Light emitting device, display apparatus including the same, and method of manufacturing the same
A light emitting device may be a bar-type light emitting device and include a n-GaN semiconductor layer, a p-GaN semiconductor layer spaced apart from the n-GaN semiconductor layer, an active layer arranged between the n-GaN semiconductor layer and the p-GaN semiconductor layer, and a strain relaxing layer including indium clusters and voids.
1 . A Gallium-Nitride light emitting device comprising:
a n-GaN semiconductor layer doped with an n-type dopant;
a p-GaN semiconductor layer spaced apart from the n-GaN semiconductor layer and doped with a p-type dopant;
an active layer arranged between the n-GaN semiconductor layer and the p-GaN semiconductor layer, the active layer comprising at least one of quantum well configured to emit light; and
a strain relaxing layer arranged between the active layer and the n-GaN semiconductor layer and comprising a plurality of indium clusters and a plurality of voids and not comprising the at least one of quantum well, the strain relaxing layer relaxing strain generated by a lattice constant difference between the n-GaN semiconductor layer and the active layer; and
a planarization layer contacting a top surface of the strain relaxing layer between the active layer and the strain relaxing layer, the planarization layer planarizing the top surface of the strain relaxing layer and having a thickness that is less than the thickness of the strain relaxation layer,
wherein the lattice constant difference between the n-GaN semiconductor layer and the active layer is greater than or equal to 0.02 angstroms and less than or equal to 0.05 angstroms, and
an indium content of the active layer is greater than or equal to 30% and an indium content of the strain relaxing layer is greater than or equal to 5% and less than 30%,
wherein a ratio of a total volume of the indium clusters to a total volume of the strain relaxing layer is greater than or equal to 0.01 and less than or equal to 0.3 and a ratio of a total volume of the voids to a total volume of the strain relaxing layer is more than or equal to a ratio of a total volume of the indium clusters to the total volume of the strain relaxing layer.
2 . The Gallium-Nitride light emitting device of claim 1 , wherein each of the plurality of indium clusters comprises two or more indium atoms.
3 . The Gallium-Nitride light emitting device of claim 2 , wherein for each of the plurality of indium clusters, the two or more indium atoms are metallically bonded.
4 . The Gallium-Nitride light emitting device of claim 1 , wherein a ratio of a total volume of the indium clusters to a total volume of the strain relaxing layer is less than or equal to a ratio of a total volume of the voids to the total volume of the strain relaxing layer.
5 . The Gallium-Nitride light emitting device of claim 1 , wherein a ratio of a total volume of the indium clusters to a total volume of the strain relaxing layer is greater than or equal to 0.01 and less than or equal to 0.3.
6 . The Gallium-Nitride light emitting device of claim 1 , wherein the strain relaxing layer comprises In x-y Ga 1-x N (0.05≤x-y<0.30).
7 . The Gallium-Nitride light emitting device of claim 1 , wherein a size of each of the plurality of voids is greater than or equal to about 10 nm and less than or equal to about 500 nm.
8 . The Gallium-Nitride light emitting device of claim 1 , wherein the active layer is configured to emit light having a wavelength of about 560 nm to about 750 nm.
9 . The Gallium-Nitride light emitting device of claim 1 , wherein a width of the Gallium-Nitride light emitting device is about 0.3 μm to about 1 μm, and
wherein a ratio of a length of the Gallium-Nitride light emitting device to the width of the Gallium-Nitride light emitting device is greater than or equal to 3.
10 . A display apparatus comprising:
a display device layer comprising a plurality of light emitting devices; and
a driving device layer comprising a plurality of transistors electrically connected to the plurality of light emitting devices, the driving device layer configured to drive the plurality of light emitting devices,
wherein at least one of the plurality of light emitting devices comprises the Gallium-Nitride light emitting device of claim 1 .
11 . The display apparatus of claim 10 , wherein the at least one of the plurality of light emitting devices is configured to emit light having a wavelength of about 500-560 nm to about 750 nm.
12 . The display apparatus of claim 10 , wherein the plurality of light emitting devices further comprises a first light emitting device configured to emit light having a wavelength of about 620 nm to about 750 nm, a second light emitting device configured to emit light having a wavelength of about 495 nm to about 570 nm and a third light emitting device configured to emit light having a wavelength of about 420 nm to about 495 nm.
13 . The display apparatus of claim 12 , wherein the first light emitting device, the second light emitting device, and the third light emitting device have indium contents different from each other.
14 . A method of manufacturing a Gallium-Nitride light emitting device, the method comprising:
growing a n-GaN semiconductor layer on a base substrate;
growing a strain source layer comprising indium on the n-GaN semiconductor layer;
heat-treating the strain source layer to form a strain relaxing layer comprising a plurality of indium clusters and a plurality of voids;
growing a planarization layer on a top surface of the strain relaxing layer, the planarization layer planarizing the top surface of the strain relaxing layer and having a thickness that is less than a thickness of the strain relaxing layer;
growing an active layer on planarization layer, the active layer comprising at least one of quantum well configured to emit light;
growing a p-GaN semiconductor layer on the active layer to form a Gallium-Nitride light emitting structure,
wherein the strain relaxing layer does not comprise the at least one of quantum well, and the strain layer relaxes a strain generated by a lattice constant difference between the n-GaN semiconductor layer and the active layer, and
wherein the lattice constant difference between the n-GaN semiconductor layer and the active layer is greater than or equal to 0.02 angstroms and less than or equal to 0.05 angstroms, and
an indium content of the active layer is greater than or equal to 30% and an indium content of the strain relaxing layer is greater than or equal to 5% and less than 30%,
wherein a ratio of a total volume of the indium clusters to a total volume of the strain relaxing layer is greater than or equal to 0.01 and less than or equal to 0.3 and a ratio of a total volume of the voids to a total volume of the strain relaxing layer is more than or equal to a ratio of a total volume of the indium clusters to the total volume of the strain relaxing layer.
15 . The method of claim 14 , wherein the heat-treating of the strain source layer comprises applying, to the strain source layer, a heat-treating temperature higher than a growth temperature of the strain source layer.
16 . The method of claim 15 , wherein the heat-treating temperature is at least 100° C. greater than the growth temperature.
17 . The method of claim 14 , wherein the heat-treating of the strain source layer comprises separating indium atoms in the strain source layer from other materials in the strain source layer and causing the separated indium atoms to bond to each other to form the plurality of indium clusters.
18 . The method of claim 14 , wherein the heat-treating of the strain source layer comprises applying heat to the strain source layer in a nitrogen or ammonia-mixed atmosphere.