Schottky characteristics and interfacial defects were investigated in WSi/GaAs and Pd/GaAs systems. In as-deposited WSi/GaAS systems, no EL2 signal was found but a new sputtering-induced defect (ED5) was detected near the interface. After annealing, EL2 appeared and ED5 disappeared. The disappearance of ED5 was correlated with improvement of the ideality factor. In Pd/GaAS systems, change of EL2 density and the broadening of EL2 spectrum is noticeable as compared with the Au/GaAs system. The authors propose a hypothetical model, that reaction of Pd with GaAs may extract excess arsenic atoms near the interface and reduce the concentration of EL2.