The behaviour of Sn/Pd/n-GaAs metallization under thermal treatment

The thermal stability of Sn/Pd/n/sup +/-GaAs ohmic contacts was investigated at 300 and 400/spl deg/C. The majority of contact structures are possible to anneal according to the annealing optimization at one temperature, but the dependence of the contact resistivity on the annealing temperature shows two minima in the case of the Sn(55 nm)/Pd(5 nm) structure. The thermal stability of the structure is better after the annealing at temperatures from the higher temperature minimum. The etching of GaAs wafers before the metal deposition in concentrate HCl produces the best thermal stability.