N-type gallium-nitride layer having multiple conductive intervening layers
View Patent ↗A vertical GaN-based blue LED has an n-type layer comprising multiple conductive intervening layers. The n-type layer contains a plurality of periods. Each period of the n-type layer includes a gallium-nitride (GaN) sublayer and a thin conductive aluminum-gallium-nitride (AlGaN:Si) intervening sublayer. In one example, each GaN sublayer has a thickness substantially more than 100 nm and less than 1000 nm, and each AlGaN:Si intervening sublayer has a thickness less than 25 nm. The entire n-type layer is at least 2000 nm thick. The AlGaN:Si intervening layer provides compressive strain to the GaN sublayer thereby preventing cracking. After the epitaxial layers of the LED are formed, a conductive carrier is wafer bonded to the structure. The silicon substrate is then removed. Electrodes are added and the structure is singulated to form a finished LED device. Because the AlGaN:Si sublayers are conductive, the entire n-type layer can remain as part of the finished LED device.
1. A Light Emitting Diode (LED) device for emitting non-monochromatic light, the LED device comprising:
an n-type layer that comprises a plurality of periods including a plurality of gallium-nitride (GaN) sublayers and a plurality of aluminum-gallium-nitride doped with silicon (AlGaN:Si) intervening sublayers, each of the AlGaN:Si intervening sublayers sandwiched by the gallium-nitride (GaN) sublayers, the gallium-nitride (GaN) sublayers located at top and bottom of the period, respectively;
a p-type layer;
an active layer disposed between the n-type layer and the p-type layer, wherein the active layer includes an amount of indium;
a conductive carrier;
a first electrode; and
a second electrode adapted to conduct a current, wherein the current flows from the second electrode, through the p-type layer, through the active layer, through the n-type layer, and to the first electrode thereby causing the non-monochromatic light to be emitted.
2. The LED device of claim 1 , wherein the n-type layer has a thickness of at least two thousand nanometers.
3. The LED device of claim 1 , wherein each GaN sublayer has a thickness of less than one thousand nanometers, and wherein each AlGaN:Si intervening sublayer has a thickness of less than twenty-five nanometers.
4. The LED device of claim 1 , wherein the AlGaN:Si intervening sublayers are conductive, and wherein the AlGaN:Si intervening sublayers have a silicon concentration greater than 1×10 18 atoms/cm 3 .
5. The LED device of claim 1 , wherein the n-type layer has a roughened surface.
6. The LED device of claim 1 , further comprising:
a eutectic bond metal layer disposed between the conductive carrier and the p-type layer.
7. The LED device of claim 1 , wherein each of the GaN sublayers has a thickness that is substantially greater than one hundred nanometers and is less than one thousand nanometers.
8. The LED device of claim 1 , wherein the current flows from the second electrode, through the conductive carrier, through the p-type layer, through the active layer, through the n-type layer, and to the first electrode thereby causing the non-monochromatic light to be emitted.
9. A Light Emitting Diode (LED) device comprising:
an n-type layer comprising a plurality of periods, wherein each period of the n-type layer includes a gallium-nitride (GaN) sublayer and an aluminum-gallium-nitride doped with silicon (AlGaN:Si) intervening sublayer, wherein each GaN sublayer has a thickness that is substantially greater than one hundred nanometers and is less than one thousand nanometers, wherein each AlGaN:Si intervening sublayer has a thickness of less than twenty-five nanometers, wherein each AlGaN:Si intervening sublayer has a silicon concentration greater than 1×10 18 atoms/cm 3 , and wherein the n-type layer has a thickness of at least two thousand nanometers;
a p-type layer; and
an active layer disposed between the n-type layer and the p-type layer, wherein current flow between the p-type layer and the n-type layer causes the LED device to emit light.
10. The LED device of claim 9 , further comprising:
a carrier; and
a layer of bond metal disposed between the p-type layer and the carrier.
11. The LED device of claim 10 , further comprising:
a first electrode; and
a second electrode, where the current flow flows from the second electrode in a current path through the carrier, through the bond metal, through the p-type layer, through the active layer, through the n-type layer, and to the first electrode.
12. A Light Emitting Diode (LED) device comprising:
an n-type layer comprising a plurality of periods, wherein each period of the n-type layer includes:
a gallium-nitride (GaN) sublayer, wherein each GaN sublayer has a thickness that is substantially greater than one hundred nanometers and is less than one thousand nanometers; and
a compressive strain layer that provides a compressive strain to the GaN sublayer and conducts current;
a p-type layer; and
an active layer disposed between the n-type layer and the p-type layer, wherein current flow between the p-type layer and the n-type layer passes through the compressive strain layer of each period of the n-type layer and causes the LED device to emit light.
13. The LED device of claim 12 , wherein the current is conducted between the GaN sublayers.
14. The LED device of claim 13 , wherein the compressive strain layer is a sublayer that has a thickness of less than twenty-five nanometers.
15. The LED device of claim 14 , wherein the compressive strain layer is an aluminum-gallium-nitride doped with silicon (AlGaN:Si) intervening sublayer that has a thickness of less than twenty-five nanometers.