A light emitting diode includes a substrate having a body of single crystalline semiconductor material, preferably a Group III-V compound or alloy thereof, on a surface of the substrate. The body includes a window layer directly on the substrate and one or more other layers on the window layer. The layers of the body are of appropriate conductivety types to form a recombination region in which light can be generated. The substrate has an opening therethrough to the window layer. The window layer is of a material which is substantially transparent to the light generated in the recombination region and is of a thickness, 15 to 30 microns, to provide rigidity to the diode.