In one embodiment of the invention, a bonding material is used to bond a substitute substrate to the LED, wherein the bonding material does not including gold or tin. The bonding material preferably includes gallium (Ga), such as a combination of Ga and Al or Cu. This bonding material has high thermal conductivity, high strength, high temperature stability and is low cost. In another embodiment of the invention, the substitute substrate is first thinned before it is bonded to the LED structure, so that the substitute substrate is flexible and conforms to the shape of the LED structure. In yet another embodiment of the invention, an apparatus is used for bonding a substitute substrate to a LED which includes a plurality of semiconductor epitaxial layers, said semiconductor epitaxial layers having been grown on the growth substrate so that said semiconductor epitaxial layers are curved in shape. The apparatus includes a conduit for evacuating a region near the substitute substrate on a side of the substitute substrate that is opposite to that of said semiconductor epitaxial layers. Gas pressure is applied on the semiconductor epitaxial layers, and the substitute substrate conforms to the shape of said semiconductor epitaxial layers as a result of pressure applied. A bonding material is used for bonding said substitute substrate to the semiconductor epitaxial layers.