A GaN-based LED structure is provided so that the brightness and luminous efficiency
of the GaN-based LED are enhanced effectively. The greatest difference between
the GaN-based LEDs according to the invention and the prior arts lies in the addition
of a masking buffer layer on top of the p-type contact layer and a p-type roughened
contact layer on top of the masking buffer layer. The masking buffer layer could
be formed using MOCVD to deposit SixNy (x,y1), MgwNz
(w,z1), or AlsIntGa1-s-tN (0s,t1,
s+t1) heavily doped with Si and/or Mg. The masking buffer layer is actually
a mask containing multiple randomly distributed clusters. Then, on top of the masking
buffer layer, a p-type roughened contact layer made of p-type AluInGa1-u-vN
(0u,v1, u+v1) is developed. The p-type roughened
contact layer does not grow directly on top of the masking buffer layer. Instead,
the p-type roughened contact layer starts from the top surface of the underlying
p-type contact layer not covered by the masking buffer layer's clusters. The p-type
roughened contact layer then grows upward until it passes (but does not cover)
the mask of the masking buffer layer for a specific distance. The total internal
reflection that could have been resulted from the GaN-based LEDs' higher index
of refraction than that of the atmosphere could be avoided. The GaN-based LEDs
according to the present invention therefore have superior external quantum efficiency
and luminous efficiency.