thickness of the ohmic metal layer 214 is greater than 10 u00e5 in the second embodiment of present invention the metal electrode 212 and the ohmic metal layer 214 are formed respectively on the same side of the substrate 202 then a thermal annealing step is conducted on the ohmic metal layer such that the ohmic metal ions diffuse onto the second surface of the epitaxial structure 200 in the second embodiment of present invention the annealing temperatures are 200 to 700 u00b0 c and more preferably 300 to 500 u00b0 c after the annealing step an etching step is conducted to remove the ohmic metal layer and form the structure illustrated in fig2 b fig2 c illustrates a cross sectional structure of the led element after the transparent electrode layer 216 is formed over the second surface of the epitaxial structure 200 after removing the ohmic metal layer 214 a transparent electrode layer 216 is deposited over the second surface of the epitaxial structure 200 the transparent electrode layer 216 is a layer of conductive materials such as ino cdsio zno mgo sio tiwn or ito and preferably ito finally a metal pad 218 is formed on the transparent electrode layer 216 to complement an led device fig3 u2013 3c illustrate a series of cross sectional structures.