CN106601885A - Light emitting diode epitaxial structure and growth method thereof - Google Patents

Abstract

The invention discloses a light emitting diode epitaxial structure. An N-type layer is grown on a surface of a substrate, a V-type defect pit is formed on a surface of the N-type layer, an active layer is grown on the N-type layer on which the V-type defect pit is formed, an opening form and opening depth of the V-type defect pit are kept on the active layer, a P-type layer is grown on the active layer, and the V-type defect pit is filled and levelled up. The invention further discloses a growth method of the light emitting diode epitaxial structure. The light emitting diode epitaxial structure is advantaged in that injection efficiency of an electronic and hole-direction active region can be enhanced, uniform distribution of the electronic and hole-direction active region is realized, internal quantum efficiency of the active region can be further enhanced, and light emitting efficiency is improved.

Description

Epitaxial structure and growth method of light-emitting diode

technical field

The invention relates to the technical field of light emitting diodes, in particular to an epitaxial structure of a light emitting diode and a growth method thereof.

Background technique

In the prior art, white LED chips are usually epitaxial on a GaN-based multilayer film structure on a sapphire substrate, and its luminous efficiency = carrier injection efficiency (IE) × internal quantum efficiency (IQE) × light extraction efficiency (EE). Due to the low activation efficiency of Mg doping in P-type GaN, the effective hole concentration is only 1-5E17/cm3, which is far lower than the activation efficiency and effective electron concentration of Si doping in N-type GaN 5E18/cm3-2E19/cm3, Therefore, the hole injection efficiency is the bottleneck of the luminous efficiency. Since the hole injection efficiency is lower than that of electrons, it is easy to cause electron leakage. Generally, only 1-2 QWs (quantum wells) closest to P-type GaN mainly emit light, and other QWs do not emit light or emit light very weakly.

As shown in FIG. 1, in a LED structure disclosed in the prior art, an active layer 20 is grown on an N-type layer 10, and a P-type layer 30 is grown on the active layer 20. The N-type layer 10, the active layer 20 and the P The type layer 30 is a planar structure, and the three-layer structure is parallel to each other. The flow and recombination of holes and electrons are shown in Figure 1a. * indicates electron-hole recombination light emission, ↓ indicates the direction of current/electric field, + indicates the P-type layer, - Represents an N-type layer, as shown in Figure 1a, which has a lower luminous efficiency.

In order to increase the injection of holes and improve the luminous efficiency of light-emitting diodes, an LED structure has been improved in the prior art. The N-type layer 10 is planarly grown with an active layer 20, and a V-shaped defect pit 201 is formed on the active layer 20 to form a V-shaped defect pit. The P-type layer 30 is grown on the concave surface of the active layer 20 of the defect pit 201 , as shown in FIG. 2 . The flow and recombination of holes and electrons are shown in Figure 2a. * indicates electron-hole recombination light emission, ↓ indicates the direction of current/electric field, + indicates the P-type layer, and - indicates the N-type layer. The disadvantage is that the bottom of the V-shaped defect pit is relatively close to the N-type layer, which is easy to cause electric leakage and electron leakage, thereby affecting the photoelectric performance.

Contents of the invention

The object of the present invention is to provide an epitaxial structure of a light emitting diode and a growth method thereof, so as to increase the injection efficiency of electrons and holes into the active region, so that electrons and holes can be uniformly distributed in the active region, thereby increasing the active region. The quantum efficiency in the region improves the luminous efficiency.

To achieve the above object, the solution of the present invention is:

An epitaxial structure of a light-emitting diode, in which an N-type layer is grown on the surface of a substrate, a V-type defect pit is formed on the surface of the N-type layer, an active layer is grown on the N-type layer forming the V-type defect pit, and maintained on the active layer The opening shape and opening depth of the V-type defect pits, grow a P-type layer on the active layer and fill up the V-type defect pits.

Further, the N-type layer includes an unintentionally doped or N-type doped Al _x In _y Ga _(1-xy) N layer, a heavily N-type doped Al _x In _y Ga (1-xy) N layer grown sequentially from bottom to top on the substrate surface. _(1-xy) N layer and heavily N-type doped Al _x In _y Ga _(1-xy) N stress release layer, V-type defect pits are formed in heavily N-type doped Al _x In _y Ga _{(1-xy )} the surface of the N stress release layer; wherein, 0≤x≤1, 0≤y≤1, the N-type doping concentration is 0-1E20cm ^-3 , and the heavy N-type doping concentration is 1E18-1E20cm ^-3 .

Further, the unintentionally doped or N-type doped Al _x In _y Ga _(1-xy) N layer is a single-layer or multi-layer structure, the thickness of each layer is 0-10um, and the N-type doping source is Si, Hf or C element.

Further, the heavily N-type doped Al _x In _y Ga _(1-xy) N layer is a single-layer or multi-layer structure, the thickness of each layer is 0-10um, and the N-type doping source is Si, Hf or C element .

Further, the heavily N-type doped Al _x In _y Ga _(1-xy) N stress release layer is a single-layer or multi-layer structure, the thickness of each layer is 0-10um, and the N-type doping source is Si, Hf or C element.

Further, unintentionally doped or N-type doped Al _x In _y Ga _(1-xy) N layers and heavily N-type doped Al _x In _y Ga _(1-xy) N layers respectively form interconnected through-holes Dislocations, V-type defect pits are formed on the top of threading dislocations, the size of the V-type defect pit opening is 0-1um, and the depth is 0-1um.

Further, the active layer is a single-layer, multi-layer, superlattice or multi-quantum well structure of Al _x In _y Ga _(1-xy) N, where 0≤x≤1, 0≤y≤1, each layer Thickness 0-1um.

Further, the substrate is Al ₂ O ₃ , SiC, Si, GaN or AlN.

Further, the P-type layer is a single-layer, multi-layer, superlattice or multi-quantum well structure of Al _x In _y Ga _(1-xy) N, where 0≤x≤1, 0≤y≤1, each layer The thickness is 0-1um; the P-type doping source is Mg element, and the doping concentration is 1E17-1E21cm ^-3 .

A method for growing an epitaxial structure of a light emitting diode, comprising the following steps:

1. An N-type layer is grown on the surface of the substrate, and V-type defect pits are formed on the surface of the N-type layer;

Second, grow an active layer on the N-type layer forming the V-type defect pit, and maintain the opening shape and opening depth of the V-type defect pit on the active layer;

Third, grow a P-type layer on the active layer and fill up the V-type defect pits.

Further, the following steps are included when growing the N-type layer: an unintentionally doped or N-type doped Al _x In _y Ga _(1-xy) N layer grown sequentially from bottom to top on the substrate surface, heavy N-type doped Al _x In _y Ga _(1-xy) N layer and heavily N-doped Al _x In _y Ga _(1-xy) N stress release layer, V-type defect pits are formed in heavily N-doped Al _x In _y Ga _(1-xy) N stress release layer surface; where, 0≤x≤1,0≤y≤1, N-type doping concentration is 0-1E20cm ^-3 , heavy N-type doping concentration is 1E18-1E20cm ^{-3 3} .

Further, the unintentionally doped or N-type doped Al _x In _y Ga _(1-xy) N layer is a single-layer or multi-layer structure, the thickness of each layer is 0-10um, and the N-type doping source is Si, Hf or C element.

Further, the heavily N-type doped Al _x In _y Ga _(1-xy) N layer is a single-layer or multi-layer structure, the thickness of each layer is 0-10um, and the N-type doping source is Si, Hf or C element .

Further, the heavily N-type doped Al _x In _y Ga _(1-xy) N stress release layer is a single-layer or multi-layer structure, the thickness of each layer is 0-10um, and the N-type doping source is Si, Hf or C element.

Further, unintentionally doped or N-type doped Al _x In _y Ga _(1-xy) N layers and heavily N-type doped Al _x In _y Ga _(1-xy) N layers respectively form interconnected through-holes Dislocations, V-type defect pits are formed on the top of threading dislocations, the size of the V-type defect pit opening is 0-1um, and the depth is 0-1um.

Further, the active layer is a single-layer, multi-layer, superlattice or multi-quantum well structure of Al _x In _y Ga _(1-xy) N, where 0≤x≤1, 0≤y≤1, each layer Thickness 0-1um.

Further, the substrate is Al ₂ O ₃ , SiC, Si, GaN or AlN.

Further, the P-type layer is a single-layer, multi-layer, superlattice or multi-quantum well structure of Al _x In _y Ga _(1-xy) N, where 0≤x≤1, 0≤y≤1, each layer The thickness is 0-1um; the P-type doping source is Mg element, and the doping concentration is 1E17-1E21cm ^-3 .

After adopting the above scheme, V-type defect pits are formed on the surface of the N-type layer of the present invention, an active layer is grown on the N-type layer, and the opening shape and opening depth of the V-type defect pits are maintained on the active layer. The P-type layer is grown and the V-type defect pits are filled up to obtain a spatially folded and parallel P-N junction, which increases the injection efficiency of electrons and holes into the active region, and makes electrons and holes more uniformly distributed in the active region , thereby increasing the quantum efficiency in the active region and improving the luminous efficiency.

Description of drawings

FIG. 1 is a schematic diagram of the epitaxial structure of a light-emitting diode in the prior art;

Figure 1a is a schematic diagram of hole, electron flow and recombination in the epitaxial structure of the light emitting diode in the prior art;

Fig. 2 is a schematic diagram of another light-emitting diode epitaxial structure in the prior art;

Fig. 2a is a schematic diagram of hole, electron flow and recombination in another light-emitting diode epitaxial structure in the prior art;

Fig. 3 is a schematic diagram of the epitaxial structure of the light emitting diode of the present invention;

Fig. 3a is a schematic diagram of hole and electron flow and recombination in the light-emitting diode epitaxial structure of the present invention;

4 to 8 are growth flow diagrams of the present invention.

Label description

N-type layer 10 active layer 20

V-type defect pit 201 P-type layer 30

Substrate 1

Unintentionally doped or N-type doped Al _x In _y Ga _(1-xy) N layer 2

punching dislocation 21

Heavy N-doped Al _x In _y Ga _(1-xy) N layer3

Threading dislocation31 Al _x In _y Ga _(1-xy) N Stress release layer4

V-shaped defect pit 5 active layer 6

P-type layer 7 N-type layer 8 .

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Referring to Figures 4 to 8, a method for growing an epitaxial structure of a light-emitting diode disclosed in the present invention includes the following steps:

One, as shown in FIG. 4 , grow an unintentionally doped or N-type doped Al _x In _y Ga _(1-xy) N layer 2 on the surface of the substrate 1, where 0≤x≤1, 0≤y≤ 1. N-type doping concentration is 0-1E20cm ^-3 . A threading dislocation 21 is formed in the unintentionally doped or N-type doped Al _x In _y Ga _(1-xy) N layer 2 due to stress. Unintentionally doped or N-type doped Al _x In _y Ga _(1-xy) N layer 2 is a single-layer or multi-layer structure, the thickness of each layer is 0-10um, and the N-type doping source is Si, Hf or C elements. The substrate 1 is Al ₂ O ₃ , SiC, Si, GaN or AlN.

Two, as shown in Figure 5, grow heavy N-type doped _{AlxInyGa (} 1- _xy ) on the _AlxInyGa (1- _{xy )} N layer 2 of unintentional doping or N-type doping N layer 3, wherein, 0≤x≤1, 0≤y≤1, heavy N-type doping concentration is 1E18-1E20cm ^-3 . Due to stress, threading dislocations 31 are correspondingly formed in the N-type doped Al _x In _y Ga _(1-xy) N layer 3 . The heavily N-type doped _{AlxInyGa (1-xy) N} layer 3 is a single-layer or multi-layer structure, each layer has a thickness of 0-10um, and the N-type doping source is Si, Hf or C element.

Three, as shown in Figure 6, grow heavily N-type doped _AlxInyGa (1- _{xy )} N stress release layer on heavily N-type doped _AlxInyGa (1- _{xy )} N layer 3 4. Wherein, 0≤x≤1, 0≤y≤1, the heavy N-type doping concentration is 1E18-1E20cm ^-3 . The heavy N-type doped Al _x In _y Ga _(1-xy) N stress release layer 4 is a single-layer or multi-layer structure, the thickness of each layer is 0-10um, and the N-type doping source is Si, Hf or C element. A V-type defect pit 5 is formed on the surface of the heavily N-type doped Al _x In _y Ga _(1-xy) N stress release layer 4, and the V-type defect pit 5 is formed on the top of the threading dislocation 31. The opening size of the V-type defect pit 5 is 0-1um, the depth is 0-1um.

Fourth, as shown in FIG. 7, an active layer 6 is grown on the heavily N-doped _{AlxInyGa (1-xy) N} stress release layer 4, and a V-shaped defect pit 5 is maintained on the active layer 6 opening shape and opening depth. The active layer 6 is a single-layer, multi-layer, superlattice or multi-quantum well structure of Al _x In _y Ga _(1-xy) N, where 0≤x≤1, 0≤y≤1, the thickness of each layer 0-1um.

Fifth, as shown in FIG. 8 , grow a P-type layer 7 on the active layer 6 and fill up the V-type defect pits 5 . The P-type layer 7 is a single-layer, multi-layer, superlattice or multi-quantum well structure of Al _x In _y Ga _(1-xy) N, where 0≤x≤1, 0≤y≤1, the thickness of each layer 0-1um; P-type doping source is Mg element, doping concentration 1E17-1E21cm ^-3 .

As shown in Fig. 3 and Fig. 3a, in the epitaxial structure of the light emitting diode grown by the above method, an N-type layer 8 is grown on the surface of the substrate 1, and V-type defect pits 5 are formed on the surface of the N-type layer 8, and V-type defect pits 5 are formed. The active layer 6 is grown on the N-type layer 8, and the opening shape and opening depth of the V-type defect pit 5 are maintained on the active layer 6, and the P-type layer 7 is grown on the active layer 6 and the V-type defect pit 5 is filled. flat.

The N-type layer 8 includes an unintentionally doped or N-type doped Al _x In _y Ga _(1-xy) N layer 2, a heavily N-type doped Al _x In _y Ga _(1-xy) N layer 3 and heavily N-type doped Al _x In _y Ga _(1-xy) N stress release layer 4, V-type defect pits 5 formed in heavily N-type doped Al _x In _y Ga _(1-xy) N stress release layer 4 surface; wherein, 0≤x≤1, 0≤y≤1, N-type doping concentration is 0-1E20cm ^-3 , heavy N-type doping concentration is 1E18-1E20cm ^-3 .

As shown in Figure 3a, a schematic diagram of the flow and recombination of holes and electrons, * indicates electron-hole recombination light emission, ↓ indicates the direction of current/electric field, + indicates a P-type layer, and - indicates an N-type layer. It can be seen from Figure 3a that the present invention obtains The spatially folded and parallel P-N junction increases the injection efficiency of electrons and holes into the active area, so that electrons and holes are more uniformly distributed in the active area, thereby increasing the quantum efficiency in the active area and improving the luminous efficiency.

The formation of V-shaped defect pits is the result of the release of stress by threading dislocations. For example, if InGaN/GaN multi-quantum wells or superlattice structures are grown on the surface of GaN, the stress will be released at the threading dislocations when the stress accumulates to a certain extent due to the difference in lattice constants. V-shaped defect pits are formed.

The above descriptions are only preferred embodiments of the present invention, and are not limitations on the design of this case. All equivalent changes made according to the key points of the design of this case fall within the scope of protection of this case.

Claims (10)

1. a kind of epitaxial structure of light emitting diode, it is characterised in that：N-type layer is grown in substrate surface, N-type layer surface forms V Type defect is cheated, and active layer is grown in the N-type layer for forming V-type defect hole, and the opening shape in V-type defect hole is kept on active layer State and opening depth, on active layer growing P-type layer and by V-type defect hole fill and lead up.

2. a kind of epitaxial structure of light emitting diode as claimed in claim 1, it is characterised in that：N-type layer is included in substrate table Unintentional doping or the Al of n-type doping that face is grown from the bottom to top successively_xIn_yGa_(1-x-y)What N shell, heavy N-type were adulterated Al_xIn_yGa_(1-x-y)N shell and the Al of heavy N-type doping_xIn_yGa_(1-x-y)N stress release layers, V-type defect hole are formed at heavy N-type doping Al_xIn_yGa_(1-x-y)N Stress Release layer surfaces；Wherein, 0≤x≤1,0≤y≤1, n-type doping concentration are 0-1E20cm^-3, weight N-type doping concentration is 1E18-1E20cm^-3。

3. a kind of epitaxial structure of light emitting diode as claimed in claim 2, it is characterised in that：Unintentional doping or N-type are mixed Miscellaneous Al_xIn_yGa_(1-x-y)N shell is single or multiple lift structure, and each layer of thickness is 0-10um, and n-type doping source is Si, Hf or C Element.

4. a kind of epitaxial structure of light emitting diode as claimed in claim 2, it is characterised in that：Heavy N-type doping Al_xIn_yGa_(1-x-y)N shell is single or multiple lift structure, and each layer of thickness is 0-10um, and n-type doping source is Si, Hf or C element.

5. a kind of epitaxial structure of light emitting diode as claimed in claim 2, it is characterised in that：Heavy N-type doping Al_xIn_yGa_(1-x-y)N stress release layers are single or multiple lift structure, and each layer of thickness is 0-10um, and n-type doping source is Si, Hf Or C element；Unintentional doping or the Al of n-type doping_xIn_yGa_(1-x-y)N shell and the Al of heavy N-type doping_xIn_yGa_(1-x-y)Divide in N shell The break-through dislocation being connected with each other is not formed, V-type defect hole is formed at the top of break-through dislocation, and V-type defect hole openings of sizes is 0- 1um, depth are 0-1um.

6. a kind of epitaxial structure of light emitting diode as claimed in claim 1, it is characterised in that：Active layer is Al_xIn_yGa_(1-x-y)The monolayer of N, multilamellar, superlattices or multi-quantum pit structure, wherein 0≤x≤1,0≤y≤1, each layer of thickness Degree 0-1um；P-type layer is Al_xIn_yGa_(1-x-y)The monolayer of N, multilamellar, superlattices or multi-quantum pit structure, wherein 0≤x≤1,0≤ Y≤1, each layer of thickness is 0-1um；P-type doped source be Mg elements, doping content 1E17-1E21cm^-3；Substrate is Al₂O₃、 SiC, Si, GaN or AlN.

7. a kind of epitaxial structures growth method of light emitting diode, it is characterised in that：Comprise the following steps：

One, N-type layer is grown in substrate surface, N-type layer surface forms V-type defect hole；

Two, active layer is grown in the N-type layer for forming V-type defect hole, and the open shape in V-type defect hole is kept on active layer With opening depth；

Three, on active layer growing P-type layer and by V-type defect hole fill and lead up.

8. the epitaxial structures growth method of a kind of light emitting diode as claimed in claim 7, it is characterised in that：In growth N-type Comprise the following steps during layer：The unintentional doping that grown successively in substrate surface from the bottom to top or n-type doping Al_xIn_yGa_(1-x-y)N shell, the Al of heavy N-type doping_xIn_yGa_(1-x-y)N shell and the Al of heavy N-type doping_xIn_yGa_(1-x-y)N Stress Releases Layer, V-type defect hole are formed at the Al of heavy N-type doping_xIn_yGa_(1-x-y)N Stress Release layer surfaces；Wherein, 0≤x≤1,0≤y≤ 1, n-type doping concentration is 0-1E20cm^-3, heavy N-type doping content is 1E18-1E20cm^-3。

9. the epitaxial structures growth method of a kind of light emitting diode as claimed in claim 8, it is characterised in that：It is unintentional to mix The Al of miscellaneous or n-type doping_xIn_yGa_(1-x-y)N shell is single or multiple lift structure, and each layer of thickness is 0-10um；Heavy N-type doping Al_xIn_yGa_(1-x-y)N shell is single or multiple lift structure, and each layer of thickness is 0-10um；The Al of heavy N-type doping_xIn_yGa_(1-x-y)N Stress release layer is single or multiple lift structure, and each layer of thickness is 0-10um；Unintentional doping or n-type doping Al_xIn_yGa_(1-x-y)N shell and the Al of heavy N-type doping_xIn_yGa_(1-x-y)Form the break-through dislocation being connected with each other in N shell respectively, V-type lacks Pitfall is formed at the top of break-through dislocation, and V-type defect hole openings of sizes is 0-1um, and depth is 0-1um；N-type doping source be Si, Hf or C element.

10. the epitaxial structures growth method of a kind of light emitting diode as claimed in claim 8, it is characterised in that：Active layer is Al_xIn_yGa_(1-x-y)The monolayer of N, multilamellar, superlattices or multi-quantum pit structure, wherein 0≤x≤1,0≤y≤1, each layer of thickness Degree 0-1um；Substrate is Al₂O₃, SiC, Si, GaN or AlN；P-type layer is Al_xIn_yGa_(1-x-y)The monolayer of N, multilamellar, superlattices or many Quantum well structure, wherein 0≤x≤1,0≤y≤1, each layer of thickness is 0-1um；P-type doped source is Mg elements, is adulterated dense Degree 1E17-1E21cm^-3。