LIGHT EMITTING DIODE
A light emitting diode includes a substrate, an n-type semiconductor layer, a p-type semiconductor layer, an active layer, a first electrode, and a second electrode. The n-type semiconductor layer is located between the substrate and the p-type semiconductor layer. The active layer is located between the n-type semiconductor layer and the p-type semiconductor layer. The wavelength of light emitted by the active layer is λ, and 222 nm≦λ≦405 nm. The active layer includes i quantum barrier layers and (i−1) quantum wells, each quantum well is located between any two quantum barrier layers, and i is an integer greater than or equal to 2. The thickness of each of the quantum barrier layers counting from the p-type semiconductor layer is T 1 to T i , and T 1 is greater than T 2 and T 3 , or T 1 =T 2 >T 3 , or T 1 >T 2 >T 3 .
1 . A light emitting diode comprising:
a substrate;
an n-type semiconductor layer and a p-type semiconductor layer, wherein the n-type semiconductor layer is located between the substrate and the p-type semiconductor layer;
an active layer located between the n-type semiconductor layer and the p-type semiconductor layer, wherein a wavelength of light emitted by the active layer is λ, 222 nm≦λ≦405 nm, the active layer includes i quantum barrier layers and (i−1) quantum wells, each of the quantum wells is located between any two of the quantum barrier layers, i is a natural number greater than or equal to 2, a thickness of each of the quantum barrier layers, counting from the p-type semiconductor layer, is T 1 , T 2 , T 3 . . . , and T i in sequence, and T 1 is greater than T 2 and T 3 ; and
a first electrode and a second electrode, wherein the first electrode is located on a portion of the n-type semiconductor layer, and the second electrode is located on a portion of the p-type semiconductor layer.
2 . The light emitting diode as recited in claim 1 , wherein T 2 ≧T 3 .
3 . The light emitting diode as recited in claim 1 , wherein an i th quantum barrier layer of the i quantum barrier layers closest to the n-type semiconductor layer has the smallest thickness T i .
4 . The light emitting diode as recited in claim 1 , wherein an n-type dopant is doped into at least k quantum barrier layers of the i quantum barrier layers, k is a natural number greater than or equal to 1, k≧i/2 when i is an even number, and k≧(i−1)/2 when i is an odd number.
5 . The light emitting diode as recited in claim 4 , wherein a dopant concentration in the k quantum barrier layers is from 5×10 17 /cm 3 to 1×10 19 /cm 3 .
6 . The light emitting diode as recited in claim 1 , wherein a first quantum barrier layer of the i quantum barrier layers closest to the p-type semiconductor layer has the thickness T 1 ranging from 6 nm to 15 nm.
7 . The light emitting diode as recited in claim 1 , wherein a material of the quantum barrier layers comprises Al x In y Ga 1-x-y N, 0≦x≦1, 0≦y≦0.3, and x+y≦1.
8 . The light emitting diode as recited in claim 1 , wherein a material of the quantum wells comprises Al m In n Ga 1-m-n N, 0≦m≦1, 0≦n≦0.5, m+n≦1, x>m, and n≧y.
9 . A light emitting diode comprising:
a substrate;
an n-type semiconductor layer and a p-type semiconductor layer, wherein the n-type semiconductor layer is located between the substrate and the p-type semiconductor layer;
an active layer located between the n-type semiconductor layer and the p-type semiconductor layer, wherein a wavelength of light emitted by the active layer is λ, 222 nm≦λ≦405 nm, the active layer includes i quantum barrier layers and (i−1) quantum wells, each of the quantum wells is located between any two of the quantum barrier layers, i is a natural number greater than or equal to 2, a thickness of each of the quantum barrier layers, counting from the p-type semiconductor layer, is T 1 , T 2 , T 3 . . . , and T i in sequence, and T 1 =T 2 >T 3 ; and
a first electrode and a second electrode, wherein the first electrode is located on a portion of the n-type semiconductor layer, and the second electrode is located on a portion of the p-type semiconductor layer.
10 . The light emitting diode as recited in claim 9 , wherein an i th quantum barrier layer of the i quantum barrier layers closest to the n-type semiconductor layer has the smallest thickness T i .
11 . The light emitting diode as recited in claim 9 , wherein an n-type dopant is doped into at least k quantum barrier layers of the i quantum barrier layers, k is a natural number greater than or equal to 1, k≧i/2 when i is an even number, and k≧(i−1)/2 when i is an odd number.
12 . The light emitting diode as recited in claim 11 , wherein a dopant concentration in the k quantum barrier layers is from 5×10 17 /cm 3 to 1×10 19 /cm 3 .
13 . The light emitting diode as recited in claim 9 , wherein a first quantum barrier layer of the i quantum barrier layers closest to the p-type semiconductor layer has the thickness T 1 ranging from about 6 nm to about 15 nm.
14 . The light emitting diode as recited in claim 9 , wherein a material of the quantum barrier layers comprises Al x In y Ga 1-x-y N, 0≦x≦1, 0≦y≦0.3, and x+y≦1.
15 . The light emitting diode as recited in claim 9 , wherein a material of the quantum wells comprises Al m In n Ga 1-m-n N, 0≦m≦1, 0≦n≦0.5, m+n≦1, x>m, and n≧y.