Broad spectrum light emitting semiconductor devices have conventionally been fabricated by exciting a luminous substance with a relatively narrow spectrum light source. Conventionally, in such devices a light emitting diode (LED) or laser emits light in a narrow spectrum which is shifted and/or spread to provide a broader spectrum of light. Typically, it is desirable to provide white light from a narrow spectrum light source, such as an LED or laser. Such white light sources are described, for example, in U.S. Pat. No. 6,245,259, the disclosure of which is incorporated herein by reference as if set forth fully herein.
One difficulty with the fabrication of white light devices is that, typically, the spectrum of light emitted by the devices is dependent on the spectrum of light emitted by the laser or LED and the amount of luminous substance on the device. On a single wafer or die there may be variations in the wavelength of light emitted by the particular devices on the wafer or die. Such deviations may, for example, be the result of defects in the devices or variations as a result of manufacturing tolerances. These deviations in the output wavelength of the underlying devices may result in variations in the white light emitted by the resulting devices after application and excitation of the luminous substance.