of gallium arsenide gaas and n doped regions 3 4 with the same doping concentration which are doped with silicon in a concentration of about 3 u00d7 10 17 cm 3 and with ohmic contacts of the composition germanium gold chromium goid ge au cr au the following dimensions were selected b 80 microns c 1 5 microns and d 1 5 microns fig3 shows the current voltage curve of the special embodiment shown in fig2 for a semiconductor diode 1 for the specially selected dimensions b c d and the specially selected materials as may be seen from the curve 8 the current i is zero through the diode 1 in the voltage range between about 2 5 v to 2 5 v on the other hand for stronger voltages either negative or positive the current changes sharply which is attributable to the tunneling of charge carriers through the center regions as a result of the special geometric design of semiconductor diodes in accordance with the invention in particular as a result of the length d of the intrinsic region 5 according to which the distance between the doped regions 3 and 4 is determined the threshold voltage of semiconductor diodes in accordance with the invention can be varied the smaller the region 5 is in fact the smaller the external voltage needed to produce a.