Studies of aluminum Schottky barrier gate annealing on GaAs FET structures

Controlled annealing experiments on special GaAs FET structures have been used to assess the integrity of Al/ nGaAs Schottky barrier gates. Metallurgical properties of the Al/ nGaAs interface were analyzed using microspot Auger electron spectroscopy. Results indicate interdiffusion between Al and GaAs at the baseline annealing temperature of 275°C. At this temperature the three terminal static FET parameters were unaffected by the annealing, but the two terminal gate/source static characteristic was somewhat improved over unannealed control FETs. Annealing the Al gate up to 450°C does not appear to be harmful to the gate/source two terminal static characteristic although at this temperature three terminal static FET characteristics are severely degraded. The Al/ nGaAs interface is assessed as being both metallurgically and electrically stable when employed in inert ambient environments up to 275°C for 24 hr.