High voltage 4H-SiC bipolar diodes have been realised using a 40 µm thick n-type epilayer, with a doping level at 1.1E 15 cm-3. These diodes have been designed with only one Junction Termination Extension as edge termination, whereas previous high voltage diodes described in literature are protected either by mesa either by a combination of JTE and mesa. JTE are optimised using numerical computations, and are realised by a multiple aluminium implantation followed by an thermal annealing. Ohmic contacts are Ti/Al on p-type and Ni on n-type. Theoretical breakdown voltage is then calculated using realistic doping profile of aluminium in the JTE and in the emitter and is equal to 5.8 kV. The surface of the diodes is not passivated. Current voltage measurements show best Vbr at 4.8 kV when testing in Galden®. After cutting the wafer into pieces (~5´5 mm 2), Vbr seems to be reduced : best values are 3.7 kV, and are in the same range both in Galden® and in SF6. In air, Vbr is always < 1.3 kV. This shows the efficiency of the JTE. In forward bias, the current density is found in the range of 100 Acm-2 at 5 V, but decreases rapidly when duration of bias increases.