Low-ohmic contacts to /spl alpha/-SiC produced by laser technology methods

Abstract

Developed in this paper are the method and technological scheme of forming of multilayer structures W/Si/sub 3/N/sub 4//W/N to obtain ohmic contacts to /spl alpha/-SiC (N), by pulsed laser deposition (PLD) and laser annealing (LA). The optimal regimes for laser irradiation (PLI) were determined. When using Nd/sup 3+/:YAG laser, laser annealing threshold levels of ohmic contacts based on SiC/W/Si/sub 3/N/sub 4//W structures were determined. It is shown that the Q-switched regime with combined exposure of the fundamental (/spl lambda/=1.06 /spl mu/m) and double (/spl lambda/=0.53 /spl mu/m) harmonics is found to be optimal for obtaining minimal contact resistance when a YAG laser is used. It is shown that the threshold levels range of visual observed irreversible changes of resistivity with simultaneous voltage-current characteristic changes is found in area P/sub th/=10/sup 7/-2.8/spl middot/10/sup 9/ W/cm/sup 2/ in dependence from regimes of laser radiation and thickness of initial structures. Typical values of resistivity /spl rho//sub 0/ of elsewhere obtained ohmic contacts to /spl alpha/-SiC based on tungsten were close to the value /spl rho//sub 11//spl sim/5-6/spl times/10/sup -4/ /spl Omega//spl middot/cm/sup 2/.