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-Si 1-xGex (with x=0.05) Schottky junctions has been investigated. The noise me asurements were performed over a temperature range of 77-300 K at frequenci es of 10-100 kHz. The main noise source observed in these diodes during arg on plasma sputter etching was attributed to the generation-recombination no ise. 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. Furt hermore, the activation energies of trap levels have been extracted by usin g noise spectroscopy (NS) and compared with those measured by deep-level tr ansient spectroscopy (DLTS). We found two additional trap states using NS n ot 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].