Laser‐annealed ohmic contacts for GaAs microwave devices

We have produced ohmic contacts of excellent electrical and morphological quality on GaAs by means of laser‐induced annealing. A systematic investigation was conducted of the effects of different metal combinations, substrates and laser parameters on the quality of ohmic contacts formed by the laser technique. Using a scanning cw argon laser we have successfully annealed contacts for a number of 1‐μm gate microwave FETs. The I‐V characteristics of the contacts, as well as the dc performance of the finished devices, compare very favorably with thermally annealed control samples. it is noteworthy that the surface morphology of the laser‐annealed contacts is far superior to those formed by conventional techniques.