CN212434643U

CN212434643U - Deep ultraviolet LED epitaxial wafer capable of improving N-type ohmic contact

Info

Publication number: CN212434643U
Application number: CN202020265559.8U
Authority: CN
Inventors: 崔志勇; 张晓娜; 张向鹏
Original assignee: Shanxi Zhongke Advanced Ultraviolet Optoelectronics Technology Co ltd
Current assignee: Shanxi Zhongke Advanced Ultraviolet Optoelectronics Technology Co ltd
Priority date: 2020-03-06
Filing date: 2020-03-06
Publication date: 2021-01-29
Anticipated expiration: 2030-03-06

Abstract

The patent discloses a can improve dark ultraviolet LED epitaxial wafer of N type ohmic contact, the epitaxial wafer includes: a substrate; an AlN/AlGaN superlattice stress buffer layer formed on the substrate; the N-pole semiconductor layer comprises a first N-AlGaN layer, an N-GaN layer and a second N-AlGaN layer; the first N-AlGaN layer, the N-GaN layer and the second N-AlGaN layer are sequentially arranged from the superlattice stress buffer layer to the top. The ohmic contact of the N pole of the deep ultraviolet LED epitaxial wafer can be effectively improved through the N pole design of the structure.

Description

Deep ultraviolet LED epitaxial wafer capable of improving N-type ohmic contact

Technical Field

This patent belongs to semiconductor technical field, concretely relates to can improve dark ultraviolet LED epitaxial wafer of N type ohmic contact.

Background

In the prior art, as shown in fig. 1, an epitaxial wafer of a deep ultraviolet LED chip includes an aluminum nitride template layer 101, an AlN/AlGaN superlattice stress buffer layer 102, an N-type aluminum gallium nitride layer 103, a multi-quantum hydrazine structure layer 104, an electron blocking layer 105, and a P-type hole conducting layer 106, which are sequentially formed on a substrate 100. For the epitaxial wafer, for the high Al component N-AlGaN layer, the energy level defect increases progressively along with the Al component, so that the ionization energy of a Si donor is increased, the mobility is reduced, and the electric conductivity of the high Al component N-AlGaN is relatively poor; on the other hand, the small electron affinity leads to a higher schottky barrier at the gold-semi (metal-semiconductor) interface and poorer ohmic contact characteristics, and requires strict optimization of both the metal electrode structure and the alloy annealing conditions. Both aspects limit the availability of low resistance ohmic contacts and keep the chip voltage high.

Disclosure of Invention

This patent is just proposed based on the above-mentioned demand of prior art, and the technical problem that this patent will be solved provides a dark ultraviolet LED epitaxial wafer that can improve N type ohmic contact. Effectively improve ohmic contact.

In order to solve the technical problem, the technical scheme provided by the patent comprises:

a deep ultraviolet LED epitaxial wafer capable of improving N-type ohmic contact is characterized by comprising:

a substrate;

an AlN/AlGaN superlattice stress buffer layer formed on the substrate;

the N-pole semiconductor layer comprises a first N-AlGaN layer, an N-GaN layer and a second N-AlGaN layer; the first N-AlGaN layer, the N-GaN layer and the second N-AlGaN layer are sequentially arranged from the superlattice stress buffer layer to the top.

Preferably, an aluminum nitride template layer is formed between the substrate and the AlN/AlGaN superlattice stress buffer layer.

Preferably, a multiple quantum hydrazine structure layer is formed on the second N-AlGaN layer.

Preferably, a P-type AlGaN electron blocking layer is sequentially formed on the multi-quantum hydrazine structure layer; and forming a P-type GaN hole conduction layer on the P-type AlGaN electron blocking layer.

And

a method for improving N-type ohmic contact of a deep ultraviolet LED epitaxial wafer is used for manufacturing the deep ultraviolet LED epitaxial wafer; the first N-AlGaN layer, the N-GaN layer and the second N-AlGaN layer are sequentially formed from the superlattice stress buffer layer to the top.

By adopting the technical scheme, for the high Al component N-AlGaN, the energy level defect increases with the Al component, so that the ionization energy of a Si donor is increased, the mobility is reduced, and the electric conductivity of the high Al component N-AlGaN is relatively poor; on the other hand, the small electron affinity leads to a higher schottky barrier at the gold-half interface and poorer ohmic contact characteristics, and requires strict optimization of the metal electrode structure and the alloy annealing conditions. The two aspects limit the acquisition of low-resistance ohmic contact, but the structure of the invention is provided with an N-type gallium nitride layer, the technology of N-GaN ohmic contact is mature, and the specific contact resistivity obtained reaches 10^-6～10^-7Ω.cm²And the magnitude is high, so that the N-type ohmic contact is effectively improved.

Drawings

FIG. 1 is a schematic diagram of a deep ultraviolet LED epitaxial wafer in the prior art;

fig. 2 is a schematic diagram of a deep ultraviolet LED epitaxial wafer in the embodiment of the present invention.

Detailed Description

The technical solution described in this patent includes various embodiments and modifications made on the various embodiments. In the present embodiment, these technical solutions are exemplarily set forth by way of the drawings so that the inventive concept, technical features, effects of the technical features, and the like of the present patent become more apparent through the description of the present embodiment. It should be noted, however, that the scope of protection of the patent should obviously not be limited to what is described in the examples, but can be implemented in various ways under the inventive concept of the patent.

In the description of the present embodiment, attention is paid to the following reading references in order to be able to accurately understand the meaning of the words in the present embodiment:

first, in the drawings of the present patent, the same or corresponding elements will be denoted by the same reference numerals. Therefore, the explanation of the reference numerals or names of the elements, etc., which have been presented before may not be repeated later. Also, in the present embodiment, if the terms "first", "second", etc. are used to modify various elements or elements, the terms "first", "second", etc. do not denote any order but merely distinguish the elements or elements from one another. Furthermore, the singular forms "a", "an" and "the" do not refer to only the singular but also the plural unless the context clearly dictates otherwise.

Further, the inclusion or inclusion should be understood to be an open description that does not exclude the presence of other elements on the basis of the elements already described; further, when a layer, region or component is referred to as being "formed on", "disposed on" another layer, region or component, the layer, region or component may be directly or indirectly formed on the other layer, region or component, and similarly, when a relationship between two elements is expressed using terms such as connection, connection or the like, it may be either directly or indirectly connected without particular limitation. The term "and/or" connects two elements in a relational or an inclusive relationship.

In addition, in order to explain the technical solution of the present patent, the sizes of the elements described in the drawings of the present patent do not represent the dimensional proportional relationship of the actual elements, and the elements may be enlarged or reduced for convenience of expression in the present patent.

Example one

The embodiment provides a deep ultraviolet LED epitaxial wafer. Wherein, the deep ultraviolet LED is a light emitting diode with the light emitting central wavelength of less than 300 nm. Various suitable materials may be used to achieve the above-described wavelength emission, one or more of which are presented in this detailed description by way of example only, although other material and structure substitutions will be apparent to those skilled in the art in light of the materials and structures presented in this detailed description. The epitaxial layer refers to a part formed by growing on the substrate in the manufacture of the LED chip, and the corresponding layers/structures may be added or reduced according to specific needs in the present embodiment.

In the present embodiment, the main focus is on the improvement of the ohmic contact to the deep ultraviolet LED epitaxial wafer. But the improvement is based on deep ultraviolet LED epitaxial wafers.

As shown in fig. 2, the deep ultraviolet LED epitaxial wafer in this embodiment includes an aluminum nitride template layer 101, an AlN/AlGaN superlattice stress buffer layer 102, a first N-AlGaN layer 1031, an N-GaN layer 1032, a second N-AlGaN layer 1033, a multi-quantum hydrazine structure layer 104, an electron blocking layer 105, and a P-type hole conducting layer 106, which are sequentially formed on a substrate 100.

Substrate 100

In this particular embodiment, the substrate comprises Si, SiC, sapphire, or the like. The substrate serves as a base for the LED epitaxial layers on which the various LED epitaxial layers are formed.

Aluminum nitride template layer 101

For a deep ultraviolet LED chip, a currently used semiconductor material is aluminum gallium nitride, and in order to prepare high-quality aluminum gallium nitride, an aluminum nitride template layer is usually formed on a substrate to improve the quality of aluminum gallium nitride growth. It may therefore be preferable to provide an aluminum nitride template layer on the substrate so that subsequent aluminum gallium nitride can be grown with high quality.

A process for preparing template layer of aluminium nitride includes such steps as magnetically controlled sputtering to deposit a nucleating layer of aluminium nitride (15-30 nm), and vapor deposition of organic metal compound or vapor phase epitaxy of hydride to epitaxially grow an epitaxial layer of aluminium nitride on said nucleating layer.

AlN/AlGaN superlattice stress buffer layer 102

The AlN/AlGaN superlattice is formed by periodically and alternately laminating AlN layers and AlGaN layers which appear in pairs, and the stress control in the epitaxial growth process of the LED chip is realized by changing the number of each layer of the AlN/AlGaN superlattice so as to improve the production quality of related layers of the LED chip.

A first N-AlGaN layer 1031, an N-GaN layer 1032, and a second N-AlGaN layer 1033

The positions of the first N-AlGaN layer 1031, the N-GaN layer 1032 and the second N-AlGaN layer 1033 in this embodiment are shown in fig. 2. The three layers are arranged from the superlattice stress buffer layer to the upper part in sequence.

The first N-AlGaN layer 1031, the N-GaN layer 1032, and the second N-AlGaN layer 1033 are used as N-poles on the semiconductor epitaxial wafer.

In the prior art, as shown in FIG. 1, the N-AlGaN layer 103 was also used as the N-pole, but the growth of a high Al composition N-AlGaN1 epitaxial layer on the AlN/AlGaN superlattice stress buffer layer was continued; for the high Al component N-AlGaN, the energy level defect increases with the Al component, so that the ionization energy of the Si donor is increased, the mobility is reduced, and the electric conductivity of the high Al component N-AlGaN is relatively poor; on the other hand, the small electron affinity leads to a higher schottky barrier at the gold-half interface and poorer ohmic contact characteristics, and requires strict optimization of the metal electrode structure and the alloy annealing conditions. Both aspects limit the availability of low resistance ohmic contacts and keep the chip voltage high.

In this embodiment, the first N-AlGaN1 epitaxial layer of high Al composition continues to grow on the AlN/AlGaN superlattice stress buffer layer because of the deep ultraviolet light to be emitted. Then forming an N-GaN epitaxial layer with Al component gradually changed into 0 on the first N-AlGaN1 epitaxial layer with high Al component; the specific contact resistivity of N-GaN ohmic contact reaches 10^-6～10^-7Ω.cm²The magnitude is high, and N-type ohmic contact is effectively improved; then growing a second N-AlGaN epitaxial layer with high Al component, of which the Al component is gradually changed from 0, on the N-GaN epitaxial layer 103; the second N-AlGaN epitaxial layer has the same Al composition as the first N-AlGaN epitaxial layer.

Through the sandwich structure, on one hand, the function of an N pole in the deep ultraviolet LED epitaxial wafer can be guaranteed to be effectively completed, and on the other hand, ohmic contact of the N pole is improved through N-GaN.

Multiple quantum hydrazine structure layer 104

The multiple quantum well structure layer (MQW)104 is formed on the second NAlGaN epitaxial layer; the multi-quantum hydrazine structure emits light with peak wavelength in a desired UV region by adjusting the molar composition ratio of Al and Ga metal organic sources; the multi-quantum hydrazine structure layer 104 can be implemented using any suitable materials and structures known in the art.

Electron blocking layer 105 and P-type hole conducting layer 106

Forming a P-type AlGaN electron blocking layer on the multi-quantum hydrazine structure (MQW); and forming a P-type GaN hole conduction layer on the P-type AlGaN electron blocking layer.

The electron blocking layer 105 and the P-type hole conducting layer 106 form a P-pole structure of the epitaxial layer of the deep ultraviolet LED.

Example two

The embodiment relates to a manufacturing method of a deep ultraviolet LED epitaxial wafer, which is used for manufacturing the deep ultraviolet LED epitaxial wafer in the first embodiment. Wherein a first N-AlGaN layer 1031, an N-GaN layer 1032 and a second N-AlGaN layer 1033 are sequentially formed by an N-pole MOCVD method. The remaining layers may be omitted or at least partially replaced as required by the production and actual performance of the chip.

The above are only embodiments of the patent, and all modifications and substitutions that can be made to the patent under the inventive concept of this patent are intended to be included within the scope of the patent.

Claims

1. A deep ultraviolet LED epitaxial wafer capable of improving N-type ohmic contact is characterized by comprising:

a substrate;

an AlN/AlGaN superlattice stress buffer layer formed on the substrate;

2. The deep ultraviolet LED epitaxial wafer capable of improving N-type ohmic contact is characterized in that an aluminum nitride template layer is formed between the substrate and the AlN/AlGaN superlattice stress buffer layer.

3. The deep ultraviolet LED epitaxial wafer capable of improving the N-type ohmic contact is characterized in that a multi-quantum hydrazine structure layer is formed on the second N-AlGaN layer.

4. The deep ultraviolet LED epitaxial wafer capable of improving the N-type ohmic contact is characterized in that a P-type AlGaN electron blocking layer is sequentially formed on a multi-quantum hydrazine structure layer; and forming a P-type GaN hole conduction layer on the P-type AlGaN electron blocking layer.