led epitaxial layers are grown on a substrate . for each die , the n and p layers are electrically bonded to a package substrate that extends beyond the boundaries of the led die such that the led layers are between the package substrate and the growth substrate . the package substrate provides electrical contacts and conductors leading to solderable package connections . the growth substrate is then removed . because the delicate led layers were bonded to the package substrate while attached to the growth substrate , no intermediate support substrate for the led layers is needed . the relatively thick led epitaxial layer that was adjacent the removed growth substrate is then thinned and its top surface processed to incorporate light extraction features . there is very little absorption of light by the thinned epitaxial layer , there is high thermal conductivity to the package because the led layers are directly bonded to the package substrate without any support substrate therebetween , and there is little electrical resistance between the package and the led layers so efficiency is high . the light extraction features of the led layer further improves efficiency .