CN112038886A - VCSEL laser and manufacturing method thereof - Google Patents

Abstract

The invention provides a VCSEL laser and a manufacturing method thereof.A metal nano layer is constructed on the surface of a light-emitting structure, so that the surface of the light-emitting structure forms a plasmon resonance effect and a topological two-dimensional photonic crystal; when electrons and holes are injected into the laser and limited in the active layer to perform composite luminescence, generated evanescent waves are coupled to a laser resonant cavity to form effective feedback; meanwhile, the surface plasmon resonance effect formed by the periodic structure of the metal nano layer is matched with the topological two-dimensional photonic crystal formed by the periodic structure of the metal nano layer, so that the boundary reflection caused by the metal nano layer is only generated near the center of the Brillouin area, the number of laser resonant cavity modes capable of obtaining effective feedback is limited, the modes limited by the effective optical field are concentrated near the center of the Brillouin area, and the modes have very large momentum components in the direction vertical to the metal nano layer, so that the vertical light emitting is realized by the coupling of the modes and the optical field in the laser.

Description

VCSEL laser and manufacturing method thereof

Technical Field

The invention relates to the technical field of VCSELs, in particular to a VCSEL laser and a manufacturing method thereof.

Background

The VCSEL, which is named as Vertical Cavity Surface Emitting Laser (Vertical Cavity Emitting Laser), is developed based on gallium arsenide semiconductor materials, is different from other light sources such as LED (light Emitting Diode) and LD (Laser Diode), has the advantages of small volume, circular output light spot, single longitudinal mode output, small threshold current, low price, easy integration into a large-area array, and the like, and is widely applied to the fields of optical communication, optical interconnection, optical storage, and the like.

At present, the VCSEL has low laser output power and a large divergence angle, and because injected carriers except a part of the injected carriers are compounded to emit photons, the rest of the injected carriers can generate non-radiative compound loss, so that the conversion efficiency of a laser is limited; on the other hand, the cavity has multiple modes simultaneously, wherein the generation of a high-order mode can increase the divergence of the light beam, increase the divergence angle and reduce the brightness of the laser. The above methods of limiting the divergence angle are mostly modifications of the optical cavity portion between the P-type DBR and the N-type DBR. For example, 1, adjusting the size of the oxide aperture can improve the divergence angle, but too large an oxide aperture leads to a decrease in the injection current density, a decrease in the conversion efficiency, and a decrease in the luminance; if the oxide pore diameter is too small, the threshold voltage becomes large. 2. Adjusting the SCH may also improve the divergence angle, however, this may result in poor current spreading, which may lead to poor device thermal performance, increased non-radiative recombination, and reduced conversion efficiency.

In order to increase the single-tube output power of the laser, it is generally necessary to increase the cross-sectional area of the laser beam emitted from the element (i.e., the emission area). When the emergent area is increased to a certain degree, the high-order oscillation mode starts to gain to form multimode lasing, which causes the problems of reduced brightness, unstable mode and the like of the laser.

In view of the above, the present inventors have devised a VCSEL laser and a method for fabricating the VCSEL laser.

Disclosure of Invention

The invention aims to provide a VCSEL laser and a manufacturing method thereof, and aims to solve the problems of small output power and large divergence angle of the VCSEL laser.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a VCSEL laser comprising:

a substrate;

the light-emitting structure is arranged on the surface of the substrate; the light-emitting structure at least comprises an N-type DBR layer, an N-type waveguide limiting layer, a quantum well, a P-type waveguide limiting layer, a P-type oxidation interface stop layer, a metal nano layer and a P-type DBR layer which are sequentially stacked along a first direction; the free vibration frequency of the metal nano layer is matched with the incident light photon frequency of the light-emitting structure, so that the surface of the light-emitting structure forms a plasmon resonance effect, and a topological two-dimensional photonic crystal is constructed and formed; the first direction is perpendicular to the substrate and is directed to the light-emitting structure by the substrate;

and the ohmic contact layer is laminated on one side surface of the P-type DBR layer, which faces away from the metal nano layer.

Optionally, the free vibration frequency of the metal nano layer is greater than or equal to the incident light photon frequency of the light emitting structure, and electrons of the metal nano layer are induced to resonate, so that a plasmon resonance (LSPR) effect is formed on the surface of the light emitting structure.

Preferably, the metal nano-layer comprises a plurality of metal nano-particles formed by dispersed imprinting, or comprises a nano-composite layer composed of a transparent medium layer and a plurality of metal nano-particles dispersed in the transparent medium layer.

Preferably, the size of each metal nanoparticle is uniform, and one or more metal nanoparticles form a periodic unit, the period number is λ/b, where λ is a light source wavelength of the VCSEL chip, and b is an effective refractive index of the metal nanolayer.

Preferably, the metal nanoparticles comprise at least one of Ag, Au, Pt, Pd, Cu, Al.

Preferably, the metal nanoparticles are circular or elliptical or polygonal.

Preferably, the ratio of the sum of the projection areas of all the metal nanoparticles on the substrate to the projection area of the light-emitting structure on the substrate ranges from 20% to 60%.

Preferably, the P-type DBR layer and/or the N-type DBR layer include several sub DBR layers having different refractive indexes; and the thicknesses of the P-type DBR layer and the N-type DBR layer are lambda/4, wherein lambda is the light source wavelength of the VCSEL chip.

The invention also provides a manufacturing method of the VCSEL laser, which comprises the following steps:

step A01, providing a substrate;

a02, growing an N-type DBR layer, an N-type waveguide limiting layer, a quantum well, a P-type waveguide limiting layer and a P-type oxidation interface stop layer on the substrate in sequence to form an epitaxial layer;

step A03, growing a metal nano layer on the surface of the P-type oxidation interface cut-off layer, wherein the free vibration frequency of the metal nano layer is matched with the incident light photon frequency of the light-emitting structure, so that the surface of the light-emitting structure forms a plasmon resonance effect, and a topological two-dimensional photonic crystal is constructed and formed;

step A04, depositing a P-type DBR layer on the surface of the metal nano-layer;

and A05, forming an ohmic contact layer by evaporation, wherein the ohmic contact layer is laminated on the surface of the P-type DBR layer.

Preferably, the step a03 includes forming a plurality of dispersed metal nanoparticles by magnetron sputtering, electrochemical deposition, colloid spin coating, or nanoimprint process after the epitaxial layer is masked, or forming a nano-composite layer composed of a transparent dielectric layer and a plurality of metal nanoparticles dispersed in the transparent dielectric layer.

Preferably, the size of each metal nanoparticle is uniform, and one or more metal nanoparticles form a periodic unit, the period number is λ/b, where λ is a light source wavelength of the VCSEL chip, and b is an effective refractive index of the metal nanolayer.

Preferably, the ratio of the sum of the projection areas of the metal nanoparticles on the substrate to the projection area of the light-emitting structure on the substrate ranges from 20% to 60%.

According to the technical scheme, the VCSEL laser provided by the invention has the advantages that the metal nano layer is constructed on the surface of the light-emitting structure, and the free vibration frequency of the metal nano layer is matched with the incident light photon frequency of the light-emitting structure, so that the plasmon resonance effect is formed on the surface of the light-emitting structure, and a topological two-dimensional photonic crystal is constructed and formed; on one hand, a plasmon resonance effect is formed on the surface of the light-emitting structure, so that the service life of carriers can be prolonged, and the carriers can be compounded in a quantum well as much as possible; on the other hand, when electrons and holes are injected into the laser and limited in the active layer to carry out composite luminescence, generated evanescent waves are coupled to a laser resonant cavity and form effective feedback; meanwhile, the surface plasmon resonance effect formed by the periodic structure of the metal nano layer is matched with the topological two-dimensional photonic crystal formed by the periodic structure of the metal nano layer, so that the boundary reflection caused by the metal nano layer is only generated near the center of the Brillouin area, the number of laser resonant cavity modes capable of obtaining effective feedback is limited, the modes limited by the effective optical field are concentrated near the center of the Brillouin area, and the modes have very large momentum components in the direction vertical to the metal nano layer, so that the vertical light emitting is realized by the coupling of the modes and the optical field in the laser;

further, by: the metal nano particles are distributed periodically, the size of each metal nano particle is uniform, one or more metal nano particles form a periodic unit, the period number is lambda/b, wherein lambda is the light source wavelength of the VCSEL chip, and b is the setting of the effective refractive index of the metal nano layer; and enabling the metal nano layer to form a plasmon resonance effect on the surface of the light-emitting structure, and constructing and forming a topological two-dimensional photonic crystal. Therefore, the metal nano particles form energy band structures of a dipole mode and a quadrupole mode, and limit the light field mode; meanwhile, the effective refractive index of the metal material of the metal nano particles is lower than that of the rest material layers around, so that the optical field in the resonant cavity can be further limited, and the divergence angle is reduced.

Then, through the setting that the ratio value range of the projection area of the metal nano layer on the substrate and the projection area of the light-emitting structure on the substrate is 20% -60%, the light-emitting area of the light-emitting structure can be better met, and simultaneously the local surface of the light-emitting structure can be better played to form the plasmon resonance (LSPR) effect, so that the light-emitting rate of the VCSEL laser is ensured.

Finally, by setting: the P-type DBR layer and/or the N-type DBR layer comprise a plurality of sub-DBR layers with different refractive indexes; and the thicknesses of the P-type DBR layer and the N-type DBR layer are lambda/4, wherein lambda is the light source wavelength of the VCSEL chip. The intensity of electric field of light propagating in the N-type waveguide limiting layer and the P-type waveguide limiting layer can be better limited while the reflectivity of the DBR is not influenced.

According to the technical scheme, the manufacturing method of the VCSEL laser provided by the invention has the beneficial effects that while the beneficial effects of the VCSEL laser are realized, the optimal metal nano-layer is obtained by forming a plurality of metal nano-particles through magnetron sputtering or electrochemical deposition or colloid spin coating or nano-imprinting technology after the surface of the epitaxial layer is masked; meanwhile, the process is simple and convenient to manufacture, and is convenient to produce.

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, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a VCSEL laser according to an embodiment of the present invention;

fig. 2 is a schematic view of an arrangement structure of metal nanoparticles of a VCSEL laser according to an embodiment of the present invention;

fig. 3 is a schematic diagram of another arrangement structure of metal nanoparticles of a VCSEL laser according to an embodiment of the present invention;

fig. 4 is a schematic flow chart of a method for manufacturing a VCSEL laser according to an embodiment of the present invention;

the symbols in the drawings illustrate that: 1. the semiconductor device comprises a substrate, 2, a buffer layer, 3, an N-type DBR layer, 31, a sub N-type DBR layer, 4, an N-type waveguide limiting layer, 5, a quantum well, 6, a P-type waveguide limiting layer, 7, a P-type oxidation interface stop layer, 8, a metal nano layer, 81, metal nano particles, 9, a P-type DBR layer, 91, a sub P-type DBR layer and 10 ohmic contact layers.

Detailed Description

In order to make the content of the present invention clearer, the content of the present invention is further explained below with reference to the attached drawings. The invention is not limited to this specific embodiment. 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.

As shown in fig. 1, a VCSEL laser includes:

a substrate 1;

a light-emitting structure arranged on the surface of the substrate 1; the light-emitting structure at least comprises an N-type DBR layer 3, an N-type waveguide limiting layer 4, a quantum well 5, a P-type waveguide limiting layer 6, a P-type oxidation interface stop layer 7, a metal nano layer 8 and a P-type DBR layer 9 which are sequentially stacked along a first direction; the free vibration frequency of the metal nano layer 8 is matched with the incident light photon frequency of the light-emitting structure, so that the surface of the light-emitting structure forms a plasmon resonance effect, and a topological two-dimensional photonic crystal is constructed; the first direction is perpendicular to the substrate 1 and is directed to the light emitting structure from the substrate 1;

and an ohmic contact layer 10, wherein the ohmic contact layer 10 is laminated on the surface of the P-type DBR layer 9 on the side opposite to the metal nano-layer 8.

Optionally, in an embodiment of the present application, the free vibration frequency of the metal nano-layer 8 is greater than or equal to the incident light photon frequency of the light emitting structure, and electrons of the metal nano-layer 8 are induced to resonate, so that a plasmon resonance (LSPR) effect is formed on the surface of the light emitting structure.

On the basis of the above technical solutions, in other embodiments of the present application, the N-type waveguide confinement layer 4 and the P-type waveguide confinement layer 6 may include several sub-confinement layers, as long as the foregoing ranges and requirements are met, and adaptive changes are performed with reference to the above embodiments, which are not exhaustive herein.

It should be noted that the material types of the substrate 1, the N-type DBR layer 3, the N-type waveguide confinement layer 4, the quantum well 5, the P-type waveguide confinement layer 6, the P-type oxide interface stop layer 7, and the P-type DBR layer 9 may also be unlimited in this embodiment; for example, but not limited to, an aluminum gallium arsenide material system. As long as the free vibration frequency of the nano system is matched with the incident light photon frequency of the light-emitting structure A.

In other embodiments of the present application, a buffer layer 2 is provided between the substrate 1 and the N-type DBR layer 3.

Further, the metal nano-layer 8 includes a plurality of metal nanoparticles 81 formed by dispersed imprinting, or includes a nano-composite layer composed of a transparent medium layer and a plurality of metal nanoparticles dispersed in the transparent medium layer.

Optionally, in an embodiment of the present application, as shown in fig. 2 and fig. 3, each of the metal nanoparticles 81 has a uniform size, and one or more metal nanoparticles form a periodic unit, where the period number is λ/b, where λ is a light source wavelength of the VCSEL chip, and b is an effective refractive index of the metal nanolayer.

Optionally, in an embodiment of the present application, the metal nanoparticles include at least one of Ag, Au, Pt, Pd, Cu, and Al.

Optionally, in an embodiment of the present application, as shown in fig. 2 and 3, the metal nanoparticles are circular, elliptical or polygonal.

Optionally, in an embodiment of the present application, a ratio of a sum of projection areas of all the metal nanoparticles on the substrate 1 to a projection area of the light emitting structure on the substrate 1 ranges from 20% to 60%.

Optionally, in an embodiment of the present application, the P-type DBR layer 9 and/or the N-type DBR layer 3 include several sub-DBR layers having different refractive indexes; and the thickness of the P-type DBR layer 9 and the N-type DBR layer 3 is lambda/4, wherein lambda is the light source wavelength of the VCSEL chip.

It should be noted that, the number of DBR layers of the stator is not limited in the embodiment of the present invention, and may be 1 or several; the present application is not intended to be exhaustive, as long as the aforementioned ranges and requirements are met, and adaptive changes are made with reference to the above-described embodiments.

The embodiment of the present invention further provides a method for manufacturing a VCSEL laser, as shown in fig. 4, the method for manufacturing a VCSEL laser includes the following steps:

step A01, providing a substrate 1;

step A02, growing an N-type DBR layer 3, an N-type waveguide limiting layer 4, a quantum well 5, a P-type waveguide limiting layer 6 and a P-type oxidation interface stop layer 7 on a substrate 1 in sequence to form an epitaxial layer;

step A03, growing a metal nano layer 8 on the surface of a P-type oxidation interface cut-off layer 7, wherein the free vibration frequency of the metal nano layer 8 is matched with the incident light photon frequency of a light-emitting structure, so that the surface of the light-emitting structure forms a plasmon resonance effect, and a topological two-dimensional photonic crystal is constructed and formed;

step A04, depositing a P-type DBR layer 9 on the surface of the metal nano-layer 8;

step a05 is to form an ohmic contact layer 10 by vapor deposition, and the ohmic contact layer 10 is laminated on the surface of the P-type DBR layer 9.

Optionally, in an embodiment of the present application, the step a03 includes forming a plurality of dispersed metal nanoparticles by a magnetron sputtering process, an electrochemical deposition process, a colloid spin coating process, or a nanoimprint process after masking the surface of the epitaxial layer, or forming a nanocomposite layer including a transparent dielectric layer and a plurality of metal nanoparticles dispersed in the transparent dielectric layer. .

Optionally, in an embodiment of the present application, a ratio of a sum of projection areas of the metal nanoparticles on the substrate 1 to a projection area of the light emitting structure on the substrate 1 ranges from 20% to 60%.

According to the technical scheme, the metal nano layer 8 is constructed on the surface of the light-emitting structure, and the free vibration frequency of the metal nano layer 8 is matched with the incident light photon frequency of the light-emitting structure, so that the surface of the light-emitting structure forms a plasmon resonance effect, and the selection of dipole moment corresponding to the photon frequency is realized by controlling the electronic transition rate of the VCSEL laser; on one hand, a plasmon resonance effect is formed on the surface of the light-emitting structure, so that the service life of carriers can be prolonged, and the carriers can be compounded in the quantum well 5 as much as possible; on the other hand, when electrons and holes are injected into the laser and limited in the active layer to carry out composite luminescence, generated evanescent waves are coupled to a laser resonant cavity and form effective feedback; meanwhile, the surface plasmon resonance effect formed by the periodic structure of the metal nano layer is matched with the topological two-dimensional photonic crystal formed by the periodic structure of the metal nano layer, so that the boundary reflection caused by the metal nano layer is only generated near the center of the Brillouin area, the number of laser resonant cavity modes capable of obtaining effective feedback is limited, the modes limited by the effective optical field are concentrated near the center of the Brillouin area, and the modes have very large momentum components in the direction vertical to the metal nano layer, so that the vertical light emitting is realized by the coupling of the modes and the optical field in the laser.

Further, by: the metal nano particles are distributed periodically, the size of each metal nano particle is uniform, one or more metal nano particles form a periodic unit, the period number is lambda/b, wherein lambda is the light source wavelength of the VCSEL chip, and b is the setting of the effective refractive index of the metal nano layer; and enabling the metal nano layer to form a plasmon resonance effect on the surface of the light-emitting structure, and constructing and forming a topological two-dimensional photonic crystal. Therefore, the metal nano particles form energy band structures of a dipole mode and a quadrupole mode, and limit the light field mode; meanwhile, the effective refractive index of the metal material of the metal nano particles is lower than that of the rest material layers around, so that the optical field in the resonant cavity can be further limited, and the divergence angle is reduced.

Then, through the setting that the ratio value range of the projection area of the metal nano layer 8 on the substrate 1 to the projection area of the light-emitting structure on the substrate 1 is 20% -60%, the light-emitting area of the light-emitting structure can be better met, and simultaneously the plasmon resonance (LSPR) effect formed on the local surface of the light-emitting structure can be better exerted, so that the light-emitting rate of the VCSEL laser is ensured.

Finally, by setting: the P-type DBR layer 9 and/or the N-type DBR layer 3 include a plurality of sub-DBR layers having different refractive indices; and the thickness of the P-type DBR layer 9 and the N-type DBR layer 3 is lambda/4, wherein lambda is the light source wavelength of the VCSEL chip. The intensity of the electric field of light propagating in the N-type waveguide confinement layer 4 and the P-type waveguide confinement layer 6 can be better limited without affecting the magnitude of the reflectivity of the DBR.

According to the technical scheme, the manufacturing method of the VCSEL laser provided by the invention has the beneficial effects that while the beneficial effects of the VCSEL laser are realized, after the surface of the epitaxial layer is masked, a plurality of metal nano particles are formed through magnetron sputtering or electrochemical deposition or colloid spin coating or nano imprinting technology, so that the optimal metal nano layer 8 is obtained; meanwhile, the process is simple and convenient to manufacture, and is convenient to produce.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

It is further noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in an article or device that comprises the element.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A VCSEL laser, comprising:

a substrate;

the light-emitting structure is arranged on the surface of the substrate; the light-emitting structure at least comprises an N-type DBR layer, an N-type waveguide limiting layer, a quantum well, a P-type waveguide limiting layer, a P-type oxidation interface stop layer, a metal nano layer and a P-type DBR layer which are sequentially stacked along a first direction; the free vibration frequency of the metal nano layer is matched with the incident light photon frequency of the light-emitting structure, so that the surface of the light-emitting structure forms a plasmon resonance effect, and a topological two-dimensional photonic crystal is constructed and formed; the first direction is perpendicular to the substrate and is directed to the light-emitting structure by the substrate;

and the ohmic contact layer is laminated on one side surface of the P-type DBR layer, which faces away from the metal nano layer.

2. The VCSEL laser of claim 1, wherein the metal nano-layer comprises a plurality of metal nanoparticles formed by dispersion imprinting or a nano-composite layer comprising a transparent dielectric layer and a plurality of metal nanoparticles dispersed in the transparent dielectric layer.

3. The VCSEL laser of claim 1 or 2, wherein each of the metal nanoparticles has a uniform size, and one or more metal nanoparticles constitute a periodic unit, the period number is λ/b, where λ is a light source wavelength of the VCSEL chip, and b is an effective refractive index of the metal nanolayer.

4. A VCSEL laser according to claim 2, wherein said metal nanoparticles comprise at least one of Ag, Au, Pt, Pd, Cu, Al.

5. The VCSEL laser of claim 2, wherein the metal nanoparticles are circular or elliptical or polygonal.

6. The VCSEL laser of claim 2, wherein a ratio of a sum of projected areas of all the metal nanoparticles on the substrate to a projected area of the light emitting structure on the substrate ranges from 20% to 60%.

7. A VCSEL laser according to claim 1, wherein said P-type DBR layer and/or N-type DBR layer comprises several sub-DBR layers having different refractive indices; and the thicknesses of the P-type DBR layer and the N-type DBR layer are lambda/4, wherein lambda is the light source wavelength of the VCSEL chip.

8. A method for manufacturing a VCSEL laser is characterized by comprising the following steps:

step A01, providing a substrate;

a02, growing an N-type DBR layer, an N-type waveguide limiting layer, a quantum well, a P-type waveguide limiting layer and a P-type oxidation interface stop layer on the substrate in sequence to form an epitaxial layer;

step A03, growing a metal nano layer on the surface of the P-type oxidation interface cut-off layer, wherein the free vibration frequency of the metal nano layer is matched with the incident light photon frequency of the light-emitting structure, so that the surface of the light-emitting structure forms a plasmon resonance effect, and a topological two-dimensional photonic crystal is constructed and formed;

step A04, depositing a P-type DBR layer on the surface of the metal nano-layer;

and A05, forming an ohmic contact layer by evaporation, wherein the ohmic contact layer is laminated on the surface of the P-type DBR layer.

9. The method as claimed in claim 8, wherein the step a03 comprises forming a plurality of dispersed metal nanoparticles by magnetron sputtering or electrochemical deposition or colloid spin coating or nanoimprint process after the epitaxial layer is masked, or forming a nano-composite layer consisting of a transparent dielectric layer and a plurality of metal nanoparticles dispersed in the transparent dielectric layer.

10. The method of claim 9, wherein the metal nanoparticles are uniform in size, and one or more metal nanoparticles form a periodic unit, the period number is λ/b, where λ is a wavelength of a light source of the VCSEL chip, and b is an effective refractive index of the metal nanolayer.

Images