The aim of the present work is to grow 3C-SiC on (0001) 6H-SiC seeds using the Physical Vapour Transport (PVT) method and to study the electrical and structural properties of the grown material. Photoluminescence (PL)-mappings reveal that the overgrown layer consists predominantly of the 3C-SiC polytype and capacitance-voltage (C-V) measurements result in a net nitrogen donor concentration of 1x1016cm-3. Transmission Electron Microscopy (TEM) observations also confirm that the overgrown layer is of the 3C-SiC polytype having the cubic  crystallographic direction parallel to the c-axis of the 6H-SiC substrate. In some cases, twin crystals of 3C-SiC are formed immediately after the interface and, in a few cases, small 6H-SiC inclusions are observed in the cubic film having the same orientation as the substrate. The film near the substrate/overgrown interface shows a high density of defects such as dislocations and stacking faults (SF’s), which propagate into the overgrown layer. Finally although there is a rapid decrease of the defect density within the first 60 µm from the interface, the SF density remains almost constant within the last 100 µm below the surface.