The invention relates to a so-termed punchthrough diode (10) with a stack of, for example, n++, n-, p+, n++ regions (1,2,3,4). In the known diode, these semiconductor regions (1,2,3,4) are positioned in said order on a substrate (11). The diode is provided with connection conductors (5,6). Such a diode does not have a steep I-V characteristic and is therefore less suitable as a TVSD (=Transient Voltage Suppression Device). In particular at voltages below 5 volts, a punchthrough diode could form an attractive alternative as TVSD. In a punchthrough diode (10) according to the invention, a part of the first semiconductor region (1) bordering on the second semiconductor region (2) comprises a number of sub-regions (1A) which are separated from each other by a further semiconductor region (7) of the second, for example p+, conductivity type which is electrically connected to the first connection conductor (5). Such a diode has a very steep I-V characteristic, is very suitable as a TVSD and functions very well at an operating voltage below 5 volts. Preferably, the further region (7) comprises a part (7A) which is wider than the other parts thereof. The regions (1,2,3,4) may be present in two different orders within a stack positioned on the substrate (11), each of said orders having certain advantages.