Led epitaxial structure and led chip

An epitaxial structure for light emitting diode characterized in that the epitaxial structure for light emitting diode comprises

• a substrate, a buffer layer, a distributed Bragg reflector, and a semiconductor stack in an order from bottom to top,
• wherein the distributed Bragg reflector includes a low refractive-index film and a high refractive-index film above the low refractive-index film,
• a thickness of the high refractive-index film is thinner than an optical thickness of the high refractive-index film,
• wherein the high refractive-index film comprises:
• a first high refractive-index film;
• and
• a second high refractive-index film disposed on the first high refractive-index film, wherein a composition ratio of Al of the second high refractive-index film is lower than that of the first high refractive-index film,
• the low refractive-index film comprises AlzGa1-zAs, where z is a predetermined value in the range of 95%≥z≥100%, the first high refractive-index film comprises AlyGa1-yAs, where y is a predetermined value in the range of 70%≥y≥50%, and the second high refractive-index film comprises AlxGa1-xAs, where x is a predetermined value in the range of 65%≥x≥0.