Formation of ohmic contacts with SiC by laser ablation

A description is given of a new method for the formation of an ohmic contact with silicon carbide (SiC) single crystals, based on laser ablation of the crystal surface. It was found that regions of SiC ablated in air or in vacuum by copper vapour laser radiation (wavelength 510.6 nm, pulse duration 10 ns) become capable of reducing metals (Cu or Ni) from suitable solutions intended for autocatalytic deposition. The Raman spectra of the ablated regions demonstrate the presence of Si nanoclusters of 10 — 20 nm size, which are one of the reasons for chemical reduction of the metal. The deposited metal forms an ohmic contact with n-type SiC without additional annealing and the specific contact resistance depends weakly on the nature of the metal, amounting to 2.3 and 2.1 mΩ cm² for Cu and Ni, respectively. The mechanisms of ohmic contact formation by laser ablation are discussed.