Beryllium doped GaN-based light emitting diode and method
The invention described herein provides a method and apparatus to realize incorporation of Beryllium followed by activation to realize p-type materials of lower resistivity than is possible with Magnesium. Lower contact resistances and more effective electron confinement results from the higher hole concentrations made possible with this invention. The result is a higher efficiency GaN-based LED with higher current handling capability resulting in a brighter device of the same area.
1. A GaN-based light emitting diode (LED) device, comprising:
a substrate member, the substrate member being selected from at least one of a sapphire member, a SiC member, a GaN member, a AlN member, or a silicon member;
a GaN buffer layer comprising a n-type doping material deposited on a surface region of the substrate member;
an AlGaN confinement layer comprising an n-type doping material deposited directly overlying the GaN n-type buffer layer;
an InGaN/GaN multi-quantum well (MQW) active region grown directly overlying the AlGaN confinement layer;
an AlGaN layer to serve as an electron confinement layer; and
optionally, an GaN layer to serve as a current spreading and ohmic contact layer grown directly overlying the undoped AlGaN confinement layer;
wherein each of the AlGaN layer and the GaN layer comprises a plurality of beryllium impurities configured using ion implantation such that a region has been damaged by the ion implantation and configured to be activated by a high temperature annealing process that comprises an isothermal anneal on the region in a hydrogen and ammonia free ambient at temperatures in the range from 700 to 900 degrees Celsius for time period of greater than one second to facilitate removal of atomic hydrogen entities from the region such that a resulting beryllium doped material characterized by a low resistivity of less than 10 ohm-cm, p-type layers to 10-3 ohm-cm.
2. The device of claim 1 wherein the electron confinement layer is a layer selected from one of:
a GaN Beryllium implanted p-type layer,
a InGaN Beryllium implanted p-type layer,
a AlInGaN Beryllium implanted p-type layer,
a graded bandgap AlxGa1-xN Beryllium implanted p-type layer, or
a graded bandgap AlxInyGa1-x-yN Beryllium implanted p-type layer.
3. The device of claim 1 wherein each of the electron confinement layer and the ohmic contact and current spreading layers comprises a magnesium doped confinement region, a current spreading region, and an ohmic contact layer provided prior to an ion implant and an annealing process.
4. The device of claim 1 wherein the current spreading layer is not optional.
5. The device of claim 1 wherein the MQW active region is optionally replaced with a doped or undoped GaN material.
6. The device of claim 1 wherein the MQW active region is optionally replaced with an doped or undoped AlGaN.
7. The device of claim 1 wherein the region is encapsulated using a nitrogen bearing material.
8. The device of claim 7 wherein nitrogen bearing material is selected from a nitride material or an ammonia material.
9. The device of claim 8 wherein the region is subjected to an isothermal anneal at temperatures greater than 800 degrees Celsius for a time period of greater than one second on the region while the region has been encapsulated.
10. The device of claim 9 wherein the region is subjected to a pulsed laser to achieve a surface temperature greater than 1000 degrees Celsius for a time period of shorter than one second.
11. A GaN-based light emitting diode (LED) device, comprising:
a substrate member, the substrate member being selected from at least one of a sapphire member, a SiC member, a GaN member, a AlN member, or a silicon member;
a GaN buffer layer comprising a n-type doping material deposited on a surface region of the substrate member;
an AlGaN confinement layer comprising an n-type doping material deposited directly overlying the GaN n-type buffer layer;
an InGaN/GaN multi-quantum well (MQW) active region grown directly overlying the AlGaN confinement layer;
an AlGaN layer to serve as an electron confinement layer; and
optionally, an GaN layer to serve as a current spreading and ohmic contact layer grown directly overlying the AlGaN confinement layer;
wherein each of the AlGaN layer and the GaN layer comprises a plurality of beryllium impurities configured using ion implantation such that a region has been damaged by the ion implantation and configured to be activated by a high temperature annealing process that comprises an isothermal anneal on the region in a hydrogen and ammonia free ambient at temperatures in the range from 700 to 900 degrees Celsius for time period of greater than one second to facilitate removal of atomic hydrogen entities from the region such that a resulting beryllium doped material characterized by a low resistivity of less than 10 ohm-cm, p-type layers to 10-3 ohm-cm.
12. The device of claim 11 wherein the electron confinement layer is a layer selected from one of:
a GaN Beryllium implanted p-type layer,
a InGaN Beryllium implanted p-type layer,
a AlInGaN Beryllium implanted p-type layer,
a graded bandgap Al x Ga 1-x N Beryllium implanted p-type layer, or
a graded bandgap Al x In y Ga 1-x-y N Beryllium implanted p-type layer.
13. The device of claim 11 wherein each of the electron confinement layer and the ohmic contact and current spreading layers comprises a magnesium doped confinement region, a current spreading region, and an ohmic contact layer provided prior to an ion implant and an annealing process.
14. The device of claim 11 wherein the current spreading layer is not optional.
15. The device of claim 11 wherein the MQW active region is optionally replaced with a doped or undoped GaN material.
16. The device of claim 11 wherein the MQW active region is optionally replaced with an doped or undoped AlGaN.
17. The device of claim 11 wherein the region is encapsulated using a nitrogen bearing material.
18. The device of claim 17 wherein nitrogen bearing material is selected from a nitride material or an ammonia material.
19. The device of claim 18 wherein the region is subjected to an isothermal anneal at temperatures greater than 800 degrees Celsius for a time period of greater than one second on the region while the region has been encapsulated.
20. The device of claim 19 wherein the region is subjected to a pulsed laser to achieve a surface temperature greater than 1000 degrees Celsius for a time period of shorter than one second.