The development of a full-vertical GaN p-i-n rectifier on a 6H n-type SiC substrate by employing a conducting AlxGa1-xN:Si (x=∼0.1) buffer layer scheme is reported. In this vertical configuration, the n contact is made on the backside of the SiC substrate using a Ni/Au metallization scheme. Epitaxial layers are grown by low-pressure metal organic chemical vapor deposition. The AlxGa1-xN:Si nucleation layer is proven to provide excellent electrical properties while also acting as a good buffer layer for subsequent GaN growth. The reverse breakdown voltage for a relatively thin 2.5 μm thick i region was found to be over -330 V. The devices also show a low on resistance of Ron of 7.5×10-3 Ω cm2. This full-vertical configuration provides the advantage of the reduction of sidewall damage from plasma etching and lower forward resistance due to the reduction of current crowding in the bottom n-type layer.