IMPROVEMENT IN LIGHT EXTRACTION USING FEATURE SIZE AND SHAPE CONTROL IN LED SURFACE ROUGHENING

摘要

PROBLEM TO BE SOLVED: To further increase the light extraction efficiency of a light emitting device.SOLUTION: Structural characteristics of a light-exiting surface (225) of a light emitting device (200) are controlled to increase the light extraction efficiency of that surface when the surface is roughened. A light emitting surface (225) comprising layers of materials different in durability against the roughening process exhibits higher light extraction efficiency than a substantially uniform light emitting surface exposed to the same roughening process. In a GaN-type light emitting device (200), a thin layer of AlGaN material on or near the light-exiting surface (225) creates sharper features after etching than features created by conventional etching of a surface comprising only GaN material.SELECTED DRAWING: Figure 2C