A bipolar high voltage/power semiconductor device has a low voltage terminal and a high voltage terminal. The device has a drift region of a first conductivity type and having first and second ends. In one example, a region of the second conductivity type is provided at the second end of the drift region connected directly to the high voltage terminal. In another example, a buffer region of the first conductivity type is provided at the second end of the drift region and a region of a second conductivity type is provided on the other side of the buffer region and connected to the high voltage terminal. Plural electrically floating island regions are provided within the drift region at or towards the second end of the drift region, the plural electrically floating island regions being of the first conductivity type and being more highly doped than the drift region.