Impact of plasma etching on the noise performance of Ti/p-Si and Ti/p-Si1−xGex Schottky contacts

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.