Microstructure and properties of aluminum contacts formed on GaAs(100) by low pressure chemical vapor deposition with dimethylethylamine alane source

We report on a low pressure chemical vapor deposition of metallic thin aluminum films on GaAs (001) with a dimethylethylamine alane (DMEAA) source and H₂ as a carrier gas. The deposition temperatures varied in the range 130–360°C. Integrated volumes for Al (111), (100), (110)R, and (110) grains were estimated by the x-ray diffraction technique and the growth temperature values preferred for every type of grains were observed. The experimentally observed dominance of Al(110)R over Al(110), irrespective of the substrate miscut direction, supports the GaAs(100) inner anisotropy effect on the Al grain orientation. Electrical resistivity was 5 ·cm for the best Al films. The Schottky barrier heights were near a 0.7 eV level and the ideality factor n=1.1. Nonalloyed ohmic contacts were fabricated on an n-type GaAs epitaxial layer with an additional set of Si-layers near the Al/GaAs interface. Specific contact resistance, c=7 cm², was measured. Best contacts were obtained at a deposition temperature lower than 250°C.