The effect of sputtering current that flow in a carbon rod on the structural and transport properties of Si-C junction is studied. Si-C junction is fabricated by plasma sputtering in Argon gas atmosphere without catalysts with thickness of 20, 40 and 60 nm. Images of the specimen by scanning electron microscope (SEM) and atomic force microscope (AFM) show that the carbon layer is as carbon nanotubes with diameters about 20 - 30 nm. X-ray and Raman spectrums show peak characteristics of the carbon nanotubes, the G and D bands appear for all thicknesses indicating free of defect carbon nanotubes. Two parameters about the thickness of the carbon layer and the sputtering current for different thicknesses and currents were studied. Nanotubes evidence was clear. We noticed that the sputtering current and thickness of layers affect the structure of CNT layer leading to the formation of grains. Increasing plasma current led to decrease grain formation however increasing thickness ends to increase grain size; moreover it led to amorphous structure formation and this was proved through X-ray, Raman spectra and AFM images.