Abstract: A semiconductor device, for example a p-i-n diode, comprises a corrugated semiconductor body having a plurality of complementary grooves and ridges on opposite sides of the body. The junction between the p-type region and the n-type intrinsic region has substantially the same configuration as, and extends substantially parallel to, the surface, while the junction between the n-type region and the intrinsic region similarly extends substantially parallel to the surface. Devices with narrow intrinsic regions can be made accurately by diffusion of the p-type region and the n-type region because the whole of the diode can be made relatively thin, for example, 90 micrometers without sacrificing strength and rigidity. In comparison with an equivalent planar device, the active area and current handling capability is increased. To avoid premature breakdown the diode may be surrounded by a thicker peripheral portion.