COMPARISON OF HIGH-TEMPERATURE THERMAL STABILITIES OF RU AND RUO2 SCHOTTKY CONTACTS TO GAAS

Abstract

Thermal behaviors of ruthenium (Ru) and ruthenium dioxide (RuO2) Schottky contacts have been compared after rapid thermal annealing at 550-900 degrees C for 30 s without arsenic overpressure or capping layer. Rutherford backscattering measurements and x-ray diffraction indicate that no metallurgical interactions take place between RuO2 and GaAs. I-V characteristics of RuO2 Schottky contacts reveal that barrier height increases from 0.83 to 0.85 eV even after RTA at 900 degrees C, in contrast with the degradation of barrier height from 0.75 to 0.59 eV for the Ru Schottky diodes. This means that RuO2 Schottky contacts have higher thermal stability than Ru contacts to GaAs. The reason is ascribed to the diffusion barrier property of RuO2 preventing the interdiffusion of Ga and As. (C) 1995 American Institute of Physics.