The current-voltage characteristics of Au/n-GaAs Schottky diodes grown by metal-organic vapor-phase epitaxy on Ge substrates were determined in the temperature range 80-300 K. The zero-bias barrier height for current transport decreases and the ideality factor increases at low temperatures. The ideality factor was found to show the T-o effect and a higher characteristic energy. The excellent matching between the homogeneous barrier height and the effective barrier height was observed and infer good quality of the GaAs him. No generation-recombination current due to deep levels arising during the GaAs/Ge heteroepitaxy was observed in this study, The value of the Richardson constant was found to be 7.04 A K-2 cm(-2), which is close to the value used for the determination of the zero-bias barrier height.