A semiconductor laser chip structure
By etching into the semiconductor laser chip, the undoped upper waveguide layer is solved, and the effect of improving laser efficiency and reducing current is achieved.
Patent Information
- Application Number
- CN202420887111.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-26
- Publication Date
- 2025-04-11
- Estimated Expiration
- 2034-04-26
AI Technical Summary
Nitride semiconductor ultraviolet lasers have problems with high internal light absorption loss of the laser, resulting in a decrease in slope efficiency and an increase in threshold current.
In the semiconductor laser chip structure, the non-ridge region of the upper cladding layer, the electron barrier layer and the upper waveguide layer are etched to form an undoped upper waveguide layer, thereby reducing the diffusion of Mg impurities and impurity absorption loss.
Improves aging light fade, reduces the optical loss of the laser, improves the slope efficiency, quantum efficiency of the laser, and reduces the threshold current.
Smart Images
Figure CN222749870U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of semiconductor optoelectronic devices, in particular to a semiconductor laser chip structure. Background Art
[0002] Lasers are widely used in laser display, laser TV, laser projector, communication, medical treatment, weapons, guidance, ranging, spectral analysis, cutting, precision welding, high-density optical storage and other fields. There are many types of lasers, and the classification methods are also diverse, mainly including solid, gas, liquid, semiconductor and dye types of lasers; compared with other types of lasers, all-solid-state semiconductor ultraviolet lasers have the advantages of small size, high efficiency, light weight, good stability, long life, simple and compact structure, and miniaturization. There are major differences between lasers and nitride semiconductor light-emitting diodes: 1) Lasers are generated by stimulated radiation of carriers, the spectral half-width is small, the brightness is very high, and the output power of a single laser can be in the W level, while nitride semiconductor light-emitting diodes are spontaneous radiation, and the output power of a single light-emitting diode is in the mW level; 2) The current density of the laser is up to KA / cm 2 , which is more than 2 orders of magnitude higher than that of nitride light-emitting diodes, resulting in stronger electron leakage, more serious Auger recombination, stronger polarization effect, more serious electron-hole mismatch, and more serious efficiency attenuation Droop effect; 3) The light-emitting diode spontaneously radiates, without external influence, and is incoherent light that transitions from high energy level to low energy level, while the laser is stimulated transition radiation, and the energy of the induced photon should be equal to the difference in energy levels of the electron transition, generating photons and induced photons with identical coherent light; 4) The principles are different: the light-emitting diode is under the action of external voltage, and the electron-hole transition to the active layer or pn junction generates radiation recombination and luminescence, while the laser needs the lasing conditions to be met before it can be lased, and the carrier inversion distribution in the active area must be met. The stimulated radiation light oscillates back and forth in the resonant cavity, and the propagation in the gain medium amplifies the light, and the threshold condition is met so that the gain is greater than the loss, and finally the laser is output. Nitride semiconductor ultraviolet lasers have the following problems: internal light absorption losses in the laser include impurity absorption losses, carrier absorption losses, waveguide structure sidewall scattering losses, and quantum well absorption losses; optical waveguide impurity absorption losses are high, inherent carbon impurities in p-type semiconductors will compensate for acceptors and destroy the p-type, the p-type doping has a low ionization rate (less than 10%), and a large amount of unionized Mg acceptor impurities (more than 90%) will produce a self-compensation effect and cause an increase in internal optical losses, resulting in a decrease in the laser slope efficiency and an increase in the threshold current. Utility Model Content
[0003] In order to solve the above technical problems, the utility model provides a semiconductor laser chip structure, comprising a substrate, a lower cladding layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, and an upper cladding layer, which are arranged in sequence from bottom to top, and the upper waveguide layer comprises a first upper waveguide layer and a second upper waveguide layer; characterized in that, by photolithography and etching processes, the non-ridge regions of the upper cladding layer, the electron blocking layer and the upper waveguide layer are etched, the ridge is etched through the cladding layer and the electron blocking layer, and a portion of the upper waveguide layer is etched away, the thickness of the etched upper waveguide layer is 100 to 3000 angstroms, and the upper waveguide layer, the electron blocking layer and the upper cladding layer are etched away; a contact electrode is prepared above the ridge, and a passivation layer is plated on the sidewall of the ridge; the remaining thickness of the first upper waveguide layer is 100 to 3000 angstroms, and the first upper waveguide layer and the remaining second upper waveguide layer constitute the remaining upper waveguide layer.
[0004] Through the above technical scheme, the non-ridge area is changed from the Mg-doped upper confinement layer and the electron blocking layer to the non-Mg-doped upper waveguide layer, which reduces the non-radiative recombination center formed by the diffusion of Mg impurities to the quantum well during use and improves the aging light attenuation. At the same time, the non-Mg-doped upper waveguide layer can reduce the impurity absorption loss of unionized Mg impurities and the quantum well absorption loss light absorption, reduce the optical loss of the laser, improve the slope efficiency and quantum efficiency of the laser and reduce the threshold current.
[0005] Specifically, the thickness of the ridge is 2000 to 8000 angstroms; there are a first etching interface and a second etching interface on both sides of the ridge; the first etching interface and the second etching interface constitute the etching interface of the ridge; the etching angle between the etching interface and the upper waveguide layer is α, the etching angle between the etching interface and the electron blocking layer is β, and the etching angle between the etching interface and the upper cladding layer is γ, wherein 60°≤α≤β≤γ≤90°.
[0006] Specifically, the interface shape of the first etching interface has a function y=x 2 / e x Curve distribution; the interface shape of the second etched interface has a function y=x 2 e x Curved distribution.
[0007] Specifically, the interface shape of the first etching interface has a function y=x / l nx curve distribution; the interface shape of the second etching interface has a function y=xe x Curved distribution.
[0008] Specifically, the interface shape of the first etching interface has a function y=x -a (a>0) curve distribution; the interface shape of the second etching interface has the function y=x+e x Curved distribution.
[0009] Specifically, the interface shape of the first etching interface has a function y=sinx / x2 The first quadrant curve distribution; the interface shape of the second etched interface has the function y=sinx+e x Or y = e x -si nx curve distribution.
[0010] Specifically, the interface shape of the first etching interface has a first quadrant curve distribution of the function y=cosx / x; the interface shape of the second etching interface has a function y=e x -cosx or y = e x +cosx curve distribution.
[0011] Specifically, the interface shape of the first etching interface has a function y=Ax 3 +Bx 2 +Cx+D curve distribution, where A<0,4(B 2 -3AC)<0; the interface shape of the second etching interface has the function y=Ex 3 +Fx 2 +Gx+H curve distribution, where E>0,4(F 2 -3EG)<0.
[0012] Specifically, the width of the ridge is 0.5 to 500 microns; the contact electrode is any one or any combination of ITO, IZO, GTO, indium tin oxide, ZnO, Au, Ag, Al, Ti, Pt, Ni, Cr, Nb, Pd, Rh, Mo, Cu, AuSn, NiAu, Ti PtAu, TiAl TiAu, CrAl CrPtAu, ITO / NiAu, indium tin oxide / Ti PtAu; the passivation layer is any one or any combination of SiO2, SiNx, Ta2O5, Al2O3, BN, AlN, and AlON.
[0013] Specifically, the lower cladding layer, the upper waveguide layer, the active layer, the lower waveguide layer, the electron blocking layer, and the upper cladding layer are any one or any combination of GaN, InGaN, InN, AlInN, AlGaN, AlInGaN, AlN, GaAs, GaP, InP, AlGaAs, AlInGaAs, AlGaInP, InGaAs, InGaAsN, AlInAs, AlInP, AlGaP, InGaP, GaSb, InSb, InAs, InAsSb, AlGaSb, AlSb, InGaSb, AlGaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond; the thickness of the upper cladding layer is 1000 to 8000 angstroms, and the doping concentration is 1E18 to 5E20cm -3; The thickness of the electron blocking layer is 20 to 500 angstroms, and the doping concentration is 1E18 to 1E20 cm -3 ; the thickness of the upper waveguide layer is 500 to 5000 angstroms and is non-doped; the thickness of the lower waveguide layer is 500 to 5000 angstroms; the thickness of the lower cladding layer is 100 to 8000 nanometers; the substrate includes any one of sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, Mo, TiW, CuW, Cu, sapphire / AlN composite substrate, diamond, graphene, sapphire / SiNx, sapphire / SiO2 / SiNx composite substrate, sapphire / SiNx / SiO2 composite substrate, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrate.
[0014] Compared with the prior art, the beneficial effects of the utility model are as follows: by guiding the light field close to the active area, the side wall scattering loss of the waveguide structure is reduced, the light field leakage is suppressed, the light field distribution is improved, the light field limitation factor is increased, the horizontal lateral mode is controlled, a far-field ripple field image is formed and the laser focusing spot resolution is improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated into and constitute a part of this specification. The accompanying drawings illustrate the embodiments and are used together with the description to explain the principles of the utility model. It will be easy to recognize other embodiments and many expected advantages of the embodiments because they become better understood by reference to the following detailed description. Other features, objects and advantages of the present application will become more apparent by reading the detailed description of the non-limiting embodiments made with reference to the following drawings:
[0016] Figure 1 is a schematic structural diagram of a semiconductor laser chip structure according to an embodiment of the present application;
[0017] Figure 2 It is a structural TEM lens electron microscope image (ridge) of a semiconductor laser chip structure according to an embodiment of the present application;
[0018] Figure 3 It is a structural TEM lens electron microscope image (etching interface) of a semiconductor laser chip structure according to an embodiment of the present application;
[0019] Figure 4 This is a structural TEM lens electron microscope image (angle of etching interface) of a semiconductor laser chip structure according to an embodiment of the present application;
[0020] Figure 5It is a structural TEM lens electron microscope image (shape distribution of etching interface) of a semiconductor laser chip structure according to an embodiment of the present application;
[0021] Figure 6 It is a structural SIMS secondary ion mass spectrum of a semiconductor laser chip structure according to an embodiment of the present application;
[0022] Figure 7 It is a structural TEM lens electron microscope image (epitaxial structure) of a semiconductor laser chip structure according to an embodiment of the present application;
[0023] Figure 8 It is a structural TEM lens electron microscope image (epitaxial structure) of a semiconductor laser chip structure according to an embodiment of the present application;
[0024] Fig. 9 It is a structural TEM lens electron microscope image (epitaxial structure) of a semiconductor laser chip structure according to an embodiment of the present application;
[0025] Fig.10 It is a structural TEM lens electron microscope image (epitaxial structure) of a semiconductor laser chip structure according to an embodiment of the present application;
[0026] Fig.11 It is a structural TEM lens electron microscope image (epitaxial structure) of a semiconductor laser chip structure according to an embodiment of the present application;
[0027] Fig.12 This is a structural TEM lens electron microscope image (epitaxial structure) of a semiconductor laser chip structure according to an embodiment of the present application.
[0028] The meaning of the numbers in the figure are: 100, substrate; 101, lower cladding layer; 102, lower waveguide layer; 103, active layer; 104, upper waveguide layer; 104a, first upper waveguide layer; 104b, second upper waveguide layer; 105, electron blocking layer; 106, upper cladding layer; 107, contact electrode; 108a, first etching interface; 108b, second etching interface; 109, ridge; 110, passivation layer. DETAILED DESCRIPTION
[0029] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant utility model, rather than to limit the utility model. It is also necessary to explain that, for ease of description, only the parts related to the utility model are shown in the accompanying drawings.
[0030] like Figure 1As shown, the present application proposes a semiconductor laser chip structure, comprising: a substrate 100, a lower cladding layer 101, a lower waveguide layer 102, an active layer 103, an upper waveguide layer 104, an electron blocking layer 105, an upper cladding layer 106 and a contact electrode 107 stacked in sequence from bottom to top, the upper waveguide layer 104 comprises a first upper waveguide layer 104a and a second upper waveguide layer 104b; wherein the second upper waveguide layer 104b, the electron blocking layer 105 and the upper cladding layer 106 form a ridge 109; a contact point 107 is prepared above the ridge 109, and a first etching interface 108a and a second etching interface 108b formed by etching are provided on both sides of the ridge 109.
[0031] like Figure 2 and Figure 3 As shown, the microstructure of ridge 109 is observed at a scale of 1000 nm by using a lens electron microscope. The sidewalls of ridge 109 are coated with a passivation layer 110, and the thickness of ridge 109 is 2000 to 8000 angstroms. The ridge 109 has a first etching interface 108a and a second etching interface 108b on both sides. The first etching interface 108a and the second etching interface 108b constitute the etching interface of ridge 109.
[0032] In order to guide the light field close to the active area, reduce the side wall scattering loss of the waveguide structure, suppress the leakage of the light field, improve the light field distribution, increase the light field confinement factor, control the horizontal lateral mode, form a far-field ripple field image and improve the laser focusing spot resolution, the etching angle between the etching interface and the upper waveguide layer 104 is defined as α, the etching angle between the etching interface and the electron blocking layer 105 is defined as β, and the etching angle between the etching interface and the upper cladding layer 106 is defined as γ, and the etching angles α, β and γ satisfy: 60°≤α≤β≤γ≤90°.
[0033] In a specific embodiment, Figure 3 and Figure 4 As shown, the etching angle between the etching interface and the ridge 109 is 73.8 degrees. Meanwhile, in this embodiment, the etching angles α, β and γ satisfy 60°≤α≤β≤γ≤90°.
[0034] In a specific embodiment, Figure 5 As shown, the interface shape of the first etching interface 108a has a function y=x 2 / e x Curve distribution; the interface shape of the second etched interface 108b has a function y=x 2 e x curve distribution; in this embodiment, the angle between the tangent line of the first etched interface 108a and the horizontal plane of the first upper waveguide layer 104a first increases to 180° and then gradually decreases, and the angle between the tangent line of the second etched interface 108b and the horizontal plane of the first upper waveguide layer 104a gradually decreases.
[0035] In a specific embodiment, Figure 2 and Figure 3 As shown, the interface shape of the first etching interface 108a has a function y=x / l nx curve distribution; the interface shape of the second etching interface 108b has a function y=xe x Curved distribution.
[0036] The effects that can be achieved by adopting the technical means of this application are:
[0037]
[0038] In a specific embodiment, Figure 5 As shown, the interface shape of the first etching interface 108a has a function y=x -a (a>0) curve distribution; the interface shape of the second etched interface 108b has the function y=x+e x Curved distribution.
[0039] The effects that can be achieved by adopting the technical means of this application are:
[0040]
[0041] In a specific embodiment, Figure 5 As shown, the interface shape of the first etching interface 108a has a function y=s inx / x 2 The first quadrant curve distribution; the interface shape of the second etched interface 108b has the function y=sinx+e x Or y = e x -si nx curve distribution.
[0042] The effects that can be achieved by adopting the technical means of this application are:
[0043]
[0044] In a specific embodiment, Figure 5 As shown, the interface shape of the first etching interface 108a has a first quadrant curve distribution of the function y=cosx / x; the interface shape of the second etching interface 108b has a function y=e x -cosx or y = e x +cosx curve distribution.
[0045] The effects that can be achieved by adopting the technical means of this application are:
[0046]
[0047] In a specific embodiment, Figure 5 As shown, the interface shape of the first etching interface 108a has a function y=Ax 3+Bx 2 +Cx+D curve distribution, where A<0,4(B 2 -3AC)<0; the interface shape of the second etched interface 108b has a function y=Ex 3 +Fx 2 +Gx+H curve distribution, where E>0,4(F 2 -3EG)<0.
[0048] The effects that can be achieved by adopting the technical means of this application are:
[0049]
[0050] like Figure 6 As shown, the non-ridge region of the upper cladding layer 106, the electron blocking layer 105 and the upper waveguide layer 104 is etched by photolithography and etching processes, the ridge 109 is etched through the cladding layer and the electron blocking layer 105, and a portion of the upper waveguide layer 104 is etched away, and the thickness of the upper waveguide layer 104 etched away is 100 to 3000 angstroms, so that the non-ridge region is changed from the Mg-doped upper confinement layer and the electron blocking layer to the non-Mg-doped upper waveguide layer (from Figure 6 It can be seen from the corresponding area of 104 that the Mg concentration in this area decreases rapidly), reducing the diffusion of Mg impurities to the non-radiative recombination center formed by the quantum well during use, improving the aging light attenuation. At the same time, the non-Mg-doped upper waveguide layer can reduce the impurity absorption loss of unionized Mg impurities and the quantum well absorption loss light absorption, reducing the optical loss of the laser; improving the slope efficiency and quantum efficiency of the laser and reducing the threshold current. Figure 7 , Fig.11 and Fig.12 As shown, the width of the ridge 109 ranges from 0.5 to 500 microns.
[0051] Specifically, the lower cladding layer 101, the upper waveguide layer 104, the active layer 103, the lower waveguide layer 102, the electron blocking layer 105, and the upper cladding layer 106 are any one or any combination of GaN, InGaN, InN, Al InN, Al GaN, Al InGaN, Al N, GaAs, GaP, InP, AlGaAs, Al InGaAs, Al Ga InP, InGaAs, InGaAsN, Al InAs, Al InP, Al GaP, InGaP, GaSb, InSb, InAs, InAsSb, Al GaSb, Al Sb, InGaSb, Al GaAsSb, InGaAsSb, SiC, Ga2O3, BN, and diamond.
[0052] like Figure 7 , Fig.11 and Fig.12 As shown, the thickness of the upper cladding layer 106 ranges from 1000 to 8000 angstroms. Figure 6 As shown, the doping concentration of the upper cladding layer 106 is 1E18-5E20cm -3 .
[0053] like Figure 7 , Figure 8 , Fig.11 and Fig.12 As shown, the thickness of the electron blocking layer 105 ranges from 20 to 500 angstroms. Figure 6 As shown, the doping concentration of the electron blocking layer 105 is 1E18-1E20 cm -3 .
[0054] Due to the aforementioned etching of the upper waveguide layer 104, the upper waveguide layer is non-doped; and the thickness of the upper waveguide layer 104 is 500-5000 angstroms.
[0055] Specifically, the thickness of the lower waveguide layer 102 is 500-5000 angstroms.
[0056] Specifically, the thickness of the lower cladding layer 101 is 100-8000 nanometers.
[0057] Specifically, the substrate 100 includes any one of sapphire, silicon, Ge, SiC, AlN, GaN, GaAs, InP, InAs, GaSb, sapphire / SiO2 composite substrate, Mo, TiW, CuW, Cu, sapphire / AlN composite substrate, diamond, graphene, sapphire / SiNx, sapphire / SiO2 / SiNx composite substrate, sapphire / SiNx / SiO2 composite substrate, magnesium aluminum spinel MgAl2O4, MgO, ZnO, ZrB2, LiAlO2 and LiGaO2 composite substrates.
[0058] Specifically, the contact electrode 107 is any one or any combination of ITO, IZO, GTO, indium tin oxide, ZnO, Au, Ag, Al, Ti, Pt, Ni, Cr, Nb, Pd, Rh, Mo, Cu, AuSn, NiAu, TiPtAu, TiAl TiAu, CrAl CrPtAu, ITO / NiAu, indium tin oxide / TiPtAu; the passivation layer 110 is any one or any combination of SiO2, SiNx, Ta2O5, Al2O3, BN, AlN, AlON.
[0059] The effects that can be achieved by adopting the technical means of this application are:
[0060]
[0061] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.
Claims
1. A semiconductor laser chip structure, comprising a substrate, a lower cladding layer, a lower waveguide layer, an active layer, an upper waveguide layer, an electron blocking layer, and an upper cladding layer arranged in sequence from bottom to top, wherein the upper waveguide layer comprises a first upper waveguide layer and a second upper waveguide layer; characterized in that: The non-ridge regions of the upper cladding layer, the electron blocking layer and the upper waveguide layer are etched by photolithography and etching processes, the ridge is etched through the cladding layer and the electron blocking layer, and a portion of the upper waveguide layer is etched away, the thickness of the upper waveguide layer etched away is 100 to 3000 angstroms, and the remaining upper waveguide layer, the electron blocking layer and the upper cladding layer are etched away; a contact electrode is prepared above the ridge, and a passivation layer is plated on the sidewall of the ridge; the remaining thickness of the first upper waveguide layer is 100 to 3000 angstroms, and the first upper waveguide layer and the remaining second upper waveguide layer constitute the remaining upper waveguide layer.
2. A semiconductor laser chip structure as claimed in claim 1, characterized in that: The thickness of the ridge is 2000 to 8000 angstroms; the ridge has a first etching interface and a second etching interface on both sides; the first etching interface and the second etching interface constitute the etching interface of the ridge; the etching angle between the etching interface and the upper waveguide layer is α, the etching angle between the etching interface and the electron blocking layer is β, and the etching angle between the etching interface and the upper cladding layer is γ, wherein 60°≤α≤β≤γ≤90°.
3. A semiconductor laser chip structure as claimed in claim 2, characterized in that: The interface shape of the first etching interface has a function y=x 2 / e x Curve distribution; the interface shape of the second etching interface has a function y=x 2 e x Curved distribution.
4. A semiconductor laser chip structure as claimed in claim 2, characterized in that: The interface shape of the first etching interface has a function y=x / lnx curve distribution; the interface shape of the second etching interface has a function y=xe x Curved distribution.
5. A semiconductor laser chip structure as claimed in claim 2, characterized in that: The interface shape of the first etching interface has a function y=x -a (a>0) curve distribution; the interface shape of the second etching interface has the function y=x+e x Curved distribution.
6. A semiconductor laser chip structure as claimed in claim 2, characterized in that: The interface shape of the first etching interface has a function y=sinx / x 2 The first quadrant curve distribution; the interface shape of the second etching interface has the function y=sinx+e x Or y = e x -sinx curve distribution.
7. A semiconductor laser chip structure as claimed in claim 2, characterized in that: The interface shape of the first etching interface has a first quadrant curve distribution of function y=cosx / x; the interface shape of the second etching interface has a function y=e x -cosx or y = e x +cosx curve distribution.
8. A semiconductor laser chip structure as claimed in claim 2, characterized in that: The interface shape of the first etching interface has a function y=Ax 3 +Bx 2 +Cx+D curve distribution, where A<0,4(B 2 -3AC)<0; the interface shape of the second etching interface has a function y=Ex 3 +Fx 2 +Gx+H curve distribution, where E>0,4(F 2 -3EG)<0.
9. A semiconductor laser chip structure as claimed in claim 1, characterized in that: The width of the ridge is 0.5 to 500 micrometers.
10. The semiconductor laser chip structure according to claim 1, characterized in that: The thickness of the upper cladding layer is 1000 to 8000 angstroms, and the doping concentration is 1E18 to 5E20 cm -3 The thickness of the electron blocking layer is 20 to 500 angstroms, and the doping concentration is 1E18 to 1E20 cm -3 ; The thickness of the upper waveguide layer is 500 to 5000 angstroms and is non-doped; the thickness of the lower waveguide layer is 500 to 5000 angstroms; the thickness of the lower cladding layer is 100 to 8000 nanometers.