III-nitride light emitting diodes with tunnel junctions wafer bonded to a conductive oxide and having optically pumped layers
A III-nitride optoelectronic device includes at least one n-type layer, an active region grown on or above the n-type layer, at least one p-type layer grown on or above the active region, and a tunnel junction grown on or above the p-type layer. A conductive oxide may be wafer bonded on or above the tunnel junction, wherein the conductive oxide comprises a transparent conductor and may contain light extraction features on its non-bonded face. The tunnel junction also enables monolithic incorporation of electrically-injected and optically-pumped III-nitride layers, wherein the optically-pumped III-nitride layers comprise high-indium-content III-nitride layers formed as quantum wells (QWs) that are grown on or above the tunnel junction. The optically-pumped high-indium-content III-nitride layers emit light at a longer wavelength than the electrically-injected III-nitride layers.
1. A method for fabricating a III-nitride optoelectronic device, comprising:
wafer bonding a conductive oxide to one or more epitaxially-grown III-nitride layers, wherein:
the III-nitride layers include at least one n-type layer, an active region grown on or above the n-type layer, and at least one p-type layer grown on or above the active region;
the III-nitride layers include a tunnel junction grown on or above the p-type layer; and
the conductive oxide is an impurity-doped n-type conductive oxide wafer bonded on or above a highly-doped n-type layer of the tunnel junction.
2. The method of claim 1 , wherein at least one n-type current spreading layer is grown on or above the tunnel junction and the conductive oxide is wafer bonded on or above the n-type current spreading layer.
3. The method of claim 1 , wherein the conductive oxide is a transparent conductor.
4. The method of claim 3 , wherein the conductive oxide is Ga 2 O 3 .
5. The method of claim 3 , wherein the conductive oxide is ZnO.
6. The method of claim 3 , wherein the conductive oxide is TiO 2 .
7. The method of claim 3 , wherein the conductive oxide is ITO.
8. The method of claim 1 , wherein the conductive oxide contains light extraction features on its non-bonded face.
9. The method of claim 1 , wherein the tunnel junction acts as a p-contact.
10. The method of claim 1 , wherein the conductive oxide acts as a current spreading layer.
11. The method of claim 1 , wherein the conductive oxide acts as an n-contact.
12. The method of claim 1 , wherein the impurity-doped n-type conductive oxide wafer has a graded doping profile.
13. The method of claim 1 , wherein a highly-doped p-type layer of the tunnel junction is grown by metal organic chemical vapor deposition (MOCVD) and the highly-doped n-type layer of the tunnel junction is regrown by ammonia molecular beam epitaxy (MBE).
14. A III-nitride optoelectronic device, comprising:
a conductive oxide wafer bonded to one or more epitaxially-grown III-nitride layers, wherein:
the III-nitride layers include at least one n-type layer, an active region grown on or above the n-type layer, and at least one p-type layer grown on or above the active region;
the III-nitride layers include a tunnel junction grown on or above the p-type layer; and
the conductive oxide is an impurity-doped n-type conductive oxide wafer bonded on or above a highly-doped n-type layer of the tunnel junction.