Abstract: A method of producing a gallium phosphide yellow light emitting diode which includes the steps of providing a single crystal gallium phosphide substrate; growing from a hydride vapour phase a single crystal layer of nitrogen doped gallium phosphide of the same conductivity type as the substrate on a surface of the substrate such that the nitrogen content of the layer is greater than 10.sup.19 atoms/cc, the actually nitrogen content determining the wavelength of the light that can be emitted; forming at least one p-n junction with the nitrogen doped gallium phosphide layer; and forming an electrically conductive contact on each side of the p-n junction.