The n-type GaN layers of high power blue light-emitting diodes (LEDs) were roughened successfully and formed a "cone-like" surface by photo-enhanced chemical (PEC) etching method. As a result, the extraction efficiency of the surface roughened LED increased. A simple model has been constructed to explain the relationship between the hexagonal cones and the extraction efficiency of roughened surface. A promising effect as high as 2.5 folds of surface roughing was predicted by the model. (c) 2006 Elsevier B.V. All rights reserved.