The effect of plasma etching on the noise properties of Ti/p-Si and Ti/p-Si1-xGex (with x=0.05) Schottky junctions has been investigated. The noise measurements were performed over a temperature range of 77-300 K at frequencies of 10-100 kHz. The main noise source observed in these diodes during argon plasma sputter etching was attributed to the generation-recombination noise. From the analysis of the noise data, we have determined the interface state density and evaluated the introduced damage. The results indicate two optimum operating temperatures where low-noise level can be achieved. Furthermore, the activation energies of trap levels have been extracted by using noise spectroscopy (NS) and compared with those measured by deep-level transient spectroscopy (DLTS). We found two additional trap states using NS not detected by DLTS measurements. Finally, a noise comparison between Ti/p-Si and Ir/p-Si fabricated on an unetched substrate has been made. (C) 2000 American Institute of Physics. [S0021-8979(00)00608-3].