SEMICONDUCTOR DEVICE HAVING A RECTIFYING JUNCTION AND METHOD OF MANUFACTURING SAME

The invention relates to a semiconductor device having a rectifying junction (5) which is situated between two (semiconductor) regions (1, 2) of an opposite conductivity type. The second region (2), which includes silicon, is thicker and has a smaller doping concentration than the first region (1) which includes a sub-region comprising a mixed crystal of silicon and germanium. The two regions (1, 2) are each provided with a connection conductor (3, 4). Such a device can very suitably be used as a switching element, in particular as a switching element for a high voltage and/or high power. In the known device, the silicon-germanium mixed crystal is relaxed, leading to the formation of misfit dislocations. These serve to reduce the service life of the minority charge carriers, thus enabling the device to be switched very rapidly. In a device in accordance with the invention, the entire first region (1) comprises a mixed crystal of silicon and germanium, and the germanium content and the thickness of the first region (1) are selected so that the voltage built up in the semiconductor device remains below the level at which misfit dislocations develop. Surprisingly, it has been found that such a device can also be switched very rapidly, even more rapidly than the known device. The absence of misfit dislocations has an additional advantage, namely that the device is very reliable. Misfit dislocations do not develop if the product of said relative deviation in the lattice constant and the thickness of the first region is smaller than or equal to 40 nm %. A safe upper limit for said product is 30 nm %.