| 摘要 |
PROBLEM TO BE SOLVED: To effectively use a GaN substrate itself as a fluorescence emitting body without excessively requiring different phosphors by a method, wherein blue and bluegreen light from a light emitting structure and yellow and orange light from the center of fluorescence of the GaN substrate are composed so as to obtain white light. SOLUTION: A GaN substrate 16 which becomes the light emitting center of fluorescence and which comprises impurities and a crystal defect and a light emitting structure 17, which is epitaxially grown on it is be composed of an LED 15. The light emitting structure 17 is a GaInN thin film and contains a p-n junction. When a current is made to flow to the p-n junction, a band gap is shifted, and light E at 400 to 500 nm is emitted. A part of the light advances to the lower side to enter the substrate 16. An oxygen, carbon or nitrogen voids to the like exixts in the GaN substrate 16, and blue color is absorbed with fluorescence at 520 to 650 nm being emitted. Fluorescence emission F in the substrate 16 is reflected by the bottom face, or it goes over the thin film 17 directly so as to go over to the outside. Light in which the LED light E is mixed with the fluorescence emission F goes to the outside, and the this is seen as white light (W=E+F). |
