of ohmic contacts to p-type 4H-SiC epitaxial layers

Epitaxial films grown by low-temperature liquid phase epitaxy on p-type 4H-SiC were used as strongly doped subcontact layers for making low-resistance contacts to the p-type material. The layers had a bulk resistivity of ∼0.02 Ω · cm and an aluminum atom concentration of ∼1.5×1020 cm−3. The absence of polytype inclusions and the distinct crystalline quality of the strongly doped subcontact layers was confirmed by x-ray diffraction methods. Ohmic contacts with resistivities less than 10−4 Ω · cm2 were prepared by depositing and then annealing multilayer metal mixtures containing Al and Ti. The structural properties and energy characteristics of the resulting ohmic contacts are discussed.