▎ 摘　　要

NOVELTY - The LED (40) has a sapphire substrate (100) comprising an epitaxial growth surface. A semiconductor epitaxial layer is formed on the epitaxial growth surface of the substrate, and comprises a first semiconductor layer (120), an active layer (130) and a second semiconductor layer (140). A first electrode (150) is electrically connected with the second semiconductor layer. A second electrode (160) is electrically connected with the first semiconductor layer. A graphene layer (110) is located between the active layer and the first semiconductor layer, and defines a set of apertures. USE - LED for use as light source in an optical imaging system e.g. display and projector. ADVANTAGE - The LED has higher energy conversion efficiency, higher radiance, longer lifetime, higher response speed and reliability. The LED allows a free-standing carbon nanotube structure to sustain the weight so as to avoid damage and to ensure structural integrity when the structure is hoisted by a portion. The LED allows extracting direction of light to be changed by grooves of patterned depression and the graphene layer, so that the light extraction efficiency is improved. DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of an LED. LED (40) Sapphire substrate (100) Graphene layer (110) Semiconductor layers (120, 140) Active layer (130) Electrodes (150, 160)