WO2020248509A1

WO2020248509A1 - Electric-injection micro-disk resonant cavity light-emitting device and preparation method therefor

Info

Publication number: WO2020248509A1
Application number: PCT/CN2019/119048
Authority: WO
Inventors: 张保平; 梅洋; 许荣彬; 徐欢; 应磊莹; 郑志威
Original assignee: 厦门大学
Priority date: 2019-06-14
Filing date: 2019-11-18
Publication date: 2020-12-17
Also published as: CN110212078A; KR20200143410A; KR102434130B1; CN110212078B

Abstract

The present invention relates to the technical field of photoelectrons and semiconductor lasers, in particular to an electric-injection micro-disk resonant cavity light-emitting device and a preparation method therefor. Disclosed are an electric-injection micro-disk resonant cavity light-emitting device and a preparation method therefor. The electric-injection micro-disk resonant cavity light-emitting device comprises a semiconductor micro-disk, a metal support column and a metal support substrate, wherein the semiconductor micro-disk is supported on the metal support substrate by means of the metal support column, and an edge of the semiconductor micro-disk protrudes out of a side wall of the metal support column to form a suspended structure. The present invention provides a good solution for the problem of current injection of a micro-disk resonant cavity having an edge suspended structure, and compared with other semiconductor support materials such as Si in a conventional micro-disk resonant cavity light-emitting device, the metal support column can better improve a heat dissipation characteristic of the device; and the metal support column and the metal support substrate can be prepared in an electroplating manner, the process is simple, all the preparation processes are compatible with a standard semiconductor preparation process, and the requirement of large-scale photoelectric integration is met.

Description

Electric injection microdisk resonant cavity light emitting device and preparation method thereof

Technical field

The invention belongs to the technical field of optoelectronics and semiconductor lasers, and specifically relates to an electric injection microdisk resonant cavity light emitting device and a preparation method thereof.

Background technique

In recent years, semiconductor micro-resonant cavities are attracting more and more attention because of their strong confinement effect on light. They not only provide a good platform for theoretical research such as quantum electrodynamics, but also have good application prospects in practical applications such as single photon sources, micro-nano lasers, and micro-nano LEDs. The semiconductor microdisk resonant cavity is an optical microcavity system based on the whispering gallery mode, in which light propagates and resonates along the edge of the microdisk due to total reflection. The microdisk resonant cavity has the advantages of simple structure, strong optical confinement, small mode volume, low current operation, etc., and it has a wide range of applications in biosensors and photoelectric integration.

Since the modes in the semiconductor microdisk resonant cavity are mainly limited to the edge of the microdisk, the semiconductor microdisk resonant cavity often has a supporting part in the center of the microdisk to connect to the substrate, and the part near the edge of the microdisk is a suspended structure, which can reduce The optical diffraction loss of the small mode to the substrate has a better restriction on the optical mode in the vertical direction. However, this floating structure brings difficulties to the current injection of the device, and most of the semiconductor microdisk resonators with a floating structure can only work under the condition of an optical pump. Under normal circumstances, the support pillars at the bottom of the semiconductor microdisk resonant cavity are prepared by wet etching the substrate. In order to achieve current injection into the active area of the semiconductor microdisk, the support pillars below the microdisk must be used as current channels. This requires the support pillars and the epitaxial layer in the semiconductor microdisk that directly contacts the support pillars to have good conductivity. It is feasible to prepare electrically implanted microdisk resonators in InP-based semiconductor materials in this way, because high-conductivity InP substrates are easy to obtain and wet etching of InP is easier. In 2012, YHKim et al. prepared an electrically injected microdisk resonator laser with a suspended edge structure in this way. For details, please refer to "Kim Y H, Kwon S H, Lee J M, et al. Graphene-contact electrically driven microdisk lasers[J].Nature communications,2012,3:1123'' and ``Park H G, Kim Y H, Hwang M, et al. Nanolaser generator using graphene electrode and method for manufacturing the same: USPatent 8,908,736 [P]. 2014-12-9", the current is injected into the active area through the support column under the microdisk and the electrode on the upper surface of the microdisk. However, in other semiconductor materials, especially GaN-based semiconductor materials, it is difficult to fabricate electrically injected microdisk cavity light-emitting devices in this way. Taking GaN-based semiconductor materials as an example, GaN is often epitaxially grown on GaN, SiC, and sapphire substrates. Wet etching of these substrates is more difficult, and it is difficult to form a suspended structure, and the epitaxial layer of GaN directly in contact with the substrate is often a low-temperature nucleation layer, with poor crystal quality and high resistivity, making it difficult to serve as a current channel. In recent years, great progress has been made in the epitaxial growth of GaN on Si substrates. The wet etching of Si is relatively easy, so it is easy to prepare microdisk resonators with suspended structures. However, the low-temperature nucleation layer where the microdisk contacts the Si support pillars is still With large resistivity, it is difficult to achieve current injection. In 2004 and 2018, M. Kneissl et al. "Kneissl M, Teepe M, Miyashita N, et al. Current-injection spiral-shaped microcavity disk laser diodes with unidirectional emission[J]. Applied Physics Letters, 2004, 84( 14):2485-2487" and M. Feng et al. "Feng M, He J, Sun Q, et al. Room-temperature electrically pumped InGaN-based microdisk laser grown on Si[J].Optics express,2018,26( 4): "5043-5051" respectively reported electrical injection of GaN-based microdisk resonator lasers, but their semiconductor microdisk is a cylindrical structure, which is directly connected to the substrate and is not suspended. The current flows through the n-GaN on both sides of the microdisk. Enter the microdisk laterally and inject into the active area. Since there is no suspended structure, the diffraction loss of the optical field in the resonant cavity into the substrate is very large. The epitaxial wafer must be specially designed to form a waveguide structure in the horizontal direction to limit the optical field to the vicinity of the active area in the vertical direction. The Q value is low.

Therefore, in view of the above difficulties of electrical injection into the microdisk resonant cavity light emitting device, it is necessary to develop a new electrical injection microdisk resonant cavity light emitting device that can satisfy all semiconductor materials.

Summary of the invention

The purpose of the present invention is to provide an electrically injected microdisk resonant cavity light emitting device and a preparation method thereof to solve the above-mentioned technical problems.

In order to achieve the above objective, the technical solution adopted by the present invention is: an electrically injected microdisk resonant cavity light emitting device, comprising a semiconductor microdisk, a metal support column and a metal support substrate, the semiconductor microdisk is supported on the metal support substrate through the metal support column Above, the edge of the semiconductor microdisk protrudes from the sidewall of the metal supporting column to form a suspended structure.

Further, a current spreading layer is also provided between the semiconductor microdisk and the metal supporting column.

Further, the semiconductor microdisk has a circular structure.

Furthermore, the metal supporting column has a cylindrical structure.

Furthermore, the metal supporting column is aligned with the center of the semiconductor microdisk.

Further, the semiconductor microdisk includes a stacked p-type semiconductor epitaxial layer, an active region, and an n-type semiconductor epitaxial layer in order from bottom to top.

Further, the metal supporting column and the metal supporting substrate are made of copper or aluminum and are integrally formed.

The invention also discloses a preparation method for the above-mentioned electric injection microdisk resonant cavity light-emitting device, which is characterized in that it comprises the following steps:

S1, growing a pin structure semiconductor epitaxial layer on the substrate, and proceed to step S2;

S2, depositing a dielectric film layer with small holes on the outer surface of the semiconductor epitaxial layer, and the small holes penetrate the dielectric film layer to the outer surface of the semiconductor epitaxial layer, and proceed to step S3;

S3, preparing a metal layer on the surface of the dielectric film layer, the metal layer fills the small holes of the dielectric film layer, and step S4 is performed;

S4, remove the substrate, and go to step S5;

S5, etching the semiconductor epitaxial layer to form a semiconductor microdisk, and then proceeding to step S6;

S6, remove the dielectric film layer, and go to step S7;

S7, an electrode is deposited on the surface of the semiconductor microdisk to complete the device preparation.

Further, in step S2, the dielectric film layer is a SiO ₂ dielectric film layer.

Furthermore, in step S1, a pin structure semiconductor epitaxial layer is grown by MOCVD or MBE;

In step S3, electroplating is used to prepare a metal layer on the surface of the dielectric film layer;

In step S5, a semiconductor microdisk is formed by photolithography or dry etching;

In step S6, the dielectric film layer is removed by using wet etching.

The beneficial technical effects of the present invention:

The edge part of the semiconductor microdisk of the present invention is separated from the metal supporting substrate to form a suspended structure, thereby forming a strong restriction on the optical field in the resonant cavity in the vertical direction. The metal supporting column and the metal supporting substrate can simultaneously perform current injection It effectively solves the current injection problem of the microdisk resonator with a suspended edge structure. Compared with other semiconductor support materials and substrates such as Si in traditional microdisk resonator light-emitting devices, the metal support column and the metal support substrate also Can better improve the heat dissipation characteristics of the device.

The present invention can be prepared by electroplating and wet etching processes, can realize the preparation of electric injection microdisk resonant cavity light-emitting devices suitable for any semiconductor material system, all preparation processes are compatible with standard semiconductor preparation processes, and meet the needs of large-scale optoelectronic integration. It has a broad application prospect.

Description of the drawings

In order to more clearly describe the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings needed in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative work, other drawings can be obtained from these drawings.

1 is a cross-sectional view of the structure of an electrically injected microdisk resonant cavity light emitting device according to a specific embodiment of the present invention;

Figure 2 is a flow chart of the preparation method of a specific embodiment of the invention;

Figure 3 is a schematic diagram of the epitaxial wafer structure;

4 is a schematic diagram of depositing a patterned SiO ₂ dielectric film with small holes on the epitaxial wafer;

Figure 5 is a schematic cross-sectional view of the structure of the sample after the electrode for electroplating is evaporated;

6 is a schematic cross-sectional view of the structure of the sample after electroplating the metal supporting substrate;

Figure 7 is a schematic cross-sectional view of the structure after the sample is inverted and the original substrate is removed;

8 is a schematic cross-sectional view of the structure of the sample after etching the microdisk mesa;

Fig. 9 is a schematic cross-sectional view of the structure of the sample after the SiO ₂ dielectric film layer is removed by wet etching;

FIG. 10 is a schematic cross-sectional view of the structure of the sample after the electrode on the microdisk is evaporated.

Detailed ways

To further illustrate the embodiments, the present invention is provided with drawings. These drawings are a part of the disclosure of the present invention, which are mainly used to illustrate the embodiments, and can cooperate with the relevant description in the specification to explain the operation principle of the embodiments. With reference to these contents, those of ordinary skill in the art should be able to understand other possible implementation modes and the advantages of the present invention. The components in the figure are not drawn to scale, and similar component symbols are usually used to indicate similar components.

The present invention will now be further described with reference to the drawings and specific embodiments.

As shown in FIG. 1, an electrically injected microdisk resonant cavity light-emitting device includes a semiconductor microdisk 1, a metal support column 2 and a metal support substrate 3. The semiconductor microdisk 1 is supported on the metal support substrate 3 through the metal support column 2 On the surface, the edge of the semiconductor microdisk 1 protrudes from the sidewalls of the metal support column 2 to form a suspended structure, so that the light field in the resonant cavity of the semiconductor microdisk 1 is reflected in the vertical direction (that is, the direction perpendicular to the metal support substrate 3). Form a strong restriction, the metal support column 2 and the metal support substrate 3 can play the role of current injection at the same time, which solves the current injection problem of the microdisk resonant cavity with a suspended edge structure, and is compared with the traditional microdisk resonator Other semiconductor supporting materials and substrates such as Si in the light-emitting device, the metal supporting column 2 and the metal supporting substrate 3 can also better improve the heat dissipation characteristics of the device.

In this specific embodiment, an upper electrode 81 is further included, and the upper electrode 81 is disposed on the upper surface of the semiconductor microdisk 1 (take the direction of FIG. 1 as a reference). The material of the upper electrode 81 may be Cr, Au, Ni, Ti, or other metal electrode materials with good electrical conductivity, or laminated layers of different metal materials such as Cr/Au, Ni/Au, Ti/Au.

In this embodiment, the semiconductor microdisk 1 preferably has a circular structure, is compact in structure, and is easy to prepare. However, it is not limited thereto. In some embodiments, the semiconductor microdisk 1 may also be triangular, square, hexagonal, or the like.

The semiconductor microdisk 1 includes a stacked p-type semiconductor epitaxial layer 14, an active region 13, and an n-type semiconductor epitaxial layer 12 in order from bottom to top, forming a PIN structure. It can be made of GaN-based, GaAs-based, InP-based and other materials.

In this specific embodiment, the metal supporting column 2 is preferably a cylindrical structure, which is more suitable for the structure of the circular semiconductor microdisk 1. However, it is not limited to this. In some embodiments, the metal support column 2 may also be triangular column shape, hexagonal column shape, or the like. The metal support column 2 is preferably made of copper or aluminum material, which has good electrical and thermal conductivity and low cost. Of course, in other embodiments, it may also be other metal materials with good thermal and electrical conductivity.

The diameter of the semiconductor microdisk 1 is greater than the diameter of the metal support column 2, and the center of the semiconductor microdisk 1 and the metal support column 2 are aligned, that is, the center axis of the semiconductor microdisk 1 coincides with the center axis of the metal support column 2, making the manufacturing process simpler and the structure Stability is better, but not limited to this. In some embodiments, the semiconductor microdisk 1 and the metal support pillar 2 may not be aligned centrally, as long as the edge of the semiconductor microdisk 1 protrudes from the sidewall of the metal support pillar 2 to form a suspended structure.

In this embodiment, the metal supporting substrate 3 is preferably made of copper or aluminum material, which has good electrical and thermal conductivity and low cost. Of course, in other embodiments, it may also be other metal materials with good thermal and electrical conductivity.

In this specific embodiment, the metal supporting column 2 and the metal supporting substrate 3 are integrally formed, the preparation process is simple, and the conductive effect is better.

In some embodiments, a current spreading layer (not shown in the figure) can be selectively deposited between the p-type semiconductor epitaxial layer 14 and the metal support pillar 2 according to the difference in the conductivity of the semiconductor material of the p-type semiconductor epitaxial layer 14. For example, in a GaN-based material system, p-GaN current spreading characteristics are poor, and a current spreading layer such as ITO needs to be deposited, but it can be omitted in GaAs-based and InP-based materials.

As shown in Figure 2, the present invention also discloses a method for manufacturing the above-mentioned electric injection microdisk resonant cavity light-emitting device, which includes the following steps:

S1, growing a pin structure semiconductor epitaxial layer on the substrate, and proceed to step S2.

Specifically, as shown in FIG. 3, the pin structure semiconductor epitaxial layer is grown on the substrate 11 using the MOCVD or MBE method, specifically: an n-type semiconductor epitaxial layer 12, an active region 13, and a p The type semiconductor epitaxial layer 14 forms an epitaxial wafer. The material of the substrate 11 is selected according to different semiconductor material systems. For example, GaN-based materials generally use GaN, sapphire, Si, SiC and other substrates, GaAs-based materials are generally grown using GaAs substrates, and InP-based materials are grown using InP substrates. .

According to the conductivity difference of the material of different p-type semiconductor epitaxial layer 14, a current spreading layer such as ITO can be selectively prepared on the surface of p-type semiconductor epitaxial layer 14. For example, in the GaN-based material system, the current spreading characteristics of p-GaN are poor, and a current spreading layer such as ITO is deposited on the surface of the p-type semiconductor epitaxial layer 14, but it can be omitted in GaAs-based and InP-based materials. In this specific embodiment, no current spreading layer is prepared.

S2, depositing a dielectric film layer with small holes on the outer surface of the semiconductor epitaxial layer, the small holes penetrate the dielectric film layer to the outer surface of the semiconductor epitaxial layer, and proceed to step S3.

Specifically, as shown in FIG. 4, a SiO ₂ dielectric film layer 21 is prepared on the upper surface of the p-type semiconductor epitaxial layer 14 (Of course, in other embodiments, the dielectric film layer 21 may also be SiN, TiO ₂ , Ta ₂ O ₅ and other dielectric films that are easy to be wet-etched), and use photolithography and other processes to pattern the SiO ₂ dielectric film 21 into small holes 211, which penetrate through the dielectric film 21 to the outer side of the p-type semiconductor epitaxial layer 14. surface. The thickness of the SiO ₂ dielectric film 21 can be several hundreds of nanometers to several micrometers, and the diameter of the small holes 211 can be several micrometers to several hundreds of micrometers.

S3, preparing a metal layer on the surface of the dielectric film layer, the metal layer fills the small holes of the dielectric film layer, and step S4 is entered.

Specifically, as shown in FIG. 5, a whole metal electrode layer 31 is prepared on the surface of the SiO ₂ dielectric film layer 21 and the sidewall and bottom surface of the small hole 211 by sputtering or evaporation, etc., as the electrode for the subsequent electroplating process. , While retaining the shape of the small hole 211 in step S2. The material of the metal electrode layer 31 may be Cr, Au, Ni, Ti, or other metal electrode materials with good electrical conductivity, or laminated layers of different metal materials such as Cr/Au, Ni/Au, and Ti/Au.

Next, as shown in FIG. 6, the metal layer 41 is electroplated on the upper surface of the metal electrode layer 31 by an electroplating method. The thickness of the metal layer 41 can be tens to hundreds of microns. The material of the metal layer 41 can be copper, aluminum or other thermally conductive materials. Metal material with good conductivity. The metal layer 41 fills up the small holes 211.

S4, the substrate is removed, and step S5 is entered.

Specifically, as shown in FIG. 7, the sample formed in step S3 is turned upside down, and the substrate 11 is removed by peeling, polishing or etching.

S5, the semiconductor epitaxial layer is etched to form a semiconductor microdisk, and step S6 is performed.

Specifically, as shown in FIG. 8, the semiconductor microdisk 1 is prepared by using methods such as photolithography and etching, and the etched stop layer is the SiO ₂ dielectric film layer 21, so that the SiO ₂ dielectric film layer 21 is exposed on the surface. The diameter of the semiconductor microdisk 1 can be several to several hundreds of microns, but is larger than the diameter of the small hole 211.

S6, removing the dielectric film layer, and proceed to step S7.

Specifically, as shown, is removed using wet etching manner. 9 SiO ₂ dielectric film 21, a semiconductor microdisk SiO ₂ below will be undercut inwardly, so that the edge portion of the semiconductor micro-aperture plate 211 1 A suspended structure with an air gap is formed between the outer metal layer 41 and the metal electrode layer 31 (which constitutes the metal supporting substrate 3), and the metal layer 41 and the metal electrode layer 31 inside the small hole 211 become the supporting structure of the semiconductor microdisk 1 At the same time, it acts as a current channel in current injection, that is, as a metal supporting column 2.

Specifically, as shown in FIG. 10, an upper electrode 81 is prepared on the upper surface of the n-type semiconductor epitaxial layer 12 by sputtering or evaporation. The material of the upper electrode 81 can be Cr, Au, Ni, Ti or other good conductivity. The metal electrode material or laminated layers of different metal materials such as Cr/Au, Ni/Au, Ti/Au are formed to complete the device preparation.

Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, those skilled in the art should understand that the present invention can be modified in form and detail without departing from the spirit and scope of the present invention as defined by the appended claims. Various changes are within the protection scope of the present invention.

Claims

An electrical injection microdisk resonant cavity light emitting device, which is characterized in that it comprises a semiconductor microdisk, a metal support column and a metal support substrate. The semiconductor microdisk is supported on the metal support substrate through the metal support column, and the edge of the semiconductor microdisk protrudes A suspended structure is formed on the side wall of the metal support column.
The electrical injection microdisk resonant cavity light emitting device according to claim 1, wherein a current spreading layer is further provided between the semiconductor microdisk and the metal supporting column.
The electrical injection microdisk resonant cavity light-emitting device according to claim 1, wherein the semiconductor microdisk has a circular structure.
The electrically injected microdisk resonant cavity light emitting device according to claim 3, wherein the metal supporting column is a cylindrical structure.
The electrically injected microdisk resonant cavity light emitting device according to claim 4, wherein the metal supporting column is aligned with the center of the semiconductor microdisk.
The electrical injection microdisk resonant cavity light-emitting device according to claim 1, wherein the semiconductor microdisk includes a stacked p-type semiconductor epitaxial layer, an active region and an n-type semiconductor epitaxial layer in order from bottom to top.
The electrical injection microdisk resonant cavity light-emitting device according to claim 1, wherein the metal supporting column and the metal supporting substrate are made of copper material and are integrally formed.
The electric injection microdisk resonant cavity light-emitting device according to claim 1, wherein the metal supporting column and the metal supporting substrate are made of aluminum material and are integrally formed.
A manufacturing method for the electrical injection microdisk resonant cavity light-emitting device according to claim 1, characterized in that it comprises the following steps:

S1, growing a pin structure semiconductor epitaxial layer on the substrate, and proceed to step S2;

S2, depositing a dielectric film layer with small holes on the outer surface of the semiconductor epitaxial layer, and the small holes penetrate the dielectric film to the outer surface of the semiconductor epitaxial layer, and proceed to step S3;

S3, preparing a metal layer on the surface of the dielectric film layer, the metal layer fills the small holes of the dielectric film layer, and step S4 is performed;

S4, remove the substrate, and go to step S5;

S5, etching the semiconductor epitaxial layer to form a semiconductor microdisk, and then proceeding to step S6;

S6, remove the dielectric film layer, and go to step S7;

S7, an electrode is deposited on the surface of the semiconductor microdisk to complete the device preparation.
The method for manufacturing an electrically injected microdisk resonant cavity light-emitting device according to claim 9, characterized in that: in step S2, the dielectric film layer is a SiO 2 dielectric film layer.
The method for manufacturing an electrically implanted microdisk resonant cavity light-emitting device according to claim 9, characterized in that: in step S1, a pin structure semiconductor epitaxial layer is grown by MOCVD.
The method for manufacturing an electrically injected microdisk resonant cavity light emitting device according to claim 9, wherein in step S1, an MBE method is used to grow a pin structure semiconductor epitaxial layer.
The method for manufacturing an electrically injected microdisk resonant cavity light-emitting device according to claim 9, characterized in that: in step S3, electroplating is used to prepare a metal layer on the surface of the dielectric film layer;
The method for manufacturing an electrically injected microdisk resonant cavity light-emitting device according to claim 9, characterized in that: in step S5, photolithography or dry etching is used to form a semiconductor microdisk;
The method for manufacturing an electrically injected microdisk resonant cavity light-emitting device according to claim 9, wherein in step S6, the dielectric film layer is removed by wet etching.