Laser annealing of ohmic contacts on GaAs

Abstract

Backside irradiation through the substrate with a Q-switched Nd:glass laser (l = 1.06 mm) has been used to produce Au-Ge ohmic contacts on GaAs. Conventional thermal alloying was done for comparison. The structure of the contacts was investigated by 2-MeV He-ion Rutherford backscattering technique, photographs, and I-V characteristic measurements. The irradiated Au-Ge contacts exhibit good ohmic contact behavior and good surface morphology. Ohmic contacts with specific contact resistance rc less than 2×10−5 W cm2 have been measured within the laser energy density of 0.3–0.5 J/cm2, while the thermally alloyed contacts yielded rc = 1.3×10−4 W cm2.