Halbleiterbauelement mit semi-isolierender Schicht für hohe Durchbruchspannungen

A semiconductor device has a first semiconductor region (13,15,17) of a first conductivity type and a second semiconductor region (14) of a second conductivity type contacted by respective first and second electrodes (6,2). A semi-insulating layer (8) extends between the first and second electrodes (6,2) and there is a first insulating (4,7) between the semi-insulating layer (8) and the first semiconductor region (13,15,17). The sheet resistivity of the semi-insulating layer (8) varies and this improves the high breakdown voltage of the p-n junction of the semiconductor device between the first and second semiconductor layers, by acting as a shield for charges included on a passivation insulation layer (19) covering the semi-insulating layer (8) and the first and second electrodes (6,2). Third semiconductor regions (16), with corresponding third electrodes (5) extend around, and are spaced from, the second semiconductor region (14). The third electrodes (5) extend over the parts of the first semiconductor region (13,15,17) adjacent the third semiconductor region (16) as this also improves the breakdown voltage. The second electrode (2) may also extend over the part of the first semiconductor region (13,15,17) adjacent the second semiconductor region (14) to cover the p-n junction therebetween.