Silicon nanowire networks (Silicon Nanonets) is an emerging candidate technology for sensor applications. In this work, we characterized FETs (Field Effect Transistor) employing Silicon Nanonet channels. First, we compared the channel impedance among three different silicon nanonet densities: low, medium and high. Second. We compared channel impedance for channel lengths 5µm, 15µm and 30µm. Third, we evaluated the FETs performance as photodiodes. Finally, we examined the long-term stability of the FETs characteristics. We found that shorter and higher density channels have lower impedance and higher current flow. We also measured the change in the drain current of the Si nanonet FET while the He-Ne CW laser with the wavelength of 632nm irradiated its. Impedance increased by about one order-of-magnitude after 6 months of storage in open air as a result of oxidation.