The invention provides an epitaxial structure for optimizing an
ultraviolet light-emitting
diode (LED) luminous layer. The epitaxial structure sequentially comprises a
sapphire substrate, a high-temperature UGaN layer, an N-type GaN layer, a multi-
quantum well (MQW) structure, an active region
quantum-well luminous layer and a P-type GaN layer from bottom to top, wherein the active region
quantum-well luminous layer comprises In<x>Ga<1-x>N / AlGaN multi-quantum wells in 3-30 periods, each In<x>Ga<1-x>N / AlGaN multi-
quantum well also comprises a coverage layer in behind of a well layer, Al constituent doped in the coverage layer is gradually grown, the introduction of the Al constituent is gradually risen in a slope way, is performed at a
constant speed and finally is gradually reduced in the slope way, the time and the ratio of the two gradual changing process in the slope way are same, and the amount of the Al constituent accounts for 1-60% of Al constituent in a multi-quantum barrier. By the growth method of the epitaxial structure,
electron leakage can be reduced, the non-
radiation recombination is reduced, the
electron distribution in the quantum wells is improved, the current is uniformly extended, and the growth method is an
effective method for improving the luminous efficiency of an
ultraviolet LED; and meanwhile, the device has favorable luminous efficiency, and the photoelectric performance of the device is further improved.