Electromagnetic radiation emitting semiconductor chip and procedure for its production
View Patent ↗Semiconductor chip which emits electromagnetic radiation, and method for fabricating it. To improve the light yield of semiconductor chips which emit electromagnetic radiation, a textured reflection surface ( 131 ) is integrated on the p-side of a semiconductor chip. The semiconductor chip has an epitaxially produced semiconductor layer stack ( 1 ) based on GaN, which comprises an n-conducting semiconductor layer ( 11 ), a p-conducting semiconductor layer ( 13 ) and an electromagnetic radiation generating region ( 12 ) which is arranged between these two semiconductor layers ( 11, 13 ). The surface of the p-conducting semiconductor layer ( 13 ) which faces away from the radiation-generating region ( 12 ) is provided with three-dimensional pyramid-like structures ( 15 ). A mirror layer ( 40 ) is arranged over the whole of this textured surface. A textured reflection surface ( 131 ) is formed between the mirror layer ( 40 ) and the p-conducting semiconductor layer ( 13 ). The textured reflection surface ( 131 ) can increase the amount of light which is decoupled at the radiation-outcoupling surface ( 111 ) by virtue of the fact that a beam ( 3 ), after double reflection on the reflection surface ( 131 ), is more likely not to be totally reflected.
1. A semiconductor chip which emits electromagnetic radiation, comprising:
an epitaxially produced semiconductor layer stack based on a nitride semiconductor material, which includes an n-conducting semiconductor layers, a p-conducting semiconductor layer and an electromagnetic radiation generating region which is arranged between said n-conducting and p-conducting semiconductor layers;
a base, on which the semiconductor layer stack is arranged; and
a mirror layer, which is arranged between the semiconductor layer stack and the base and reflects electromagnetic radiation emitted by the semiconductor layer stack in a direction of the base,
wherein the mirror layer has a plurality of planar reflection sub-surfaces, which are positioned obliquely with respect to a main plane of the electromagnetic radiation-generating region and each form an angle of between 10° and 50° with respect to the main plane, and
wherein the p-conducting semiconductor layer faces the base, and the mirror layer is comprised of a reflection surface of the p-conducting semiconductor layer, which includes the plurality of planar sub-surfaces which are positioned obliquely with respect to the main plane of the electromagnetic radiation-generating region and each form the angle of between 10° and 50° with respect to the main plane.
2. The semiconductor chip which emits electromagnetic radiation according to claim 1 , wherein the reflection sub-surfaces form pyramid-like structures.
3. The semiconductor chip which emits electromagnetic radiation according to claim 1 , wherein the mirror layer includes a plurality of different layers.
4. The semiconductor chip which emits electromagnetic radiation according to claim 1 , wherein the mirror layer comprises a highly reflective layer, and at least one of a protective layer, and a joining layer.
5. The semiconductor chip which emits electromagnetic radiation according to claim 4 , wherein the highly reflective layer contains silver or aluminum.
6. The semiconductor chip which emits electromagnetic radiation according to claim 4 , wherein the protective layer contains titanium nitride.
7. The semiconductor chip which emits electromagnetic radiation according to claim 4 , wherein the joining layer contains at least one of gold, tin and an alloy of these metals.
8. The semiconductor chip which emits electromagnetic radiation according to claim 1 , wherein the semiconductor layer stack includes at least one trench which defines a plurality of individual semiconductor layer elements.
9. The semiconductor chip which emits electromagnetic radiation according to claim 8 , comprising a plurality of trenches extending such that the semiconductor layer elements, in plan view, are in the shape of one of a circle, a hexagon, a quadrilateral, a triangle or a combination of these shapes.
10. The semiconductor chip which emits electromagnetic radiation according to claim 8 , wherein the semiconductor layer elements each have a diameter or a width which includes at most ten pyramid-like structures.
11. The semiconductor chip which emits electromagnetic radiation according to claim 8 , wherein the at least one trench is at least sufficiently deep so as to at least isolate the radiation-generating region.
12. The semiconductor chip which emits electromagnetic radiation according to claim 8 , wherein a width of the at least one trench is at least double a depth of the at least one trench.
13. The semiconductor chip which emits electromagnetic radiation according to claim 8 , wherein the at least one trench is filled with an electrically insulating material which transmits radiation generated by the radiation-generating region.
14. The semiconductor chip which emits electromagnetic radiation according to claim 1 , comprising a radiation-transmitting electrically conductive contact layer arranged on the n-conducting semiconductor layer.
15. The semiconductor chip which emits electromagnetic radiation according to claim 14 , wherein the contact layer contains at least one of indium tin oxide and ZnO.
16. The semiconductor chip which emits electromagnetic radiation according to claim 1 , wherein the semiconductor chip does not contain a growth substrate.
17. The semiconductor chip which emits electromagnetic radiation according to claim 1 , wherein the p-conducting semiconductor layer is doped with magnesium.
18. The semiconductor chip which emits electromagnetic radiation according to claim 1 , wherein the base contains gallium arsenide or copper.