The electronic semiconductor component has a crystalline wafer substrate
with an active surface and a semiconductor layer coating the active
surface. So that the semiconductor layer has a few surface defects the
crystalline wafer substrate is a sapphire or silicon carbide single
crystal and the active surface has a pit density of less than 500
pit/cm.sup.2, preferably less than 100 pit/cm.sup.2. The polishing method
for obtaining the active surface with these pit densities includes
polishing with a polishing agent, such as a silicon suspension, and a
polishing tool, which is pressed on the active surface with a pressure of
preferably from 0.05 to 0.2 kg/cm.sup.2 and moved over the active surface
with polishing motions distributed statistically and uniformly over a
360.degree. angle during polishing.