Vertical group III-nitride light emitting device and method for manufacturing the same
View Patent ↗A vertical group III-nitride light emitting device and a manufacturing method thereof are provided. The light emitting device comprises: a conductive substrate; a p-type clad layer stacked on the conductive substrate; an active layer stacked on the p-type clad layer; an n-doped Al x Ga y In 1-x-y N layer stacked on the active layer; an undoped GaN layer stacked on the n-doped layer; and an n-electrode formed on the undoped GaN layer. The undoped GaN layer has a rough pattern formed on a top surface thereof.
1. A method for manufacturing a vertical group III-nitride light emitting device comprising steps of:
(i) preparing a basic substrate having a rough pattern formed on a top surface thereof;
(ii) forming an n-type clad layer, an active layer and a p-type clad layer sequentially on the basic substrate, the clad layers and the active layer having compositions expressed by Al x Ga y In 1-x-y N, where 0≦x≦1, 0≦y≦1, and 0≦x+y≦1;
(iii) forming a conductive substrate on the p-type clad layer;
(iv) removing the basic substrate so as to expose a rough pattern formed on a bottom surface of the n-type clad layer; and
(v) forming an n-electrode on a partial area of the exposed bottom surface of the n-type clad layer,
wherein the basic substrate consists of a single material, the n-type clad layer is grown in direct, physical contact with a top surface of the basic substrate, and at least a part of the n-type clad layer is grown in an area of the top surface of the basic substrate in which the rough pattern is not formed.
2. The method according to claim 1 , wherein the basic substrate comprises one selected from a group consisting of sapphire, SiC, GaN and AlN.
3. The method according to claim 1 , wherein the step (iii) comprises bonding the conductive substrate to the p-clad layer via a conductive adhesive layer.
4. The method according to claim 1 , wherein the step (iii) comprises forming the conductive substrate on the p-type clad layer via plating, deposition or sputtering.
5. The method according to claim 1 , further comprising forming a reflective layer on the p-type clad layer between the step (ii) and the step (iii).
6. The method according to claim 5 , wherein the reflective layer comprises one selected from a group consisting of a CuInO 2 /Ag layer, a CuInO 2 /Al layer and an Ni/Ag/Pt layer.
7. The method according to claim 1 , further comprising forming a transparent electrode layer on the n-type clad layer after the step (iv).
8. The method according to claim 1 , wherein the rough pattern formed on the basic substrate comprises convexes or concaves which are spaced from each other in the range of 20 nm to 100 μm, and each have a width and a height of 20 nm to 100 μm, respectively.
9. The method according to claim 1 , wherein the rough pattern formed on the basic substrate comprises convexes or concaves which are spaced from each other in the range of 200 nm to 3 μm, and each have a width and a height of 200 nm to 3 μm, respectively.
10. The method according to claim 1 , wherein the step (i) is conducted such that the rough pattern has a sectional shape of hemisphere, rectangle or serration.
11. The method according to claim 1 , wherein in step (i), the rough pattern is not formed on a top surface area of the basic substrate corresponding to the n-electrode.
12. The method according to claim 1 , wherein step (ii) comprises:
forming an undoped GaN layer on the basic substrate; and
forming an n-doped layer on the undoped GaN layer, the n-doped layer having a composition expressed by Al x Ga y In 1-x-y N, where 0≦x≦1, 0≦y≦1, and 0≦x+y≦1.