CN107887790A - A kind of multi-wavelength GaN base asymmetric quantum well surface-emitting laser and preparation method thereof - Google Patents

Abstract

The invention discloses a kind of multi-wavelength GaN base asymmetric quantum well surface-emitting laser and preparation method thereof, it is related to field of semiconductor lasers.Realize that the multi-wavelength of laser exports as active area using asymmetric quantum well, including two and two or more optical maser wavelength.Device fabrication process includes non-planar metal bonding, laser lift-off, the control of chamber length and graphical distribution Bragg reflector making etc..This multi-wavelength surface launching laser device has huge application potential, available for space precision ranging, terahertz signal generator, photomixing, laser spectroscopy, medical treatment detection and the various fields such as augmented reality (AR) and three-dimensional imaging.The advantage of the present invention also resides in the two-dimensional array structure for being easily achieved device, is especially suitable for large-scale industrialized production, be advantageous to the commercialization of device with it is practical.

Description

A multi-wavelength GaN-based asymmetric quantum well surface-emitting laser and its preparation method

technical field

The invention belongs to the field of semiconductor lasers, in particular to a novel multi-wavelength GaN-based asymmetric quantum well surface-emitting laser and a preparation method thereof.

Background technique

GaN-based materials include GaN, InN, AlN and their ternary or quaternary alloys. They are all direct bandgap semiconductor materials and have high radiative recombination efficiency, and are the third generation semiconductor materials. By adjusting the alloy ratio of GaN-based materials, its forbidden band width can be continuously changed from deep ultraviolet to visible light and then to near infrared. At the same time, GaN materials have stable mechanical and chemical properties, so light-emitting devices based on GaN-based materials have broad application prospects in solid-state lighting, full-color display, high-density optical storage, high-speed laser printing, and communications.

GaN substrate emitting laser is a research hotspot in recent years. Compared with traditional edge-emitting lasers, surface-emitting lasers have many advantages such as single longitudinal mode operation, low threshold, circular symmetrical spot, on-chip testing, and easy realization of two-dimensional array structures. The currently reported GaN-based surface-emitting lasers are mainly dedicated to obtaining single-wavelength laser output of the device (T.C.Lu, C.C.Kao, et al., CW lasing of current injection blue GaN-based vertical cavity surface emitting laser, Appl. Phys. Lett., 92 :141102(2008); C.Holder, J.S.Speck, et al., Demonstration of Nonpolar GaN-based Vertical-Cavity Surface-EmittingLasers, Appl.Phys.Express, 5:092104(2012); G.E.Weng, Y.Mei, et al. al., Low threshold continuous-wave lasing of yellow-green InGaN-QD vertical-cavity surface-emitting lasers, Opt. Epress, 24:15546 (2016)). However, compared with single-wavelength surface-emitting lasers, multi-wavelength surface-emitting lasers have their own characteristics and advantages. It can emit two or more lasers with different wavelengths at the same time, and can modulate these lasers with different wavelengths. These characteristics make multi-wavelength GaN surface-emitting lasers have important application value and great application potential, which can be applied in space precise ranging, terahertz signal generator, optical mixing, laser spectroscopy, medical detection and augmented reality (AR ) and 3D imaging and many other fields.

The current method to achieve multi-mode output of surface emitting lasers is mainly to use a longer cavity length, so that the cavity-mode distance is very short, so that multiple modes can obtain sufficient gain and finally achieve multiple laser wavelength output. But a big limitation of this method is that it lacks controllability to the output laser wavelength, that is, the obtained multiple laser wavelengths are randomly distributed. The structure design of the active region proposed by the invention can effectively solve this problem and realize precise control of the output wavelength of the laser.

Contents of the invention

The purpose of the present invention is to provide a multi-wavelength GaN-based asymmetric quantum well surface-emitting laser and its preparation method, and the present invention also provides a design method for the asymmetric quantum well active region.

The design method of the asymmetric quantum well active region provided by the present invention includes the following two aspects:

(1) A certain number of quantum wells are used.

Wherein, the quantum well is an asymmetric quantum well.

Wherein, the number of quantum wells is preferably two or more.

Wherein, the quantum wells preferably have different well layer thicknesses or different compositions.

Wherein, the well layer thickness and composition of the quantum well are determined by the laser wavelength of the designed surface-emitting laser, so that the luminescence center wavelength of the quantum well with different thickness or composition is consistent with each laser wavelength.

For example, an InGaN/GaN asymmetric quantum well structure is adopted, and one or both of the following two conditions are met: ① InGaN well layer thickness is different; ② InGaN well layer composition is different.

(2) The position of the quantum well in the resonant cavity is precisely designed, so that the quantum well is located at the antinode position of the light field corresponding to the different cavity modes in the resonant cavity, so that the distance between the quantum well and the light field of different cavity modes in the resonant cavity The coupling among them reaches the strongest at the same time, the asymmetric quantum well active area is obtained, and multi-wavelength laser output is realized.

In step (2), the method of placing the asymmetric quantum well at the antinode position of the light field corresponding to the different cavity modes in the resonator is as follows: first, the cavity length of the surface emitting laser is precisely designed, and multiple positions are determined and conform to The required cavity mode, the spatial distribution of the optical field corresponding to each cavity mode in the resonator is independent and determined; then, according to the selected output laser wavelength λ ₁ ... λ _n (corresponding to the cavity mode determined by the above position), Where n≥2, the spatial distribution of these cavity modes corresponding to the light field in the resonator cavity is obtained; finally, the position of the above-mentioned asymmetric quantum well is set, so that the thickness or composition of different well layers with the central wavelength of light emission is λ ₁ ... λ _n The quantum wells are respectively located at the antinode positions of the corresponding light field in the resonant cavity.

In the present invention, the asymmetric quantum well means that the well layer thickness or composition of the quantum wells are different, so that different quantum wells have different emission wavelengths, and this structure can realize effective broadening of the gain spectrum of the active region. At the same time, the cavity length of the laser is precisely designed according to the required laser wavelength, and the above-mentioned asymmetric quantum well is located at the antinode position of the corresponding cavity mode light field in the resonator, so that the asymmetric quantum well and the corresponding cavity mode light in the resonator The coupling between the fields reaches the strongest, and finally realizes simultaneous output of multiple wavelength lasers.

The present invention also provides a method for preparing a multi-wavelength GaN-based asymmetric quantum well surface-emitting laser, which specifically includes the following steps:

(1) On a clean sapphire substrate, grow a GaN-based epitaxial film (epitaxial wafer) with the above-mentioned asymmetric quantum well active region;

In step (1), the preparation of the GaN-based epitaxial thin film can adopt metal organic chemical vapor phase epitaxy (MOCVD), molecular beam epitaxy (MBE), hydride vapor phase epitaxy or magnetron sputtering; Vapor phase epitaxy (MOCVD).

In step (1), the GaN-based epitaxial thin film includes a GaN low-temperature buffer layer, an undoped GaN layer, a Si-doped n-type GaN layer, an InGaN/GaN asymmetric quantum well active region, and a Mg-doped AlGaN layer , Mg-doped p-type GaN layer. In a specific embodiment, in step (1), the GaN-based epitaxial thin film includes a GaN low-temperature buffer layer (30 nanometers), an undoped GaN layer (2 micrometers), a Si-doped n-type GaN layer (2 Micron), InGaN/GaN asymmetric quantum well active region (GaN barrier is 10 nanometers, InGaN wells are 2 nanometers and 5 nanometers respectively, a total of two groups), Mg-doped AlGaN layer (200nm), Mg-doped p-type GaN layer (500nm).

In step (1), high-temperature annealing is preferably performed after the epitaxial wafer growth is completed, so as to increase the hole concentration. The temperature of the high temperature annealing is 400-600 degrees Celsius, preferably 500 degrees Celsius, and it is carried out under vacuum or nitrogen atmosphere.

(2) Fabricate a patterned distributed Bragg reflector on the above-mentioned GaN-based epitaxial film, and then evaporate or sputter the first metal-containing layer on its surface;

In step (2), the method for fabricating the patterned distributed Bragg reflector can adopt photolithography, lift-off, corrosion and etching methods.

In step (2), the distributed Bragg reflector is formed by interlacing and superimposing two kinds of dielectric films with different refractive indices.

Wherein, the thickness (optical thickness) of each layer of the dielectric film is 1/4 of the central wavelength; the central wavelength refers to the average wavelength of all emitted laser light. For example, the laser emission wavelengths are λ ₁ ...λ _n , where (n≥2), then the average wavelength is (λ ₁ +...+λ _n )/n, then the growth thickness of each layer of dielectric film should be equal to (1/ 4) ·(λ ₁ + . . . +λ _n )/n.

Wherein, the dielectric film combination may be TiO ₂ /SiO ₂ , ZrO ₂ /SiO ₂ or Ta ₂ O ₅ /SiO ₂ .

In step (2), the composition of the first metal-containing layer may be one or more of Sn, Au, In, Cu, Pt, Cr, Ni, Ag, Ti.

(3) evaporating or sputtering a second metal-containing layer on the substrate surface;

In step (3), the substrate has good electrical conductivity, and silicon wafers, silicon carbide or copper wafers can be used.

In step (3), the composition of the second metal-containing layer can be selected from one or more of Sn, Au, In, Cu, Pt, Cr, Ni, Ag, Ti.

(4) The above-mentioned first metal-containing layer and the second metal-containing layer are closely bonded, and non-planar metal bonding is carried out in a vacuum or nitrogen atmosphere, and then the sapphire substrate is removed by laser lift-off technology to obtain the sapphire substrate after removal GaN-based epitaxial thin films.

In step (4), after obtaining the GaN-based epitaxial film after removing the sapphire substrate, the GaN-based epitaxial film is transferred to the substrate, and then the thickness of the epitaxial film is reduced to make the polished n-type GaN surface roughness reach 10 below nanometers. In a specific embodiment, the thickness of the epitaxial film is reduced to 2 microns by chemical mechanical polishing (that is, the laser cavity length is controlled to be 2 microns), and the surface roughness of the polished n-type GaN reaches below 10 nanometers, as shown in Figure 6 Show.

(5) Fabricate patterned metal electrodes and patterned distributed Bragg mirrors sequentially on the GaN-based epitaxial film after removing the sapphire substrate to complete the fabrication of the entire resonant cavity.

In step (5), the fabrication of patterned metal electrodes and patterned distributed Bragg reflectors may adopt photolithography, stripping, corrosion and etching methods.

In step (5), the patterned metal electrode can be Ni/Au, Cr/Au, Ti/Au or Pt/Au, etc.; preferably, it is Cr/Au.

In step (5), the reflectivity of the patterned distributed Bragg reflector is slightly lower than that of the patterned distributed Bragg reflector in step (2), which can be realized by reducing the number of dielectric film layers.

(6) separating the GaN-based epitaxial film to obtain the multi-wavelength GaN-based asymmetric quantum well surface-emitting laser.

In step (6), the method for separating the GaN-based epitaxial film includes etching and inductively coupled plasma etching; preferably inductively coupled plasma etching.

The present invention also proposes an asymmetric quantum well active region prepared by the above method.

The present invention also proposes a multi-wavelength GaN-based asymmetric quantum well surface-emitting laser prepared by the above method; the multi-wavelength GaN-based asymmetric quantum well surface-emitting laser has a specially designed asymmetric quantum well active region , can simultaneously obtain two or more stable laser outputs with different wavelengths.

The multi-wavelength GaN-based asymmetric quantum well surface-emitting laser described in the present invention can be applied to space precise ranging, terahertz signal generator, optical mixing, laser spectroscopy, medical detection, augmented reality (AR) and three-dimensional imaging, etc. field.

The beneficial effect of the present invention is that: the present invention provides a novel multi-wavelength GaN-based asymmetric quantum well surface-emitting laser and its preparation method, through the precise design of the active region of the asymmetric quantum well, so that different well layer thickness or different The coupling between the quantum well of the component and the light field of the corresponding cavity mode in the resonator is maximized. Due to the effect of quantum confinement, the thinner the well layer, the stronger the quantum confinement effect, and the higher the quantized energy level in the well, resulting in different wavelengths of light emitted by quantum wells with different well layer thicknesses; and the different components directly lead to the forbidden quantum wells. Different band widths have different luminescent wavelengths. The two asymmetric quantum well structures can realize the perfect matching of the emission wavelengths of different quantum wells and different cavity modes in the resonant cavity by adopting reasonable structural parameters. Using this specially designed asymmetric quantum well as the active region can realize the multi-wavelength laser output of the GaN base surface-emitting laser, including two or more wavelengths.

The invention discloses a multi-wavelength GaN-based asymmetric quantum well surface emitting laser and a preparation method thereof, and relates to the field of semiconductor lasers. The asymmetric quantum well is used as the active region to realize the multi-wavelength output of the laser, including two or more laser wavelengths. The device fabrication process includes non-planar metal bonding, laser lift-off, cavity length control, and fabrication of patterned distributed Bragg reflectors. The multi-wavelength GaN-based asymmetric quantum well surface-emitting laser provided by the present invention has an output wavelength that can be adjusted and changed through the design of the cavity length, and its wavelength covers the entire range of visible light. It is a new type of semiconductor laser with very broad application prospects. It can be applied to many fields such as space precise ranging, terahertz signal generator, optical mixing, laser spectroscopy, medical detection, augmented reality (AR) and three-dimensional imaging.

The preparation method provided by the invention can easily realize the two-dimensional array structure of the multi-wavelength laser, is suitable for large-scale industrial production, has low production cost, and is beneficial to the commercialization and practical application of devices. At the same time, this laser has many advantages that are unique to surface-emitting lasers such as low threshold, circular spot output, and the ability to perform on-chip testing.

Description of drawings

Figure 1 shows the cavity mode distribution in the laser resonator cavity under the condition of setting the cavity length; wherein the cavity mode λ ₁ and the cavity mode λ ₂ are the cavity modes corresponding to the required laser output.

Figure 2 shows the optical field corresponding to the selected cavity mode and the spatial distribution of the asymmetric quantum well in the resonator; where the selected cavity mode is the cavity mode λ ₁ and the cavity mode λ ₂ shown in Figure 1, and the long dashed line is The spatial distribution of the cavity mode λ ₁ light field in the resonant cavity, the short dotted line is the spatial distribution of the cavity mode λ ₂ light field in the resonant cavity; wherein, quantum well 1 emits light at a central wavelength of λ ₂ , which is in the cavity mode λ ₂ light field The antinode position of the field; the quantum well 2 luminescence center wavelength is λ ₁ , which is at the antinode position of the cavity mode λ ₁ light field.

Fig. 3 is a schematic diagram of the structure of the GaN-based epitaxial wafer with the asymmetric quantum well active region used.

Fig. 4 is a schematic diagram of fabricating a patterned distributed Bragg reflector on the surface of p-type GaN.

Figure 5 is a schematic diagram of non-planar metal bonding.

FIG. 6 is a schematic diagram of removing the sapphire substrate by laser lift-off and thinning and polishing n-type GaN.

FIG. 7 is a schematic diagram after fabricating a patterned metal electrode and a patterned distributed Bragg reflector on the surface of the n-type GaN.

FIG. 8 is a schematic diagram of a device after separation by inductively coupled plasma etching (ICP).

Detailed ways

The present invention will be further described in detail in conjunction with the following specific embodiments and accompanying drawings. The process, conditions, experimental methods, etc. for implementing the present invention, except for the content specifically mentioned below, are common knowledge and common knowledge in this field, and the present invention has no special limitation content.

Embodiment 1: Design method of asymmetric quantum well active region.

(1) For example, to prepare a dual-wavelength GaN-based asymmetric quantum well surface-emitting laser with laser wavelengths of λ ₁ and λ ₂ , we can obtain the above two cavity modes (λ ₁ , λ ₂ ) device structure, as shown in Figure 1. Among them, the cavity mode λ ₁ and the cavity mode λ ₂ correspond to two wavelengths of 519 nm and 543 nm respectively, which are obtained under the condition that the laser cavity length is set to 2 microns, and we can achieve the cavity by changing the size of the cavity length Die position adjustment. Software such as TFCalc can be used for the simulation design of the cavity length and cavity mode of the laser.

(2) After setting the cavity length and cavity modes (λ ₁ , λ ₂ ), the next step is to set the spatial position of the asymmetric quantum well in the resonant cavity. As shown in Figure 2, first use TFCalc software to determine the spatial distribution of the optical field corresponding to cavity mode λ ₁ and cavity mode λ ₂ in the resonator, and then place asymmetric quantum wells with different well layer thicknesses or different compositions in the corresponding The antinode position of the light field. In Fig. 2, quantum well 1 is at the antinode of cavity mode λ ₂ light field, and quantum well 2 is at the antinode of cavity mode λ ₁ light field, wherein the luminescence center wavelengths of quantum well 1 and quantum well 2 are designed as λ ₂ and λ respectively ₁ , which is consistent with the corresponding cavity mode.

Through the above two steps, the design of the laser cavity length and the active region of the asymmetric quantum well is completed.

Embodiment 2: Device preparation process flow.

(1) As shown in Figure 3, the GaN-based epitaxial wafer 32 with the asymmetric quantum well active region is grown on the sapphire substrate 31 by MOCVD method, including GaN low-temperature buffer layer (30 nanometers), undoped GaN layer (2 microns), Si-doped n-type GaN layer (2 microns), InGaN/GaN asymmetric quantum well active region (GaN barrier is 10 nanometers, InGaN wells are 2 nanometers and 5 nanometers respectively, a total of two groups) , Mg-doped AlGaN layer (200nm) and Mg-doped p-type GaN layer (500nm), etc., and perform high-temperature annealing after the epitaxial wafer growth is completed to increase the hole concentration.

(2) As shown in Figure 4, the GaN-based epitaxial wafer is subjected to photolithography, and then a distributed Bragg reflector is grown by magnetron sputtering or electron beam evaporation, and then a patterned distributed Bragg reflector 41 is obtained by stripping; The Bragg reflector is stacked by 23 layers of TiO ₂ /SiO ₂ , and the thickness of each layer of dielectric film is 1/4 of the average central wavelength, that is, the growth thickness should be (1/4)·(λ ₁ +λ ₂ )/2, where The reflectivity is above 99%.

A first metal-containing layer (Sn) 51 of 5 micrometers was evaporated on one side of the above-mentioned distributed Bragg mirror.

(3) Evaporate the second metal-containing layer (Sn) 52 on the clean copper sheet 53 at 5 micrometers.

(4) Bond the first and second gold-containing layers together under a vacuum environment, 350°C, and 4MPa pressure, as shown in Figure 5; wherein, the rate of heating up to 350°C is 10°C/min, and at 350°C ℃ for 2 minutes, and then cool down naturally. Use laser lift-off technology to remove the sapphire substrate, transfer the GaN-based epitaxial film to a copper substrate, and then use chemical mechanical polishing to reduce the thickness of the epitaxial film to 2 microns (that is, control the laser cavity length to 2 microns), and polish The final n-type GaN surface roughness reaches below 10 nm, as shown in Figure 6.

(5) Adopt the same method as in step (2) to make the patterned metal electrode 61 and the patterned distributed Bragg reflector 62, and complete the making of the whole resonant cavity, as shown in Figure 7; wherein, the patterned distributed Bragg reflector 62 The size of the DBR is the same as that of the patterned distributed Bragg reflector 41 or slightly smaller (not exceeding 10 microns), and the centers of the two should be aligned. Moreover, the reflectivity of the patterned distributed Bragg reflector 62 is slightly lower than the reflectivity of the patterned distributed Bragg reflector 41 in step (2), which can be realized by reducing the number of dielectric film layers, such as using 21 layers of TiO ₂ /SiO ₂ stacked structure.

(6) Finally, the GaN-based epitaxial film is separated by inductively coupled plasma etching, and the preparation of the surface-emitting laser is completed, as shown in Figure 8; each laser can work independently, or it can be simultaneously Work.

By adopting the above method, simultaneous output of multiple wavelengths of the GaN base surface emitting laser can be realized. Its laser wavelength covers the entire visible light range and has great application value. It can be used in many fields such as space precise ranging, terahertz signal generator, optical mixing, laser spectroscopy, medical detection, augmented reality (AR) and three-dimensional imaging, and The device is easy to realize a two-dimensional array structure, which is conducive to large-scale industrial production.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (13)

1. a kind of design method of asymmetric quantum well active area, it is characterised in that the described method comprises the following steps：

(1) a number of SQW is used；

(2) careful design is carried out to position of the SQW in resonator so that SQW is placed in different cavity in resonator Mould corresponds to the anti-node location of light field, so that the coupling in SQW and resonator between different cavity mould light field reaches most simultaneously By force, the asymmetric quantum well active area is obtained, realizes that multiwavelength laser exports.

2. the method as described in claim 1, it is characterised in that in step (1), the SQW is asymmetric quantum well；Amount The quantity of sub- trap reaches two or more；SQW has different well layer thickness or different components；The SQW Well layer thickness and component determined by the optical maser wavelength of designed surface-emitting laser so that the amount of different-thickness or component The centre of luminescence wavelength of sub- trap is consistent with each optical maser wavelength.

3. the method as described in claim 1, it is characterised in that in step (2), SQW is placed in different cavity mould in resonator The method of the anti-node location of corresponding light field is as follows：First, the chamber length of careful design surface-emitting laser, obtains multiple positions and determines And meeting the chamber mould of demand, spatial distribution of the light field in resonator corresponding to each chamber mould is independent and determined；Then, root According to the chamber mould output wavelength λ of selected determination₁···λ_n, wherein n >=2 obtain these chamber moulds and correspond to light field in resonator Spatial distribution；Finally, the position of above-mentioned SQW is set, it is λ to make centre of luminescence wavelength₁···λ_nDifferent well layer thickness or The SQW of component corresponds to the anti-node location of light field in resonator respectively.

A kind of 4. preparation method of multi-wavelength GaN base asymmetric quantum well surface-emitting laser, it is characterised in that methods described bag Containing following steps：

(1) have in the Grown on Sapphire Substrates of cleaning outside the GaN base of asymmetric quantum well active area as claimed in claim 1 Prolong film；

(2) graphical distribution Bragg reflector is made on above-mentioned GaN base epitaxial film, then in its surface evaporation or sputtering First metal-containing layer；

(3) evaporate or sputter the second metal-containing layer in substrate surface；

(4) above-mentioned first metal-containing layer and the second metal-containing layer are brought into close contact, on-plane surface is carried out in vacuum or nitrogen atmosphere Metal bonding, Sapphire Substrate is then removed, obtain removing the GaN base epitaxial film after Sapphire Substrate；

(5) patterned metal electrode is made on the GaN base epitaxial film after above-mentioned removal Sapphire Substrate successively, is graphically divided Cloth Bragg mirror, complete the making of whole resonator；

(6) GaN base epitaxial film is separated, obtains the multi-wavelength GaN base asymmetric quantum well surface-emitting laser.

5. preparation method as claimed in claim 4, it is characterised in that in step (1), the preparation of the GaN base epitaxial film Method includes：Metal-organic chemical vapor extension MOCVD, molecular beam epitaxy MBE, hydride gas-phase epitaxy and magnetron sputtering.

6. preparation method as claimed in claim 4, it is characterised in that in step (1), the GaN base epitaxial film includes GaN Low temperature buffer layer, undoped with GaN layer, mix Si n-type GaN layer, InGaN/GaN asymmetric quantum wells active area, mix Mg's AlGaN layer, the p-type GaN layer for mixing Mg.

7. preparation method as claimed in claim 4, it is characterised in that described to make graphical distribution bragg in step (2) The method of speculum includes photoetching, stripping, corrosion and etching；The distribution Bragg reflector by two kinds of different refractivities Jie The plasma membrane superposition that interlocks forms；First metal-containing layer composition be Sn, Au, In, Cu, Pt, Cr, Ni, Ag, Ti in one kind or It is a variety of.

8. preparation method as claimed in claim 4, it is characterised in that in step (3), the substrate be silicon chip, carborundum or Copper sheet；The composition of second metal-containing layer is the one or more in Sn, Au, In, Cu, Pt, Cr, Ni, Ag, Ti.

9. preparation method as claimed in claim 4, it is characterised in that in step (4), obtain after removing Sapphire Substrate After GaN base epitaxial film, GaN base epitaxial film is transferred on substrate, then epitaxial film thickness be thinned, after making polishing N-type GaN surface roughnesses reach less than 10 nanometers.

10. preparation method as claimed in claim 4, it is characterised in that in step (5), the making patterned metal electrode, The method of graphical distribution Bragg reflector includes photoetching, stripping, corrosion and etching；The patterned metal electrode includes Ni/Au, Cr/Au, Ti/Au and Pt/Au；It is described that GaN base epitaxial film separation method is included into corrosion and sensing in step (6) Coupled plasma etch.

11. the asymmetric quantum well active area that a kind of method as described in any one such as claims 1 to 3 obtains.

12. the multi-wavelength GaN base asymmetric quantum well that the preparation method as described in a kind of any one such as claim 4~10 obtains Surface-emitting laser.

13. multi-wavelength GaN base asymmetric quantum well surface-emitting laser as claimed in claim 12 in space precision ranging, too Answering in hertz signal generator, photomixing, laser spectroscopy, medical treatment detection and augmented reality AR and three-dimensional imaging field With.