| 摘要 |
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 Si<SUB>x</SUB>N<SUB>y </SUB>(x,y>=1), Mg<SUB>w</SUB>N<SUB>z </SUB>(w,z>=1), or Al<SUB>s</SUB>In<SUB>t</SUB>Ga<SUB>1-s-t</SUB>N (0<=s,t<1, s+t<=1) 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 Al<SUB>u</SUB>In<SUB>v</SUB>Ga<SUB>1-u-v</SUB>N (0<=u,v<1, u+v<=1) 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.
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