The CdTe/Si solar cells have been fabricated on p-Si wafer by thermal evaporation method at different thicknesses of n-CdTe (100, 300, 500, and 700nm). The structural and electrical properties including x-ray diffraction, AFM analysis and I-V characteristics are studied and interpreted. For the back and front contacts, gold and indium tin oxide (ITO) are used respectively. Choosing gold as a good back contact is because of its suitable work function with respect to electron affinity and energy gap of silicon. While ITO is chosen as a good front contact for its special properties of good conductivity and transparency. XRD patterns show a good crystallinity of CdTe films and AFM images show a good smoothness of the surface topography of these films. From Hall Effect measurements, we found that the mobilityof charge carriers is 820cm 2 /V-s. From the I-V curves, we found that the quantum efficiency and fill factor have maximum values at the thickness of 500nm (=3.61%, and FF=0.39).In general, the dark current of devices is very close to zero.