Light emitting diode and method for fabricating same
View Patent ↗An AlGaInP based light emitting diode is provided with a distributed Bragg reflector comprising a combination of an AlGaAs layer and an AlInP layer, each having a film thickness determined by following formulas (1) to (3): t 1 ={λ 0 /(4× n 1 )}×α (1), t 2 ={λ 0 /(4× n 2 )}×(2−α) (2), and 0.5<α<0.9 (3) wherein t 1 is a film thickness [nm] of the AlGaAs layer, t 2 is a film thickness [nm] of the AlInP layer, λ 0 is a wavelength [nm] of a light to be reflected, n 1 is a refractive index of the AlGaAs layer to the wavelength of the light to be reflected, and n 2 is a refractive index of the AlInP layer to the wavelength of the light to be reflected.
1. A light emitting diode, comprising:
a first conductivity type substrate;
a first conductivity type distributed Bragg reflector comprising a multi-layered film which is made by alternately layering a high refractive index film comprising an AlGaAs layer comprising Al x Ga l-x As wherein an Al mixed crystal ratio x is 0<x<0.6, and a low refractive index film comprising an AlInP layer; and
a light emitting part comprising an active layer sandwiched between a first conductivity cladding layer and a second conductivity cladding layer, wherein:
a film thickness of each of the AlGaAs layer and AlInP layer making up the first conductivity type distributed Bragg reflector is determined by following formulas (1) to (3):
t 1 ={λ 0 /(4× n 1 )}×α (1),
t 2 ={λ 0 /(4× n 2 )}×(2−α) (2), and
0.5<α<0.9 (3)
wherein t 1 is a film thickness [nm] of the AlGaAs layer, t 2 is a film thickness [nm] of the AlInP layer, λ 0 is a wavelength [nm] of a light to be reflected by the Bragg reflector, n 1 is a refractive index of the AlGaAs layer to the wavelength of the light to be reflected by the Bragg reflector, and n 2 is a refractive index of the AlInP layer to the wavelength of the light to be reflected by the Bragg reflector.
2. The light emitting diode, according to claim 1 , wherein:
the first conductivity type distributed Bragg reflector is interposed between the first conductivity cladding layer and the first conductivity type substrate.
3. The light emitting diode, according to claim 1 , further comprising:
a second conductivity type current dispersion layer grown on the light emitting part.
4. The light emitting diode, according to claim 1 , wherein:
the first conductivity type substrate is composed of GaAs, and the light emitting part is composed of AlGaInP or GaInP.
5. The light emitting diode, according to claim 1 , further comprising:
a surface electrode provided as an uppermost layer; and
a backside electrode provided on a backside surface of the first conductivity type substrate.
6. The light emitting diode, according to claim 1 , wherein the light emitting diode is part of a lighting device or a display.
7. The light emitting diode, according to claim 5 , wherein the surface electrode comprises a circular partial electrode.
8. The light emitting diode, according to claim 5 , wherein the backside electrode comprises an n-side metal electrode.