III-NITRIDE LIGHT EMITTING DEVICE WITH CURVATURE CONTROL LAYER
A semiconductor structure comprises a III-nitride light emitting layer disposed between an n-type region and a p-type region. The semiconductor structure further comprises a curvature control layer grown on a first layer. The curvature control layer is disposed between the n-type region and the first layer. The curvature control layer has a theoretical a-lattice constant less than the theoretical a-lattice constant of GaN. The first layer is a substantially single crystal layer.
1 - 12 . (canceled)
13 . A method comprising:
growing over a substrate a substantially single crystal first layer;
growing a curvature control layer on the substantially single crystal first layer; and
growing a III-nitride light emitting layer disposed between an n-type region and a p-type region; wherein:
the curvature control layer has a theoretical a-lattice constant less than a theoretical a-lattice constant of GaN;
the curvature control layer is disposed between the n-type region and the substantially single crystal first layer.
14 . The method of claim 13 wherein the curvature control layer is grown at a slower rate than the first layer.
15 . The method of claim 13 wherein a composition and thickness of the curvature control layer are selected to at least partially compensate for thermal compressive stress induced in the first layer during cool-down from an elevated growth temperature.
16 . The method of claim 13 wherein growing a substantially single crystal first layer comprises growing the substantially single crystal first layer by chemical vapor deposition.
17 . The method of claim 13 wherein growing a substantially single crystal first layer comprises growing the substantially single crystal first layer by metal-organic chemical vapor deposition.
18 . The method of claim 13 wherein growing a substantially single crystal first layer comprises growing the substantially single crystal first layer by molecular beam epitaxy.
19 . The method of claim 13 wherein the curvature control layer comprises aluminum.
20 . The method of claim 13 wherein the curvature control layer is AlGaN.
21 . The method of claim 20 wherein the curvature control layer has an AN composition greater than 0% and less than 10%.
22 . The method of claim 13 wherein the curvature control layer is AlInGaN.
23 . The method of claim 13 wherein the curvature control layer has a theoretical a-lattice constant between 3.165 and 3.188 Å.
24 . The method of claim 13 wherein the curvature control layer has a theoretical a-lattice constant between 3.180 and 3.184 Å.
25 . The method of claim 13 wherein:
the curvature control layer is an Al x In y Ga 1−x−y N layer having a theoretical a-lattice constant calculated according to a AlInGaN =(a AlN )x+(a InN )y+(a GaN )(1−x−y) where a AlN is 3.111 Å, a InN is 3.533 Å, and a GaN is 3.189 Å; and
the theoretical a-lattice constant of the curvature control layer is less than 3.189 Å.
26 . The method of claim 13 wherein growing a substantially single crystal first layer comprises growing the substantially single crystal first layer in tension.