CN111048993A - Micro-disk laser and preparation method thereof - Google Patents

Abstract

The invention discloses a micro-disk laser, which comprises a substrate; the optical microcavity unit is arranged on the substrate and is provided with a disc-shaped microcavity; the electric connection unit is used for injecting current into the optical microcavity unit; the flattening unit coats the substrate, the electric connection unit and the optical microcavity unit, a continuous plane is formed on one side of the electric connection unit opposite to the optical microcavity unit, and the electric connection unit is attached to the continuous plane; the first electrode is arranged on the continuous plane and is in contact connection with the electric connection unit. Through setting up the first electrode on the continuous plane of planarization unit, need not strictly restrict first electrode size, can set up the first electrode that has large tracts of land, be favorable to reducing the preparation degree of difficulty, the cost and the device internal resistance of device, promote device heat dispersion, be suitable for the industrialization volume production of little dish laser instrument. The invention discloses a preparation method of a micro-disk laser, which is simple to operate, high in preparation efficiency and suitable for preparing the micro-disk laser with reduced cost and improved performance.

Description

Micro-disk laser and preparation method thereof

Technical Field

The invention relates to the technical field of semiconductor lasers, in particular to a micro-disk laser and a preparation method thereof.

Background

The microcavity laser is a laser with a resonant cavity with a geometrical dimension close to a wavelength or a sub-wavelength in at least one dimension, and the device has wide application in various fields such as nonlinear optics, quantum optics, device physics and the like due to the superior characteristics of extremely low photon loss rate, ultra-small mode volume, lower working threshold and the like. Different confinement mechanisms of the optical field from the cavity can divide the optical microcavity into three forms: fabry-Perot (F-P) type microcavities, Photonic crystal (Photonic crystal) microcavities, and Whispering-gallery-mode (WGM) microcavities. The microdisk laser is a semiconductor laser with a whispering gallery mode microcavity whose optical field mode is established by total reflection at the edge of the microdisk due to the refractive index difference between the microdisk and air. The micro-disk laser has the advantages of small volume, high quality factor, large free spectrum width, simple structure, easy integration and the like, and has wide application prospect in the aspects of optical communication, optical interconnection, optical information processing and the like.

At present, a microdisk laser is generally manufactured by growing an epitaxial layer material on a substrate, then forming a cylindrical structure with a vertical side surface by non-selective etching, then selectively etching the lower part of the cylinder inwards to obtain a laser structure with a support pillar supporting the microdisk, and finally manufacturing a metal electrode above the microdisk for realizing electric injection into the microdisk laser. In the micro-disk laser, the edge of the micro-disk extends out of the supporting column and is exposed to the air, and the light is limited at the edge of the micro-disk due to the large refractive index difference between the micro-disk and the air, so that a disk-shaped micro-cavity is formed. However, if the metal electrode contacts the edge of the microdisc, the optical field mode in the microdisc resonator couples into the metal electrode, which causes mode loss, and the yield of the microdisc laser is reduced. In order to ensure the product yield of the microdisk laser, the area of the metal electrode is generally strictly limited, and the metal electrode is prepared above the microdisk by adopting an expensive electron beam lithography process, so that the difficulty of industrial production of the microdisk laser is increased, and the production cost is high.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to overcome the defects of high preparation difficulty and high production cost of the microdisk laser in the prior art.

Therefore, the invention provides the following technical scheme:

in a first aspect, the present invention provides a microdisk laser comprising:

a substrate;

the optical microcavity unit is arranged on the substrate and provided with a disc-shaped microcavity;

the electric connection unit is arranged on one side surface, far away from the substrate, of the optical microcavity unit and is used for injecting current into the optical microcavity unit;

the planarization unit wraps the substrate, the electric connection unit and the optical microcavity unit, a continuous plane is formed on one side, back to the optical microcavity unit, of the electric connection unit, and the electric connection unit is attached to the continuous plane;

and the first electrode is arranged on the continuous plane and is in contact connection with the electric connection unit.

Preferably, in the micro disk laser, a projected area of the first electrode on the substrate is larger than a projected area of the electrical connection unit on the substrate.

Further preferably, in the microdisk laser, a projected area of the electrical connection unit on the substrate is larger than a projected area of the optical microcavity unit on the substrate.

Preferably, in the microdisk laser, the optical microcavity unit includes:

a first support layer;

the first micro-disc layer is arranged between the first support column layer and the electric connection unit, the edge of the first micro-disc layer protrudes out of the first support column layer and extends in the flattening unit, and the refractive index of the first micro-disc layer is larger than that of the flattening unit.

Further preferably, in the microdisk laser as described above, the first microdisk layer includes a quantum heterostructure based on semiconductor material, the quantum heterostructure being selected from at least one of quantum dots, quantum wires, quantum hydrazines, and bulk structures;

preferably, the semiconductor material is a GaAs-based material or an InP-based material.

Preferably, in the micro disk laser, the electrical connection unit includes:

the second strut layer is arranged on one side surface, back to the first strut layer, of the first micro disc layer, and the edge of the first micro disc layer protrudes out of the second strut layer and extends in the flattening unit;

and the second micro disc layer is arranged between the second support column layer and the first electrode, and the edge of the second micro disc layer protrudes out of the second support column layer and extends in the planarization unit.

Further preferably, in the microdisk laser, the first pillar layer and the second pillar layer are formed of the same semiconductor material.

Preferably, the microdisk laser further includes a second electrode disposed on a side of the substrate opposite to the optical microcavity unit.

In a second aspect, the present invention provides a method for preparing a microdisk laser, comprising the following steps:

s1, preparing an optical microcavity unit with a disc-shaped microcavity and an electric connection unit for injecting current into the optical microcavity unit on a substrate in sequence;

s2, coating a planarization material on the outer sides of the substrate, the optical microcavity unit and the electric connection unit, and etching the planarization material to enable the planarization material to form a continuous plane structure attached to one side surface, back to the optical microcavity unit, of the electric connection unit, so as to obtain a planarization unit;

and S3, preparing a first electrode in contact connection with the electric connection unit on the continuous plane to obtain the microdisk laser.

Preferably, in the above preparation method, the step S3 further includes:

and preparing a second electrode on one side of the substrate, which is opposite to the optical microcavity unit.

Preferably, in the above preparation method, the step S1 includes:

s11, epitaxially growing a lower limiting layer, an active layer, an upper limiting layer and an electrode contact layer on the substrate in sequence to form a semiconductor epitaxial wafer on the substrate;

s12, depositing a protective layer on the semiconductor epitaxial wafer;

s13, carrying out patterning treatment on the protective layer to obtain a patterned protective layer; the patterned protective layer corresponds to a first region of the semiconductor epitaxial wafer, and a second region of the semiconductor epitaxial wafer is positioned at the periphery of the first region;

s14, performing an etching process to remove the semiconductor epitaxial wafer in the second region;

s15, executing a selective etching process to remove the patterned protective layer, wherein the lower limiting layer and the upper limiting layer are etched inwards along a direction vertical to the epitaxial growth direction to correspondingly obtain a first pillar layer and a second pillar layer; the edge of the active layer extends out of the first support layer and the second support layer to form a suspended structure, and a first micro disc layer is obtained; and the edge of the electrode contact layer extends out of the second support layer to form a suspended structure, so that a second micro-disc layer is obtained.

Further preferably, in the above preparation method, the step S14 includes:

and executing a wet etching process, immersing the semiconductor epitaxial wafer in wet etching liquid along the epitaxial growth direction, removing the semiconductor epitaxial wafer positioned in the second region, and sequentially reducing the immersion depth from the electrode contact layer to the lower limiting layer in the wet etching liquid.

Further preferably, in the above preparation method, the step S14 further includes:

and performing an etching process to partially etch the substrate in the second region so as to form a protrusion on the substrate, wherein the protrusion is in contact with the lower limiting layer.

Preferably, in the above preparation method, the step S2 includes:

etching the planarization material until the electric connection unit is exposed; and continuously etching the exposed area of the electric connection unit to ensure that the surface of one side of the electric connection unit, which is back to the optical microcavity unit, is attached to the planarization material to form a continuous plane structure.

The technical scheme of the invention has the following advantages:

1. the invention provides a microdisk laser which comprises a substrate, an optical microcavity unit, an electric connection unit, a flattening unit and a first electrode, wherein the optical microcavity unit and the first electrode are separated by the electric connection unit, the first electrode is not directly contacted with the optical microcavity unit with a dished microcavity, and energy loss caused by mode coupling into the electrode due to the fact that the electrode is contacted with the edge of the optical microcavity can be avoided. And arranging a flattening unit, wherein the electric connection unit is attached to the continuous plane, so that the first electrode positioned on the continuous plane can be in contact connection with the electric connection unit. The other side of the electric connection unit is contacted with the optical microcavity unit and can be used as a connection channel of the optical microcavity unit and the first electrode to realize the electric connection of the optical microcavity unit and the first electrode, current is injected into the optical microcavity unit, so that the optical microcavity unit is electrically excited to radiate photons, the light can be totally reflected when being transmitted at the edge of the disc-shaped microcavity, and the light field mode is selectively enhanced to emit laser.

Because the optical microcavity unit is separated from the first electrode in an opposite mode, the size of the first electrode is not limited by the disc-shaped microcavity, and the first electrode with a large area can be prepared under the support of the flattening unit. Because the size of the first electrode is not strictly limited, an expensive electron beam lithography process is not needed when the first electrode is prepared, the preparation difficulty and the manufacturing cost of the micro-disk laser are reduced, and the large-scale industrial production of the micro-disk laser is facilitated.

2. According to the micro-disk laser provided by the invention, the projection area of the electric connection unit on the substrate is larger than the projection area of the electric connection unit on the substrate. The area of the first electrode is increased, so that heat in the micro-disk laser is dissipated through the first electrode with a larger area, and the heat dissipation effect of the micro-disk laser is favorably improved. Meanwhile, the contact resistance of the first electrode and the electric connection unit is reduced, so that the performance and the reliability of the device are improved, and the micro-disc laser with low resistance and low thermal resistance is obtained.

Furthermore, the projection area of the electric connection unit on the substrate is larger than the projection area of the optical microcavity unit on the substrate, the area of the electric connection unit is increased, the contact area of the electric connection unit and the first electrode is increased, meanwhile, the area of the optical microcavity unit is further reduced, the size of the dish-shaped microcavity is reduced, the distance between optical field modes in the dish-shaped microcavity is increased, single mode output is achieved, the current of the first threshold is reduced, and the microdisc laser with the low threshold, the low energy consumption and the high quality factor is obtained.

3. The invention provides a microdisk laser, wherein the optical microcavity unit comprises: a first support layer; the first micro-disc layer is arranged between the first support layer and the electric connection unit, the edge of the first micro-disc layer protrudes out of the first support layer and extends in the flattening unit, and the refractive index of the first micro-disc layer is larger than that of the flattening unit.

The edge of the first micro-disc layer protrudes out of the first support layer and extends in the flattening unit, the first micro-disc layer with high refractive index is coated by the flattening unit with low refractive index, so that light is totally reflected at the edge of the first micro-disc layer, and a disc-shaped micro-cavity with a whispering gallery mode is formed in the first micro-disc layer. On one hand, the first support layer supports the first micro-disc layer on the substrate, and because the edge of the first micro-disc layer protrudes out of the first support layer, strong limitation on an optical field in the first micro-disc layer is formed in the vertical direction, and optical loss in a disc micro-cavity is reduced; on the other hand, the first support column layer can be used as a current channel for introducing current into the first micro-disk layer.

4. The invention provides a microdisk laser, wherein an electric connection unit comprises: the second strut layer is arranged on one side surface of the first micro disc layer back to the first strut layer, and the edge of the first micro disc layer protrudes out of the second strut layer and extends in the flattening unit; and the second micro disc layer is arranged between the second support column layer and the first electrode, and the edge of the second micro disc layer protrudes out of the second support column layer and extends in the planarization unit.

The electric connection unit supports the second micro-disc layer on the first micro-disc layer through the second support column layer, the edge of the first micro-disc layer protrudes out of the second support column layer to ensure that the first micro-disc layer is coated by the flattening unit with the relatively low refractive index, strong limitation on an optical field is formed at the edge of the first micro-disc layer, and formation of a disc-shaped micro-cavity in the first micro-disc layer is ensured. The second support column layer supports the second micro disc layer, the edge of the second micro disc layer protrudes out of the second support column layer and has a relatively large area, and the second micro disc layer is directly contacted with the first electrode, so that current is injected into the first micro disc layer through the second micro disc layer and the second support column layer. The second micro-disk layer is in contact with the first electrode in a relatively large area, which is beneficial to reducing the resistance of the micro-disk laser and improving the heat dissipation.

5. According to the preparation method of the microdisk laser, the substrate, the optical microcavity unit and the electric connection unit are coated with the planarization material, so that the planarization material forms a continuous plane structure attached to the surface of one side, opposite to the optical microcavity unit, of the electric connection unit, and the planarization unit is obtained. The first electrode is prepared on the flattening unit, the size of the first electrode is not required to be strictly limited, the use of an expensive electron beam lithography process is avoided, the preparation difficulty and the manufacturing cost of the micro-disk laser are reduced, the preparation efficiency of the device is improved, and the realization of industrial mass production is facilitated. The first electrode and the optical microcavity unit are separated by the electric connection unit and the flattening unit, so that optical loss caused by coupling of a square mode into the first electrode due to the fact that the first electrode contacts the edge of the optical microcavity unit is avoided.

6. According to the preparation method of the microdisk laser, the lower limiting layer, the active layer, the upper limiting layer and the electrode contact layer which are positioned in the second area are removed by executing a wet etching process. By utilizing the isotropy of the wet etching process, the width of the transverse etching is close to the depth of the vertical etching. Therefore, the larger the immersion depth in the wet etching liquid, the larger the lateral etching width thereof, and the smaller the width of the remaining portion after the wet etching. That is, after wet etching, the widths of the remaining portions of the electrode contact layer, the upper confinement layer, the active layer, and the lower confinement layer are sequentially reduced, and an inverted trapezoid having a long side below an upper short side is present in a vertical cross section. And performing a selective etching process on the device structure after the wet etching, so that a second micro-disc layer, a second support column layer, a first micro-disc layer and a second support column layer, which have the projection areas on the substrate reduced in sequence, can be obtained, and the projection area of the electric connection unit on the substrate is larger than the projection area of the optical microcavity unit on the substrate. Because the photoetching technology with higher precision requirement is not needed in the preparation process, the preparation difficulty and the preparation cost of the micro-disk laser are effectively reduced, and the preparation efficiency of the micro-disk laser is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic structural view of a semiconductor laser provided in a first embodiment of the present invention;

fig. 2 is a schematic structural view of a semiconductor laser provided in a second embodiment of the present invention;

fig. 3 is a schematic view of a fabrication process of a semiconductor laser provided in a first embodiment of the present invention; fig. 4 is a schematic view of a fabrication process of a semiconductor laser provided in a first embodiment of the present invention; fig. 5 is a schematic view of a fabrication process of a semiconductor laser provided in a first embodiment of the present invention; fig. 6 is a schematic view of a fabrication process of a semiconductor laser provided in a first embodiment of the present invention; fig. 7 is a schematic view of a fabrication process of a semiconductor laser provided in a first embodiment of the present invention; fig. 8 is a schematic view of a fabrication process of a semiconductor laser provided in a first embodiment of the present invention; fig. 9 is a schematic view of a fabrication process of a semiconductor laser provided in a first embodiment of the invention; fig. 10 is a schematic view of a fabrication process of a semiconductor laser provided in a first embodiment of the invention;

fig. 11 is a schematic view of a fabrication process of a semiconductor laser provided in a second embodiment of the present invention; fig. 12 is a schematic view of a fabrication process of a semiconductor laser provided in a second embodiment of the invention;

description of reference numerals:

1-a first electrode;

2-an electrical connection unit, 21-a second micro-disc layer, 22-a second support column layer;

3-optical microcavity unit, 31-first microdisk layer, 32-first support layer;

4-a planarization unit;

5-a substrate;

6-a second electrode;

21 '-electrode contact layer, 22' -upper confinement layer, 31 '-active layer, 32' -lower confinement layer, 7 '-protective layer, 8' -photoresist.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Example 1

The present embodiment provides a microdisk laser, as shown in fig. 1, including a substrate 5, an optical microcavity unit 3, an electrical connection unit 2, a planarization unit 4, a first electrode 1, and a second electrode 6. The optical microcavity unit 3 is disposed on the substrate 5 and has a dish-shaped microcavity, and the electrical connection unit 2 is disposed on a side of the optical microcavity unit 3 opposite to the substrate 5. The flattening unit 4 covers the substrate 5, the optical microcavity unit 3, and the electrical connection unit 2, and forms a continuous plane attached to the electrical connection unit 2 on a side of the electrical connection unit 2 opposite to the optical microcavity unit 3. The first electrode 1 is located on the continuous plane of the planarization unit 4 and is in contact connection with the electrical connection unit 2. When the micro-disk laser works, an external electric field applies forward bias voltage to the micro-disk laser through the first electrode 1 and the second electrode 6, forward current is conducted in the micro-disk laser, the number of particles generated in the optical microcavity unit 3 is reversed, and photons are radiated by the recombination of electrons and holes. Light is reflected and transmitted for many times on the total reflection interface of the disc-shaped micro-cavity and oscillates to generate resonance, so that the light field in a specific mode is selectively enhanced, and laser emission is realized. The disc-shaped micro-cavity has a simple structure and a strong limiting effect on light, so that the quality factor of the micro-disc laser can be improved, and the miniaturization and high integration degree of the micro-disc laser are realized.

It should be noted that, when an electrode is prepared on a micro-disk, in order to avoid loss of coupling of an optical field into the first electrode 1 caused by contact between the edge of the micro-disk and the electrode, the size of the electrode needs to be strictly limited, and the electrode needs to be manufactured within the range of the micro-disk. In order to ensure the formation of the micro-cavity, a micro-disc with a small volume is usually required to be manufactured, so that the disc-shaped micro-cavity of the micro-disc is in the wavelength order of light in a semiconductor medium to generate a quantum effect, and the small volume of the micro-disc further increases the difficulty and the cost for manufacturing an electrode on the micro-disc.

In order to solve the above problem, in the microdisk laser provided in this embodiment, the electrical connection unit 2 is disposed between the optical microcavity unit 3 and the first electrode 1, so that the first electrode 1 and the optical microcavity unit 3 are relatively separated, and the optical field in the dished microcavity is prevented from being coupled into the first electrode 1 due to the first electrode 1 contacting the edge of the dished microcavity. The electrical connection unit 2 serves as a connection channel between the first electrode 1 and the optical microcavity unit 3, so that current is injected into the optical microcavity unit 3 through the electrical connection unit 2 to achieve electrical connection between the first electrode 1 and the optical microcavity unit 3. The first electrode 1 is supported by the continuous plane of the flattening unit 4, and the first electrode 1 with a large area is suitable for being supported while realizing ohmic contact between the electric connection unit 2 and the first electrode 1, so that the contact resistance in the micro-disk laser is reduced, heat is radiated through the first electrode 1 with a large area, and the thermal resistance in the micro-disk laser is reduced. On the other hand, because the size of the first electrode 1 is not strictly limited, the preparation difficulty and the manufacturing cost of the electrode are reduced, and the industrial mass production of the microdisk laser is facilitated.

Specifically, the optical microcavity unit 3 includes a first pillar layer 32 on the substrate 5, and a first microdisk layer 31 between the first pillar layer 32 and the electrical connection unit 2. The electrical connection unit 2 includes a second pillar layer 22 disposed on a side of the first micro-disk layer 31 opposite to the first pillar layer 32, and a second micro-disk layer 21 disposed between the second pillar layer 22 and the first electrode 1. The substrate 5, the first pillar layer 32, the first micro-disk layer 31, the second pillar layer 22 and the second micro-disk layer 21 are coated with the planarization unit 4, the planarization unit 4 forms a continuous plane on one side of the second micro-disk layer 21 opposite to the optical microcavity unit 3, and the second micro-disk is attached to the continuous plane. The first electrode 1 is located on the continuous plane and is connected to the first microdisk layer 31 in contact therewith, and the second electrode 6 is located on the side of the substrate 5 facing away from the first pillar layer 32. The edge of the first micro disc layer 31 protrudes from the first pillar layer 32 and the second pillar layer 22 and extends in the planarization unit 4, for example, the first micro disc layer 31 is disc-shaped, the first pillar layer 32 and the second pillar layer 22 are cylinders with a bottom diameter smaller than that of the first micro disc layer 31, and the first micro disc layer 31 is located between the two layers such that the edge protrudes from the first pillar layer 32 and the second pillar layer 22. The materials forming the first microdisk layer 31 and the planarization unit 4 are selected such that the refractive index of the first microdisk layer 31 > the refractive index of the planarization unit 4. The first microdisk layer 31 with a high refractive index is coated by the planarization unit 4 with a low refractive index, and light in the first microdisk layer 31 is totally reflected on a contact interface of the two layers, so that a disc-shaped microcavity based on a whispering gallery mode is formed in the first microdisk layer 31. Since the edge of the first microdisk layer 31 protrudes beyond the first pillar layer 32 and the second pillar layer 22, a strong limitation to the light field in the first microdisk layer 31 is formed in the vertical direction, and scattering loss of light in the first microdisk layer 31 is avoided. The first support column layer 32 and the second support column layer 22 disposed on two sides of the first micro disc layer 31 can serve as a communication channel between the first micro disc layer 31 and the first electrode 1 and the second electrode 6 while supporting the first micro disc layer 31 and the second micro disc layer 21, and current is injected into the first micro disc layer 31 to excite laser in the disc-shaped micro cavity of the first micro disc layer 31. The edge of the second micro-disk layer 21 protrudes from the second pillar layer 22 and extends in the planarization unit 4, for example, the second pillar layer 22 is a cylinder, the second micro-disk layer 21 is a disk with a diameter larger than the diameter of the bottom surface of the second pillar layer 22, the second pillar layer 22 supports the second micro-disk layer 21, so that the edge of the second micro-disk layer 21 protrudes from the second pillar layer 22, and ohmic contact with the second electrode 6 is realized in a larger area, which is beneficial to reducing the resistance of the micro-disk laser and improving the heat dissipation effect in the device.

As a preferred embodiment, as shown in fig. 1, a projected area of the first electrode 1 on the substrate 5 is larger than a projected area of the electrical connection unit 2 on the substrate 5, that is, a projected area of the first electrode 1 on the substrate 5 is larger than a projected area of the second microdisk layer 21 on the substrate 5, the first electrode 1 completely covers the second microdisk layer 21, and by increasing an area of the first electrode 1, heat is dissipated through the first electrode 1 having a larger area, so that the heat dissipation performance of the device is improved; meanwhile, the first electrode 1 and the second microdisk layer 21 have the largest contact area, and the internal resistance of the device is reduced. In addition, the increase of the area of the first electrode 1 reduces the precision requirement of the manufacture of the first electrode, and reduces the difficulty of the manufacture of the device.

As an optional implementation mode, the first electrode 1 is connected with an external power supply anode to serve as a P-type electrode; the second electrode 6 is connected with the negative electrode of the external power supply, is used as an N-type metal electrode and is connected with the negative electrode of the external power supply. The first electrode 1 and the second electrode 6 may have a single-layer structure formed of a metal material having good conductivity, such as Cr, Au, Ni, Ti, or the like, or a stacked-layer structure formed by stacking different metal materials, such as Cr/Au, Ni/Au, Ti/Au, or the like. The second microdisk layer 21, the second pillar layer 22, the first microdisk layer 31, the first pillar layer 32, and the substrate 5 are selected from group iii-v semiconductor materials, such as InP-based materials, GaAs-based materials, and the like. Wherein, the second microdisk layer 21 and the second pillar layer 22 between the first electrode 1 and the first microdisk layer 31 are formed of P-type semiconductor material, and the first pillar layer 32 and the substrate 5 between the second electrode 6 and the first microdisk layer 31 are formed of N-type semiconductor material. The first microdisk layer 31 includes a Quantum heterostructure based on semiconductor materials, which may select at least one of Quantum dots (Quantum dots), Quantum wires (Quantum wires), Quantum wells (Quantum wells), and Bulk structures (Bulk). For example, the substrate 5 is formed of an N-type GaAs material, the first pillar layer 32 is formed of an N-type AlGaAs material, the first microdisk layer 31 has a single-quantum hydrazine structure or a multiple-quantum hydrazine structure in which GaAs and InGaAs are alternately stacked, the second pillar layer 22 is formed of a P-type AlGaAs material, and the second microdisk layer 21 is formed of a P-type GaAs material. The first pillar layer 32 and the second pillar layer 22 are respectively used as an N-type limiting layer and a P-type limiting layer which are positioned at two sides of the first micro-disc layer 31, and limit carriers in a disc-shaped micro-cavity of the first micro-disc layer 31, so that the device gain of the micro-disc laser is improved. The first support layer 32 and the second support layer 22 are made of the same semiconductor material, so that the first support layer 32 and the second support layer 22 can be synchronously obtained through selective corrosion treatment in the preparation process of a semiconductor device, the automatic alignment of the first micro-disc layer 31 and the second micro-disc layer 21 is realized, and the process difficulty of micro-disc laser preparation is reduced. The planarization unit 4 is formed by coating a planarization material, specifically benzocyclobutene, on the outer portions of the substrate 5, the first microdisc layer 31, the first support layer 32, the second microdisc layer 21 and the second support layer 22, wherein the planarization material is firstly capable of forming a total reflection section at the edge of the first microdisc layer 31 in contact with the planarization unit 4 due to the fact that the refractive index of the semiconductor material is smaller than that of the first microdisc layer 31, and a disk-shaped microcavity in the first microdisc layer 31 is guaranteed; in addition, benzocyclobutene is used as an electrical insulating material with higher planarization rate and film-forming property, thereby being beneficial to improving the device strength and the sealing property of the micro-disk laser and optimizing the device performance.

As an alternative embodiment, the first electrode 1 can be connected to a negative power supply electrode as an N-type electrode, and the second electrode 6 can be connected to a positive power supply electrode as a P-type electrode. At this time, the second microdisk layer 21 and the second pillar layer 22 between the first electrode 1 and the first microdisk layer 31 are selectively formed of an N-type semiconductor material, and the substrate 5 and the first pillar layer 32 between the second electrode 6 and the first microdisk layer 31 are selectively formed of a P-type semiconductor material. As a further alternative, the substrate 5 may alternatively be formed of an insulating material, for example, an undoped GaAs substrate. At this time, if the first electrode 1 is a P-type electrode and the second electrode 6 is an N-type electrode, an N-type electrode contact layer is epitaxially grown on one side of the substrate 5 facing the first pillar layer 32. The second electrode 6 may be disposed on a continuous plane of the planarization unit 4 on the same side as the first electrode 1, a through hole suitable for extending the second electrode 6 is opened on the planarization unit 4, and the second electrode 6 is in ohmic contact with the N-type electrode contact layer on the substrate 5 through the through hole. As a modification, if the first electrode 1 is an N-type electrode and the second electrode 6 is a P-type electrode, a P-type electrode contact layer is epitaxially grown on a side of the substrate 5 facing the first pillar layer 32, and the second electrode 6 is in ohmic contact with the P-type electrode contact layer on the substrate 5 through the via hole.

As another alternative, the first microdisk layer 31 and the second microdisk layer 21 may have other shapes, such as a polygon, an ellipse, and the like, so long as it is ensured that a dished microcavity can be formed in the second microdisk layer 21. As a further alternative, the first pillar layer 32 and the second pillar layer 22 may be selected from other shapes, such as a triangular pillar, a quadrangular pillar, and the like, as long as it is ensured that the edge of the first micro disc layer 31 protrudes from the first pillar layer 32 and the second pillar layer 22 and extends within the flattening unit 4, and the edge of the second micro disc layer 21 protrudes from the second pillar layer 22 and extends within the flattening unit 4.

Example 2

This embodiment provides a microdisk laser, as shown in fig. 2, which is different from the microdisk laser in embodiment 1 in that:

the projected area of the electrical connection unit 2 on the substrate 5 is larger than the projected area of the optical microcavity unit 3 on the substrate 5, that is, the projected area of the second microdisk layer 21 on the substrate 5 is larger than the projected area of the first microdisk layer 31 on the substrate 5, and the diameter of the second microdisk layer 21 is smaller than the diameter of the first microdisk layer 31. When the projection area of setting up first electrode 1 is greater than the projection area of the little dish layer 21 of second in order to increase area of contact between first electrode 1 and the little dish layer 21 of second, further reduce the area of first little dish layer 31 to reduce the volume of first little dish layer 31, improve the interval of the interior light field mode of dish-shaped microcavity, realize the single mode of laser and jet out. In the microdisk laser shown in fig. 2, the first electrode 1, the second microdisk layer 21, and the first microdisk layer 31 are disks with successively decreasing diameters, the first pillar layer 32 and the second pillar layer 22 are circular truncated cones with fan-shaped outer peripheries, and the first pillar layer 32 and the second pillar layer 22 are respectively in contact with the first microdisk layer 31 and the second microdisk layer 21 with the largest-diameter transverse cross section, so that a good support for the first microdisk layer 31 and the second microdisk layer 21 is formed while a disk-shaped microcavity is formed in the first microdisk layer 31.

Example 3

This example provides a method for manufacturing the microdisk laser in example 1, as shown in fig. 3 to 10, which specifically includes the following steps:

s1, preparing an optical microcavity unit 3 having a disc-shaped microcavity and an electrical connection unit 2 for injecting current into the optical microcavity unit 3 in sequence on a substrate 5.

S11, as shown in fig. 3, a lower limiting layer 32 ', an active layer 31 ', an upper limiting layer 22 ', and an electrode contact layer 21 ' are epitaxially grown in this order on a substrate 5 to form a semiconductor epitaxial wafer on the substrate 5, specifically, an N-type GaAs material is selected to form the substrate 5, an N-type AlGaAs material is epitaxially grown in this order on the substrate 5 as the lower limiting layer 32 ', a single quantum well structure or a multiple quantum well structure formed by alternately stacking InGaAs material and GaAs material is epitaxially grown on the lower limiting layer 32 ' as the active layer 31 ', a P-type AlGaAs material is epitaxially grown on the active layer 31 ' as the upper limiting layer 22 ', and a P-type GaAs material is epitaxially grown on the upper limiting layer 22 ' as the electrode contact layer 21 '. The epitaxial growth method can be selected from PECVD, MOCVD, MBE and LPCVD.

S12, as shown in fig. 4, a dielectric material is deposited on the electrode contact layer 21 'to form a protective layer 7'. The dielectric material can be SiO₂And the deposition method is plasma enhanced chemical vapor deposition and the like.

S13, as shown in fig. 5 and 6, the protective layer 7' is patterned, specifically: and coating a photoresist 8 ' on the protective layer 7 ', performing exposure treatment by using a mask plate to enable the photoresist 8 ' to form a photoresist 8 ' removal region and a photoresist 8 ' retention region, removing the photoresist 8 ' removal region after development, stripping the photoresist 8 ' covered on the protective layer 7 ' after etching the protective layer 7 ' corresponding to the photoresist 8 ' removal region, and obtaining the patterned protective layer 7 '. The region corresponding to the patterned protective layer 7' along the epitaxial growth direction is named as a first region, and the periphery of the first region is defined as a second region.

S14, as shown in fig. 7, a dry etching process is performed to remove the lower stopper layer 32 ', the active layer 31', the upper stopper layer 22 'and the electrode contact layer 21' in the second region, partially remove the substrate 5 in the second region, and form a protrusion on the substrate 5 toward the lower stopper layer 32 'and contacting the lower stopper layer 32'. Specifically, by performing a dry etching process, the lower stopper 32 ', the active layer 31', the upper stopper 22 ', and the electrode contact layer 21' have the same lateral etching depth, and a cylindrical semiconductor epitaxial wafer with a sidewall surface perpendicular to the substrate 5 is obtained. By forming the bump in contact with the lower limiting layer 32' on the substrate 5, it can be ensured that the semiconductor epitaxial wafer to be located in the first region is sufficiently etched.

S15, as shown in fig. 8, a selective etching process is performed to etch the protective layer 7 ', the lower limiting layer 32', and the upper limiting layer 22 'inward in a direction perpendicular to the epitaxial growth direction to completely remove the protective layer 7', and partially remove the lower limiting layer 32 'and the upper limiting layer 22', resulting in the first pillar layer 32 and the second pillar layer 22 having a cylindrical shape. The edge of the non-etched active layer 31' protrudes from the first branchThe column layer 32 and the second column layer 22 form a suspension structure to obtain a disc-shaped first micro disc layer 31; the unetched edge of the electrode contact layer 21' protrudes from the second pillar layer 22 to form a suspension structure, so as to obtain a disk-shaped second microdisk layer 21. For example, the device obtained in step S14 is immersed in a hydrofluoric acid solution to make SiO₂The material, AlGaAs material, is selectively etched, wherein, SiO₂The material has a relatively high dissolution rate in hydrofluoric acid solution and the AlGaAs material has a relatively low dissolution rate and is treated with SiO₂The protective layer 7 ' formed of a material is completely etched, the lower confinement layer 32 ' and the upper confinement layer 22 ' formed of an AlGaAs material are partially etched to form a cylindrical structure having the same diameter, and the active layer 31 ' and the electrode contact layer 21 ' form a disk-shaped structure having the same diameter. The optical microcavity unit 3 is formed by the first pillar layer 32 and the first microdisk layer 31, and the electrical connection unit 2 is formed by the second pillar layer 22 and the second microdisk layer 21.

S2, coating the substrate 5, the optical microcavity unit 3, and the electrical connection unit 2 with a planarization material, and etching the planarization material to form a continuous planar structure attached to the surface of the electrical connection unit 2 opposite to the optical microcavity unit 3, thereby obtaining the planarization unit 4.

Specifically, as shown in fig. 9 and 10, benzocyclobutene material is coated on the outer sides of the substrate 5, the first pillar layer 32, the first micro disc layer 31, the second micro disc layer 21, and the second pillar layer 22, the benzocyclobutene material continues to extend for a certain height after covering the top surface of the second micro disc layer 21, the top surface formed by the benzocyclobutene material is etched until the second micro disc layer 21 is exposed, the exposed area of the second micro disc layer 21 is continuously etched until the top surface of the benzocyclobutene material is attached to the surface of the second micro disc layer 21 opposite to the second pillar layer 22, a continuous planar structure is formed, and the planarization unit 4 is obtained.

S3, preparing the first electrode 1 contacting with the second microdisk layer 21 on the continuous plane of the planarization unit 4, preparing the second electrode 6 on the side of the substrate 5 opposite to the optical microcavity unit 3, and preparing the first electrode 1 and the second electrode 6 by selecting evaporation, sputtering, etc., and annealing to obtain the microdisk laser in fig. 1. Preferably, the area of the first electrode 1 projected on the substrate 5 is larger than the area of the electrically connecting unit 2 projected on the substrate 5, that is, the area of the second microdisk layer 21 projected on the substrate 5, so that the contact area between the second microdisk layer 21 and the first electrode 1 is increased, the resistance value in the microdisk laser is reduced, and the heat dissipation performance is improved.

According to the preparation method, the first support layer 32, the first micro-disc layer 31, the second support layer 22 and the second micro-disc layer 21 can be synchronously formed through a selective etching process, so that the first micro-disc layer 31 and the second micro-disc layer 21 are automatically aligned, the preparation difficulty of the micro-disc laser is reduced, and the preparation efficiency is improved. A second microdisk layer 21 and a second strut layer 22 are arranged between the first microdisk layer 31 and the first electrode 1 at intervals, so that optical loss caused by the fact that the first electrode 1 contacts the edge of the dished microcavity and the optical field mode is coupled into the first electrode 1 is avoided. Meanwhile, by preparing the first electrode 1 on the continuous plane of the planarization unit 4, the size of the first electrode 1 is not strictly limited, and the use of an expensive electron beam lithography process is avoided, so that the preparation difficulty and the manufacturing cost of the first electrode 1 are reduced, and the preparation efficiency is improved.

Example 4

This example provides a method for preparing the microdisk laser in example 2, which is different from the method provided in example 3 in that:

s14, as shown in fig. 11, an etching process is performed to remove the lower stopper layer 32 ', the active layer 31', the upper stopper layer 22 'and the electrode contact layer 21' in the second region, partially remove the substrate 5 in the second region, and form a protrusion on the substrate 5 toward the lower stopper layer 32 'and contacting the lower stopper layer 32'. Specifically, a wet etching process is performed, and the semiconductor epitaxial wafer on the substrate 5 is vertically immersed in the etching solution, so that the immersion depths of the lower limiting layer 32 ', the active layer 31', the upper limiting layer 22 'and the electrode contact layer 21' in the etching solution are sequentially decreased. Because the wet etching has isotropy, the width of the horizontal etching is close to the depth of the vertical etching, that is, the larger the immersion depth is, the larger the horizontal etching width is, the fewer the parts are remained after the etching is finished, the semiconductor epitaxial wafer with the width sequentially increased from the lower limiting layer 32 'to the electrode contact layer 21' is obtained, and the vertical section of the semiconductor epitaxial wafer is in an inverted trapezoid shape with the long side below the upper short side.

S15, as shown in fig. 12, a selective etching process is performed to etch the protective layer 7 ', the lower limiting layer 32', and the upper limiting layer 22 'inward in a direction perpendicular to the epitaxial growth direction, so as to completely remove the protective layer 7', and partially remove the lower limiting layer 32 'and the upper limiting layer 22', thereby obtaining the first pillar layer 32 and the second pillar layer 22 having a circular truncated cone shape with a fan-shaped outer periphery. The edge of the active layer 31' which is not corroded protrudes out of the first pillar layer 32 and the second pillar layer 22 to form a suspension structure, so that a disc-shaped first micro disc layer 31 is obtained; the unetched edge of the electrode contact layer 21' protrudes from the second pillar layer 22 to form a suspension structure, so as to obtain a disk-shaped second microdisk layer 21. Since the width of the resulting upper confinement layer 22 ' is greater than the width of the lower confinement layer 32 ' after the wet etching is performed, the width of the power contact layer is greater than the width of the active layer 31 '. After selective etching, the maximum radius of the transverse section of the first strut layer 32 is less than that of the transverse section of the second strut layer 22, and the radius of the first micro-disc layer 31 is less than that of the second micro-disc layer 21. The first pillar layer 32 and the first microdisk layer 31 form the optical microcavity unit 3, and the second pillar layer 22 and the second microdisk layer 21 form the electrical connection unit 2, wherein the projection area of the electrical connection unit 2 on the substrate 5 is larger than the projection area of the optical microcavity unit 3 on the substrate 5.

According to the preparation method, the electrode contact layer 21 ', the upper limiting layer 22', the active layer 31 'and the lower limiting layer 32' with the widths decreasing in sequence can be obtained by executing a wet etching process; the first micro-disc layer 31 and the second micro-disc layer 21 which are automatically aligned are obtained by combining a wet etching process with a selective etching process, the radius of the second micro-disc layer 21 is larger than that of the first micro-disc layer 31, the contact area between the second micro-disc layer 21 and the first electrode 1 is increased, the heat dissipation performance of the device is improved, the resistance of the device is reduced, the volume of the disc-shaped micro-cavity of the first micro-disc layer 31 is further reduced, the single-mode output of the device is realized, and the micro-disc laser with high performance is obtained. Meanwhile, according to the preparation method, when the first micro-disc layer 31 and the second micro-disc layer 21 with different radiuses are prepared, a photoetching technology with high precision requirements is not needed, the preparation difficulty and the manufacturing cost of the micro-disc laser are effectively reduced, and the preparation efficiency of the micro-disc laser is improved.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims (14)

1. A microdisk laser, comprising:

a substrate;

the optical microcavity unit is arranged on the substrate and provided with a disc-shaped microcavity;

the electric connection unit is arranged on one side surface, far away from the substrate, of the optical microcavity unit and is used for injecting current into the optical microcavity unit;

the planarization unit wraps the substrate, the electric connection unit and the optical microcavity unit, a continuous plane is formed on one side, back to the optical microcavity unit, of the electric connection unit, and the electric connection unit is attached to the continuous plane;

and the first electrode is arranged on the continuous plane and is in contact connection with the electric connection unit.

2. The microdisk laser according to claim 1, characterized in that a projected area of the first electrode on the substrate > a projected area of the electrical connection unit on the substrate.

3. A microdisk laser according to claim 2, characterized in that the projected area of the electrical connection unit on the substrate > the projected area of the optical microcavity unit on the substrate.

4. A microdisk laser according to any one of claims 1-3, characterized in that the optical microcavity unit comprises:

a first support layer;

the first micro-disc layer is arranged between the first support column layer and the electric connection unit, the edge of the first micro-disc layer protrudes out of the first support column layer and extends in the flattening unit, and the refractive index of the first micro-disc layer is larger than that of the flattening unit.

5. The microdisk laser according to claim 4, wherein the first microdisk layer comprises a quantum heterostructure based on semiconductor materials, the quantum heterostructure being selected from at least one of quantum dots, quantum wires, quantum hydrazines, and bulk structures;

preferably, the semiconductor material is a GaAs-based material or an InP-based material.

6. The microdisk laser according to claim 4 or 5, wherein the electrical connection unit comprises:

the second strut layer is arranged on one side surface, back to the first strut layer, of the first micro disc layer, and the edge of the first micro disc layer protrudes out of the second strut layer and extends in the flattening unit;

and the second micro disc layer is arranged between the second support column layer and the first electrode, and the edge of the second micro disc layer protrudes out of the second support column layer and extends in the planarization unit.

7. The microdisk laser of claim 6, wherein the first pillar layer and the second pillar layer are formed of a same semiconductor material.

8. The microdisk laser according to any one of claims 1-7, further comprising a second electrode disposed on a side of the substrate opposite the optical microcavity element.

9. A preparation method of a microdisk laser is characterized by comprising the following steps:

s1, preparing an optical microcavity unit with a disc-shaped microcavity and an electric connection unit for injecting current into the optical microcavity unit on a substrate in sequence;

s2, coating a planarization material on the outer sides of the substrate, the optical microcavity unit and the electric connection unit, and etching the planarization material to enable the planarization material to form a continuous plane structure attached to one side surface, back to the optical microcavity unit, of the electric connection unit, so as to obtain a planarization unit;

and S3, preparing a first electrode in contact connection with the electric connection unit on the continuous plane to obtain the microdisk laser.

10. The method for preparing as claimed in claim 9, wherein the step S3 further comprises:

and preparing a second electrode on one side of the substrate, which is opposite to the optical microcavity unit.

11. The production method according to claim 9 or 10, wherein the step S1 includes:

s11, epitaxially growing a lower limiting layer, an active layer, an upper limiting layer and an electrode contact layer on the substrate in sequence to form a semiconductor epitaxial wafer on the substrate;

s12, epitaxially growing a protective layer on the semiconductor epitaxial wafer;

s13, carrying out patterning treatment on the protective layer to obtain a patterned protective layer; the patterned protective layer corresponds to a first region of the semiconductor epitaxial wafer, and a second region of the semiconductor epitaxial wafer is positioned at the periphery of the first region;

s14, performing an etching process to remove the semiconductor epitaxial wafer in the second region;

s15, executing a selective etching process to remove the patterned protective layer, wherein the lower limiting layer and the upper limiting layer are etched inwards along a direction vertical to the epitaxial growth direction to correspondingly obtain a first pillar layer and a second pillar layer; the edge of the active layer extends out of the first support layer and the second support layer to form a suspended structure, and a first micro disc layer is obtained; and the edge of the electrode contact layer extends out of the second support layer to form a suspended structure, so that a second micro-disc layer is obtained.

12. The method for preparing a composite material according to claim 11, wherein the step S14 includes:

and executing a wet etching process, immersing the semiconductor epitaxial wafer in wet etching liquid along the epitaxial growth direction, removing the semiconductor epitaxial wafer positioned in the second region, and sequentially reducing the immersion depth from the electrode contact layer to the lower limiting layer in the wet etching liquid.

13. The production method according to claim 11 or 12, wherein the step S14 further includes:

and performing an etching process to partially etch the substrate in the second region so as to form a protrusion on the substrate, wherein the protrusion is in contact with the lower limiting layer.

14. The method for preparing a composite material according to claim 9, wherein the step S2 includes:

etching the planarization material until the electric connection unit is exposed; and continuously etching the exposed area of the electric connection unit to ensure that the surface of one side of the electric connection unit, which is back to the optical microcavity unit, is attached to the planarization material to form a continuous plane structure.

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