Growth of AlF3 thin films on GaAS(110). Structure and chemical stability

The growth process of AlF3 films on GaAs(110), from submonolayer coverage u p to several layers, have been characterized by means of Auger electron spe ctroscopy (AES), ion sputter depth profiling, and direct recoiling spectros copy with time of flight analysis (TOF-DRS). The chemical composition and t he surface structure were studied for films grown at room temperature (RT) and after annealing the films up to 400 degreesC. The films grow stoichiometrically at RT and no ordering was found in this c ase. The post-annealing of the AlF3 films produces a loss of fluorine, and a chemical reduction of aluminum with the appearance of a metallic phase. A ES and TOF-DRS combined measurements show that while F atoms escape through the surface, metallic AI diffuse into the substrate substituting Ga atoms. (C) 2001 Elsevier Science B.V. All right reserved.