The invention relates to a
quantum well composite LED epitaxial structure with high luminous efficiency and a preparation method thereof. The epitaxial structure is sequentially provided with a substrate, a buffer layer, an undoped GaN layer, an n-type AlGaN layer, an n-type GaN layer, an
active layer, a P-type AlGaN layer, a P-type GaN layer and a P-type InGaN
contact layer from the bottom up, wherein the
active layer comprises a lower layer multi-
quantum well structure, a constant temperature multi-
quantum well structure and an upper layer multi-
quantum well structure, the lower layer multi-
quantum well structure is formed by periodically overlying an InGaN
potential well layer and a GaN
barrier layer, the constant temperature multi-
quantum well structure is formed by periodically overlying a constant temperature InGaN
potential well layer and a constant temperature GaN
barrier layer, and the upper layer multi-quantum well structure is formed by periodically overlying the InGaN
potential well layer and the GaN
barrier layer. The preparation method is that the
layers are sequentially prepared from the bottom up in a
reaction chamber of
metal organic
chemical vapor deposition equipment. The epitaxial structure and the preparation method thereof can effectively reduce stress between well barrier interfaces, relieve bending of an energy band, and improve the efficiency of hole injection and
electron injection to an active region and the radiative recombination efficiency.