Surface emitting laser device and its manufacturing method

Abstract

To provide a surface emitting laser device which reduces internal stress and improves antistatic performance, and to provide a manufacturing method thereof.SOLUTION: A surface emitting laser device Z1 includes a first reflective layer 11, an active light emitting layer 12, a second reflective layer 13, and a current limiting structure 14. The active light-emitting layer is located between the first reflective layer and the second reflective layer for generating a laser beam. The current limiting structure has a PN junction or a PIN junction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a surface emitting laser device and a method for manufacturing the same, and more particularly to a vertical cavity chamber surface emitting laser device and a method for manufacturing the same. [Background technology]

[0002] In existing vertical cavity chamber surface emitting lasers, a high resistance oxide layer or an ion implantation region is usually formed in the top Bragg reflector by ion implantation or wet oxidation processes to limit the current flow area, but the cost of forming the current limiting oxide layer or ion implantation region by ion implantation or thermal oxidation processes is high and the hole size is not easily controlled.

[0003] Furthermore, there is a large difference in lattice mismatch and thermal expansion coefficient between the oxide layer and the semiconductor material forming the upper Bragg reflector, which makes the vertical resonant chamber surface emitting laser susceptible to destruction due to internal stress after annealing, resulting in a decrease in manufacturing yield. In addition, internal stress of the components shortens the component life and also reduces the optical output characteristics and reliability. Meanwhile, existing vertical resonant chamber surface emitting lasers are susceptible to internal damage due to electrostatic discharge (ESD) and surges. Summary of the Invention [Problem to be solved by the invention]

[0004] The technical problem to be solved by the present invention is to provide a surface-emitting laser device and a manufacturing method thereof in order to make up for the shortcomings of existing technology, thereby reducing the internal stress of the surface-emitting laser device and improving the antistatic performance of the surface-emitting laser device. [Means for solving the problem]

[0005] In order to solve the above technical problems, a surface emitting laser device is provided as a technical solution adopted in the present invention. The surface emitting laser device includes a first reflective layer, an active light emitting layer, a second reflective layer, and a current limiting structure. The active light emitting layer is located between the first reflective layer and the second reflective layer and generates a laser beam. The current limiting structure has a PN junction or a PIN junction.

[0006] In order to solve the above technical problems, another technical solution adopted in the present invention provides a surface emitting laser device. The surface emitting laser device includes a first reflective layer, an active light emitting layer, a second reflective layer, and a current limiting structure. The active light emitting layer is located between the first reflective layer and the second reflective layer and generates a laser beam. The current limiting structure includes a Zener diode.

[0007] In order to solve the above-mentioned technical problems, the present invention provides a method for manufacturing a surface emitting laser device, which includes the steps of forming a first reflective layer, forming an active light emitting layer on the first reflective layer, forming a current-limiting structure, and forming a second reflective layer, in which the current-limiting structure defines a boundary hole and has a PN junction or a PIN junction. Effect of the Invention

[0008] One beneficial effect of the present invention is that in the surface-emitting laser device and its manufacturing method, the reliability of the surface-emitting laser device or the antistatic performance of the surface-emitting laser device itself is improved by the technical solution that "the current-limiting structure has a PN junction or a PIN junction" or "the current-limiting structure has a Zener diode".

[0009] In order to better understand the characteristics and technical contents of the present invention, please refer to the following detailed description of the present invention and the accompanying drawings, which do not limit the protection scope of the present invention in any way. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view of a surface-emitting laser device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged schematic view of part II in FIG. [Diagram 3] FIG. 13 is a partially enlarged schematic view of a surface-emitting laser device according to another embodiment of the present invention. [Figure 4] 4 is a schematic cross-sectional view of a surface-emitting laser device according to a second embodiment of the present invention. FIG. [Diagram 5] FIG. 11 is a schematic cross-sectional view of a surface-emitting laser device according to a third embodiment of the present invention. [Figure 6] FIG. 11 is a schematic cross-sectional view of a surface-emitting laser device according to a fourth embodiment of the present invention. [Figure 7] FIG. 7 is an enlarged schematic view of a portion VII in FIG. [Figure 8] FIG. 13 is a partially enlarged schematic view of a surface-emitting laser device according to another embodiment of the present invention. [Figure 9] FIG. 11 is a schematic cross-sectional view of a surface-emitting laser device according to a fifth embodiment of the present invention. [Figure 10] 4 is a flowchart of a method for manufacturing a surface-emitting laser device according to an embodiment of the present invention. [Figure 11] FIG. 2 is a schematic diagram of the surface emitting laser device according to the embodiment of the present invention at step S10. [Figure 12] FIG. 2 is a schematic diagram of the surface emitting laser device according to the embodiment of the present invention at step S20. [Figure 13] FIG. 2 is a schematic diagram of the surface emitting laser device according to the embodiment of the present invention at step S30. [Figure 14] FIG. 2 is a schematic diagram of the surface emitting laser device according to the embodiment of the present invention at step S30. [Figure 15] FIG. 2 is a schematic diagram of the surface emitting laser device according to the embodiment of the present invention at step S40. [Figure 16] FIG. 2 is a schematic diagram of the surface emitting laser device according to the embodiment of the present invention at step S50. [Figure 17] 1 is a schematic diagram of a surface-emitting laser device according to another embodiment of the present invention at step S40. [Figure 18] 1 is a schematic diagram of a surface-emitting laser device according to another embodiment of the present invention at step S50. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] [First embodiment] 1 and 2, an embodiment of the present invention provides a surface-emitting laser device Z1. In the embodiment of the present invention, the surface-emitting laser device Z1 is a vertical chamber surface-emitting laser device. The surface-emitting laser device Z1 includes a first reflective layer 11, an active light-emitting layer 12, a second reflective layer 13, and a current-limiting structure 14. Specifically, in this embodiment, the surface-emitting laser device Z1 also includes a base 10. The first reflective layer 11, the active light-emitting layer 12, the second reflective layer 13, and the current-limiting structure 14 are all disposed on the base 10, and the active light-emitting layer 12 is located between the first reflective layer 11 and the second reflective layer 13.

[0012] The base 10 can be an insulating base or a semiconductor base. The insulating base is, for example, sapphire, and the semiconductor base is, for example, silicon, germanium, silicon carbide, or a III-V group semiconductor. The III-V group semiconductor is, for example, gallium arsenide (GaAs), indium phosphate (InP), aluminum nitride (AIN), indium nitride (InN), or gallium nitride (GaN). The base 10 also has an epitaxial surface 10a and a bottom surface 10b opposite to the epitaxial surface 10a.

[0013] The first reflective layer 11, the active light-emitting layer 12, and the second reflective layer 13 are located in succession on the epitaxial surface 10a of the substrate 10. In this embodiment, the first reflective layer 11, the active light-emitting layer 12, and the second reflective layer 13 have the same cross-sectional width as the active light-emitting layer 12.

[0014] The first reflective layer 11 and the second reflective layer 13 may be a distributed Bragg reflector (DBR) formed by alternately stacking two types of thin films having different refractive indices, and reflect and resonate a predetermined wavelength. In this embodiment, the material constituting the first reflective layer 11 and the second reflective layer 13 is a doped III-V compound semiconductor, and the first reflective layer 11 and the second reflective layer 13 have different conductivity types.

[0015] The active light emitting layer 12 is formed on the first reflecting layer 11 and serves to generate a laser beam L. In detail, the active light emitting layer 12 is located between the first reflecting layer 11 and the second reflecting layer 13, and is excited by electric power to generate an initial light flux. The initial light flux generated by the active light emitting layer 12 is reflected and resonated between the first reflecting layer 11 and the second reflecting layer 13 to amplify the gain, and finally emerges from the second reflecting layer 13 to generate a laser beam L.

[0016] The active light emitting layer 12 includes multiple film layers for forming multiple quantum wells. Specifically, trap layers and barrier layers are alternately stacked, and neither is doped. The materials of the trap layers and barrier layers are determined according to the wavelength of the laser beam L to be generated. For example, when the laser beam L to be generated is red, the material of the trap layer can be indium gallium phosphide (InGaP). When the laser beam L to be generated is near infrared light, the trap layers and barrier layers can be gallium arsenide layers and aluminum gallium arsenide (AlGaP), respectively. x Ga (1-x) When the laser beam L is blue light, the barrier layer and the trapping layer are a gallium nitride (GaN) layer and an indium gallium nitride (InGaN) layer, respectively.

[0017] Please refer to FIG. 1 and FIG. 2. The surface emitting laser device Z1 also includes a current limiting structure 14. And the current limiting structure 14 is located above or below the active light emitting layer 12. The current limiting structure 14 has a boundary hole 14H, which defines a current channel. It should be noted that as long as the current limiting structure 14 can define a current passing area, its position is not limited in the present invention. In this embodiment, the current limiting structure 14 is located in the second reflective layer 13 and connected to the active light emitting layer 12. As shown in FIG. 2, specifically, in this embodiment, a part of the second reflective layer 13 is filled in the boundary hole 14H and connected to the active light emitting layer 12. Since the second reflective layer 13 is a doped semiconductor material and has high conductivity, the part filled in the boundary hole 14H allows the current to pass.

[0018] As shown in FIG. 2, in this embodiment, the current-limiting structure 14 has at least one PN junction SA. In particular, the current-limiting structure 14 includes a first conductive type doped layer 141 and a second conductive type doped layer 142, and a PN junction SA is formed between the first conductive type doped layer 141 and the second conductive type doped layer 142. Specifically, the first conductive type doped layer 141 has a conductive type opposite to that of the first reflective layer 11, and the second conductive type doped layer 142 also has a conductive type opposite to that of the second reflective layer 13. For example, when the first reflective layer 11 is an N type, the second reflective layer 13 and the first conductive type doped layer 141 are a P type, and the second conductive type doped layer 142 is an N type. When the first reflective layer 11 is P-type, the second reflective layer 13 and the first conductive type doped layer 141 are N-type, and the second conductive type doped layer 142 is P-type.

[0019] 2, the current-limiting structure 14 is disposed with the first conductive type doped layer 141 facing the first reflective layer 11. Since the second reflective layer 13 and the second conductive type doped layer 142 have opposite conductive types, the second reflective layer 13 and the second conductive type doped layer 142 form another PN junction SB in the surface-emitting laser device Z1. In this manner, the current-limiting structure 14 of this embodiment has a Zener diode jointly formed by the first conductive type doped layer 141 and the second conductive type doped layer 142.

[0020] The material constituting the current-limiting structure 14 can be selected as a semiconductor material that does not absorb the laser beam L. In other words, the semiconductor material constituting the current-limiting structure 14 allows the laser beam L to pass through. When the wavelength of the laser beam L is λ (unit: nanometer) and the energy band gap of the semiconductor material constituting the current-limiting structure 14 is Eg, the energy band gap Eg and the wavelength of the laser beam L have a relational expression of Eg>(1240 / λ). For example, when the wavelength λ of the laser beam L is 850 nm, the energy band gap Eg of the current-limiting structure 14 should be larger than 1.46 eV. In this way, it is possible to avoid a decrease in the light emission efficiency of the surface-emitting laser device Z1 due to the current-limiting structure 14 absorbing the laser beam L. In a specific embodiment, the energy band gap of the semiconductor material constituting the current-limiting structure 14 is larger than the energy band gap of the semiconductor material constituting the active light-emitting layer 12 (trap layer).

[0021] In addition, in this embodiment, the crystal lattice constant of the material of the current-constraining structure 14 and the crystal lattice constant of the material of the active light-emitting layer 12 are matched with each other, which can reduce interface defects. In a better embodiment, the lattice mismatch between the material of the current-constraining structure 14 and the material of the active light-emitting layer 12 is less than 0.1%. Furthermore, since the current-constraining structure 14 in this embodiment is located in the second reflective layer 13, the lattice mismatch between the material of the current-constraining structure 14 and the material of the second reflective layer 13 is less than 0.1%.

[0022] Compared with the existing oxide layer, the current-limiting structure 14 of this embodiment has a small degree of lattice mismatch between the active light-emitting layer 12 and the second reflecting layer 13, so that the internal stress of the surface-emitting laser device Z1 can be reduced and the reliability of the surface-emitting laser device Z1 can be improved. In this embodiment, the total thickness of the current-limiting structure 14 is 10 nm to 1000 nm. Since the current-limiting structure 14, the active light-emitting layer 12 and the second reflecting layer 13 are all made of semiconductor materials, the difference in thermal expansion coefficient is small. This can prevent the surface-emitting laser element Z1 from cracking due to the difference in thermal expansion coefficient after annealing, and improve the processing yield.

[0023] 1, the surface-emitting laser device Z1 according to the embodiment of the present invention further includes a first electrode layer 15 and a second electrode layer 16. The first electrode layer 15 is electrically connected to the first reflective layer 11, and the second electrode layer 16 is electrically connected to the second reflective layer 13. In the embodiment of FIG. 1, the first electrode layer 15 and the second electrode layer 16 are respectively located on different sides of the base 10, but in other embodiments, the first electrode layer 15 and the second electrode layer 16 may be located on the same side of the base 10.

[0024] More specifically, in this embodiment, the first electrode layer 15 is disposed on the bottom surface 10b of the base 10. The second electrode layer 16 is located on the second reflective layer 13 and is electrically connected to the second reflective layer 13. A current path is defined between the first electrode layer 15 and the second electrode layer 16 through the active light-emitting layer 12. The first electrode layer 15 and the second electrode layer 16 can be a single metal layer, an alloy layer, or a laminate layer made of different metal materials.

[0025] 1, the second electrode layer 16 has an opening 16H that defines the light-emitting area A1, and the opening 16H corresponds to the boundary hole 14H of the current-limiting structure 14, allowing the laser beam L generated by the active light-emitting layer 12 to exit from the opening 16H. In a particular embodiment, the second electrode layer 16 has an annular portion, but the present invention does not limit the shape of the second electrode layer 16 in plan view. The material of the second electrode layer 16 may be gold, tungsten, germanium, palladium, titanium, or any combination thereof.

[0026] In addition, the surface-emitting laser device Z1 of this embodiment further includes a current propagation layer 17 and a protective layer 18. The current propagation layer 17 is located on the second reflective layer 13 and is electrically connected to the second electrode layer 16. In a specific embodiment, the material of the current propagation layer 17 is a conductive material, which is used to uniformly distribute the current injected from the second reflective layer 13 to the active light-emitting layer 12. In addition, the material of the current propagation layer 17 is a material through which the laser beam L can pass, which can be avoided from excessively sacrificing the light-emitting efficiency of the surface-emitting laser device Z1. For example, when the wavelength of the laser beam L is 850 nm, the material of the current propagation layer 17 can be a highly doped semiconductor material, such as highly doped indium phosphide, but the present invention is not limited thereto.

[0027] The protective layer 18 covers the current propagation layer 17 and the light emitting area A1 to prevent moisture from entering the surface emitting laser device Z1 and affecting the light emission characteristics or life of the surface emitting laser device Z1. In a specific embodiment, the protective layer 18 may be made of a moisture-resistant material such as silicon nitride, aluminum oxide, or a combination thereof, and the present invention is not limited to these examples. In this embodiment, the second electrode layer 16 is disposed on the protective layer 18 and connected to the second reflective layer 13 through the protective layer 18 and the current propagation layer 17, but the present invention is not limited thereto. In another embodiment, the current propagation layer 17 may be omitted.

[0028] At least a part of the Zener diode of the current-limiting structure 14 is located in the current path defined by the first electrode layer 15 and the second electrode layer 16 so as to block the current. In this way, when the surface-emitting laser device Z1 is biased by the first electrode layer 15 and the second electrode layer 16, the Zener diode of the current-limiting structure 14 is reverse-biased but does not break down. Therefore, the Zener diode does not conduct, and the current bypasses the current-limiting structure 14 and passes through the boundary hole 14H. This increases the current density injected into the active light-emitting layer 12.

[0029] However, when electrostatic discharge occurs, the Zener diode of the current-limiting structure 14 is made conductive, whether the electrostatic current is positive or negative. When the Zener diode is made conductive, the resistance is much lower than the resistance of the second reflective layer 13 in the boundary hole 14H, so most of the electrostatic current passes through the current-limiting structure 14 and does not pass through the boundary hole 14H. It is noteworthy that the occupancy rate of the bird's-eye area of ​​the current-limiting structure 14 is larger than that of the boundary hole 14H. When the Zener diode of the current-limiting structure 14 is made conductive, the electrostatic current flowing through the active light-emitting layer 12 is dispersed, the current density is reduced, and damage to the active light-emitting layer 12 can be avoided. As a result, the current-limiting structure 14 can provide electrostatic discharge protection for the surface-emitting laser device Z1.

[0030] In other words, in the surface-emitting laser device Z1 according to the embodiment of the present invention, the current-limiting structure 14 has a Zener diode, which not only defines a current channel but also provides electrostatic discharge protection for the surface-emitting laser device Z1 and improves reliability.

[0031] Please refer to FIG. 3. A partial enlarged view of a surface emitting laser device according to another embodiment of the present invention is shown. In this embodiment, the current limiting structure 14 has a PIN junction, and can achieve the same effect. In detail, the current limiting structure 14 in this embodiment includes a first conductive type doped layer 141, a second conductive type doped layer 142 and an intrinsic semiconductor layer 143.

[0032] The intrinsic semiconductor layer 143 is located between the first conductive type doped layer 141 and the second conductive type doped layer 142. The intrinsic semiconductor layer 143 is an undoped semiconductor layer, and the semiconductor material constituting the intrinsic semiconductor layer 143 can be the same as the semiconductor material constituting the first conductive type doped layer 141 (or the second conductive type doped layer 142), but the present invention is not limited thereto.

[0033] In this manner, when a bias is applied to the surface-emitting laser device Z1, it is considered that a reverse bias smaller than the breakdown voltage is applied to the second conductive type doped layer 142 and the first conductive type doped layer 141 of the current-limiting structure 14, and the current-limiting structure 14 is in a non-conductive state. Therefore, a current is only allowed to pass through the boundary hole 14H of the current-limiting structure 14.

[0034] When an electrostatic discharge occurs and the reverse bias applied to the current-limiting structure 14 exceeds the breakdown voltage, the current-limiting structure 14 becomes conductive, and most of the electrostatic current passes through the current-limiting structure 14. By providing an intrinsic semiconductor layer 143 between the first conductive type doped layer 141 and the second conductive type doped layer 142, the electrostatic discharge protection capability of the current-limiting structure 14 for the surface-emitting laser device Z1 can be further improved.

[0035] [Second embodiment] Please refer to Fig. 4. Fig. 4 is a schematic cross-sectional view of a surface-emitting laser device Z2 according to a second embodiment of the present invention. In the surface-emitting laser device Z2 of this embodiment, parts similar to those in the surface-emitting laser device Z1 of the first embodiment are numbered similarly, and similar parts are omitted.

[0036] In the surface-emitting laser device Z2 of this embodiment, the current-limiting structure 14 is disposed in the second reflective layer 13, but is not connected to the active light-emitting layer 12. It is noteworthy that in this embodiment, the position of the current-limiting structure 14 is set to be close to the active light-emitting layer 12 and far from the second electrode layer 16. In this way, the current injected into the active light-emitting layer 12 through the boundary hole 14H is concentrated, and the light-emitting efficiency of the surface-emitting laser device Z2 is improved. The current-limiting structure 14 has a structure shown in FIG. 2 or FIG. 3. In this embodiment, the current-limiting structure 14 is disposed such that the first conductive doped layer 141 faces the first reflective layer 11 and is connected to the lower part of the second reflective layer 13. In addition, the second conductive doped layer 142 of the current-limiting structure 14 is connected to the upper part of the second reflective layer 13, and a PN junction SB is formed between the second conductive doped layer 142 and the second reflective layer 13.

[0037] In this way, when bias is applied to the surface-emitting laser device Z1, a reverse bias voltage smaller than the breakdown voltage is applied to the second conductive type doped layer 142 and the first conductive type doped layer 141 of the current-limiting structure 14, which causes the current-limiting structure 14 to be in a non-conductive state. Therefore, the current is only allowed to pass through the boundary hole 14H of the current-limiting structure 14. In this way, the present invention does not restrict the location of the current-limiting structure 14 in the second reflective layer 13, as long as the current-limiting structure 14 limits the current and provides electrostatic discharge protection to the surface-emitting laser device Z2.

[0038] [Third embodiment] Please refer to Fig. 5. Fig. 5 is a schematic cross-sectional view of a surface-emitting laser device according to a third embodiment of the present invention. In the surface-emitting laser device Z3 of this embodiment, the same elements as those in the surface-emitting laser device Z1 of the first embodiment are assigned the same numbers, and the same parts will not be described repeatedly.

[0039] In the surface-emitting laser device Z3 of this embodiment, the current-limiting structure 14 is located between the active light-emitting layer 12 and the second reflective layer 13, but the current-limiting structure 14 is not located within the second reflective layer 13. In particular, the surface-emitting laser device Z3 of this embodiment further includes a current injection layer 19, which is located between the current-limiting structure 14 and the second electrode layer 16. In this embodiment, a part of the current injection layer 19 is filled in the boundary hole 14H of the current-limiting structure 14.

[0040] Also, in this embodiment, the material of the current injection layer 19 is a doped semiconductor material, and the current injection layer 19 and the second conductivity type doped layer 142 have opposite conductivity types. This forms another PN junction (not numbered) between the current injection layer 19 and the second conductivity type doped layer 142. In a specific embodiment, the semiconductor material of the current injection layer 19 is the same as the semiconductor material of the first conductivity type doped layer 141 of the current-constraining structure 14, although the invention is not limited thereto. In another embodiment, the current-constraining structure 14 is not connected to the active light-emitting layer 12, but is embedded within the current injection layer 19.

[0041] The second electrode layer 16 is electrically connected to the current injection layer 19 via the current propagation layer 17. Therefore, when the surface-emitting laser device Z1 is biased, a reverse bias smaller than the breakdown voltage is applied to the second conductive type doped layer 142 and the first conductive type doped layer 141 of the current-limiting structure 14, and the current-limiting structure 14 is in a non-conductive state. Therefore, a current is allowed only through the boundary hole 14H of the current-limiting structure 14.

[0042] Moreover, in this embodiment, the second reflective layer 13 is disposed on the current propagation layer 17 together with the second electrode layer 16. Furthermore, the second reflective layer 13 is located within the opening 16H defined by the second electrode layer 16. In other words, the second electrode layer 16 in this embodiment surrounds the second reflective layer 13. It is noteworthy that in this embodiment, the material constituting the second reflective layer 13 can include a semiconductor material, an insulating material, or a combination thereof. The present invention is not limited to whether the semiconductor material is an intrinsic semiconductor material or a doped semiconductor material. For example, the semiconductor material can be, for example, silicon, indium gallium aluminum arsenide (InGaAlAs), indium gallium arsenide phosphide (InGaAsP), indium phosphide (InP), indium aluminum arsenide (InAlAs), aluminum gallium arsenide (AlGaAs), aluminum gallium nitride (AlGaN), etc., and can be selected according to the wavelength of the laser beam L. The insulating material can be an oxide or a nitride, for example, silicon oxide, titanium oxide, aluminum oxide, etc., but the present invention is not limited thereto.

[0043] In this embodiment, the second reflective layer 13 may include multiple film layers, and each film layer may be made of a material selected from the above materials. For example, each film layer may be a titanium oxide layer and a silicon oxide layer, a silicon layer and an aluminum oxide layer, or a titanium oxide layer and an aluminum oxide layer, depending on the wavelength of the laser beam L. The present invention is not limited thereto.

[0044] Please refer to Figures 6 and 7. Figure 6 is a schematic cross-sectional view of a surface-emitting laser device according to a fourth embodiment of the present invention, and Figure 7 is an enlarged schematic view of part VII of Figure 6. The same or similar parts as those of the surface-emitting laser device Z4 of this embodiment and the surface-emitting laser device Z1 of the first embodiment have the same numbers and will not be described. In this embodiment, the current-limiting structure 14 can be located between the active light-emitting layer 12 and the first reflective layer 11. In detail, the current-limiting structure 14 is embedded in the first reflective layer 11 and connected to the active light-emitting layer 12.

[0045] 7, the current-limiting structure 14 includes a first conductive type doped layer 141 and a second conductive type doped layer 142, and a PN junction SA is formed between the first conductive type doped layer 141 and the second conductive type doped layer 142. In addition, the first conductive type doped layer 141 is disposed toward the first electrode layer 15, and the second conductive type doped layer 142 is disposed toward the second electrode layer 16. On this basis, in the first reflective layer 11, the current-limiting structure 14 of this embodiment includes a Zener diode jointly formed by the first conductive type doped layer 141 and the second conductive type doped layer 142.

[0046] In this embodiment, the second conductive type doped layer 142 is located between the first conductive type doped layer 141 and the active light emitting layer 12. The first conductive type doped layer 141 and the first reflective layer 11 have opposite conductive types, so another PN junction SC is formed between the first conductive type doped layer 141 and the first reflective layer 11. For example, if the first reflective layer 11 is N-type, the first conductive type doped layer 141 will be P-type, and the second conductive type doped layer 142 will be N-type. Also, the second conductive type doped layer 142 and the first reflective layer 11 may be made of the same or different materials, and the present invention is not limited thereto.

[0047] When bias voltage is applied to the surface-emitting laser device Z4, a reverse bias voltage smaller than the breakdown voltage is applied to the Zener diode of the current-limiting structure 14, and the current-limiting structure 14 is in a non-conducting state. Therefore, the current is only allowed to pass through the boundary hole 14H of the current-limiting structure 14. When an electrostatic discharge occurs, regardless of whether the electrostatic current is positive or negative, the Zener diode of the current-limiting structure 14 is conductive and allows most of the electrostatic current to pass through the current-limiting structure 14, thereby providing electrostatic protection to the surface-emitting laser device Z4.

[0048] Referring to Fig. 8, this is a partially enlarged schematic diagram of a surface-emitting laser device of another embodiment of the present invention. In this embodiment, the current-limiting structure 14 is located in the first reflective layer 11 and has a PIN junction, which can achieve the same effect. Specifically, the current-limiting structure 14 of this embodiment includes a first conductive type doped layer 141, a second conductive type doped layer 142 and an intrinsic semiconductor layer 143. The intrinsic semiconductor layer 143 is located between the first conductive type doped layer 141 and the second conductive type doped layer 142. The operation principle of the current-limiting structure 14 of this embodiment is similar to that of the embodiment of Fig. 3, and can also provide electrostatic protection.

[0049] Please refer to FIG. 9, which is a cross-sectional schematic diagram of a surface-emitting laser device according to a fifth embodiment of the present invention. The same or similar elements of the surface-emitting laser device Z5 of this embodiment and the surface-emitting laser device Z3 of the third embodiment have the same numbers, and the description will be omitted. In this embodiment, the current-limiting structure 14 is embedded in the first reflective layer 11, but is not connected to the active light-emitting layer 12. However, the position of the current-limiting structure 14 is relatively close to the active light-emitting layer 12 and is located far from the base 10. The current-limiting structure 14 may be configured as shown in FIG. 7 or FIG. 8. Specifically, if the first conductive doped layer 141 and the first reflective layer 11 have opposite conductive types and a PN junction is formed, the current-limiting structure 14 can be used to limit the current passing path and provide electrostatic protection for the surface-emitting laser device Z5.

[0050] Please refer to Figure 10. Figure 10 is a flow chart of a method for manufacturing a surface emitting laser device according to an embodiment of the present invention. In step S10, a first reflective layer is formed. In step S20, an active light emitting layer is formed on the first reflective layer. In step S30, a current constraining structure is formed on the active light emitting layer, where the current constraining structure defines a boundary hole and has a PN junction or a PIN junction. In step S40, a second reflective layer is formed. In step S50, a first electrode layer and a second electrode layer are formed.

[0051] The manufacturing method of the surface-emitting laser device provided in this embodiment can be used to manufacture the surface-emitting laser devices Z1-Z5 in the first to fifth embodiments. An example of manufacturing the surface-emitting laser device Z1 of the first embodiment will be described with reference to Figs. 11 to 16.

[0052] As shown in Fig. 11, a first reflective layer 11 is formed on a base 10. More specifically, the first reflective layer 11 is formed on an epitaxial surface 10a of the base 10. The material of the base 10 is as described above and will not be repeated here. The base 10 may have the same conductivity type as the first reflective layer 11.

[0053] 12, an active light-emitting layer 12 is formed on the first reflective layer 11. The active light-emitting layer 12 can be formed by alternately forming multiple trap layers and multiple barrier layers on the first reflective layer 11. In a specific embodiment, the first reflective layer 11 and the active light-emitting layer 12 can be formed on the epitaxial surface 10a of the base 10 by chemical vapor deposition.

[0054] Please refer to Figures 13 and 14. Figures 13 and 14 show a detailed flow of forming a current-constraining structure 14 on an active light-emitting layer. Referring to Figures 2 and 13, when it is necessary to form the current-constraining structure 14 shown in Figure 2, a first conductive type doped layer 141 and a second conductive type doped layer 142 can be sequentially formed on the active light-emitting layer 12. As shown in Figure 13, the first conductive type doped layer 141 and the second conductive type doped layer 142 can jointly form a stacked structure 14A.

[0055] 3, the first conductive type doped layer 141 may be formed first, the intrinsic semiconductor layer 143 may be formed, and then the second conductive type doped layer 142 may be formed. In this case, the first conductive type doped layer 141, the intrinsic semiconductor layer 143, and the second conductive type doped layer 142 may collectively form the stacked structure 14A.

[0056] 14, in this embodiment, a boundary hole 14H may be formed in the laminated structure 14A to expose a part of the active light-emitting layer 12. Furthermore, the boundary hole 14H can be formed in the laminated structure 14A through an etching process. Referring to FIG. 15, a second reflective layer 13 is formed on the current-limiting structure 14 and the active light-emitting layer 12. Specifically, when the second reflective layer 13 is formed, a part of the second reflective layer 13 is filled in the boundary hole 14H and connected to the active light-emitting layer 12.

[0057] 16, the surface-emitting laser device Z1 of the first embodiment of the present invention can be manufactured by forming a first electrode layer 15 on the bottom surface 10b of the base 10 and forming a second electrode layer 16 on the second reflective layer 13. In this embodiment, before forming the second electrode layer 16, the current propagation layer 17 and the protective layer 18 may be formed first.

[0058] In fabricating the surface-emitting laser device Z2 of the second embodiment, a part of the second reflective layer 13 may be formed on the active light-emitting layer 12 first, and then the current-limiting structure 14 may be formed to have the boundary hole 14H. Next, another part of the second reflective layer 13 is regrown on the current-limiting structure 14.

[0059] Referring to Fig. 17, this step follows the step of Fig. 14. The manufacturing method of the embodiment of the present invention further includes a step of forming a current injection layer 19 in the current-constraining structure 14. In this embodiment, the step of forming the current injection layer 19 is performed before the step of forming the second reflective layer 13. As shown in Fig. 17, the current injection layer 19 is formed in the boundary hole 14H of the current-constraining structure 14 and is connected to the active light-emitting layer 12. Then, a current propagation layer 17 and a second reflective layer 13 are formed on the current injection layer 19.

[0060] Referring to FIG. 18, the first electrode layer 15 is formed on the bottom surface 10b of the base 10, and the second electrode layer 16 is formed on the current propagation layer 17, so that the second electrode layer 16 is electrically connected to the current injection layer 19. The second electrode layer 16 has an opening 16H corresponding to the boundary hole 14H, and is disposed so as to surround the second reflective layer 13. In other words, the second reflective layer 13 is located within the opening 16H defined by the second electrode layer 16. In a specific embodiment, after the current propagation layer 17 is formed, the second reflective layer 13 can be formed first, and then the second electrode layer 16 can be formed. In another embodiment, the steps of forming the second reflective layer 13 and the second electrode layer 16 can be interchanged. By performing the above steps, the surface-emitting laser device Z3 of the third embodiment can be manufactured.

[0061] It should be noted that, in manufacturing the surface-emitting laser device Z4 of the fourth embodiment, the step (S30) of forming the current-limiting structure 14 can be performed before the step (S20) of forming the active light-emitting layer 12. In manufacturing the surface-emitting laser device Z5 of the fifth embodiment, a part of the first reflection layer 11 may be formed first, and then the current-limiting structure 14 having the boundary hole 14H may be formed. After that, another part of the first reflection layer 11 is regrown on the current-limiting structure 14.

[0062] [Beneficial Effects of the Embodiments] One beneficial effect of the present invention is that in the surface-emitting laser device and the manufacturing method thereof provided by the present invention, the surface-emitting laser devices Z1 to Z5 can have better light-emitting efficiency and high reliability due to the technical solution that "the current-limiting structure 14 has a PN junction or a PIN junction" or "the current-limiting structure 14 has a Zener diode".

[0063] More specifically, the current-limiting structure 14 includes a first conductive type doped layer 141 and a second conductive type doped layer 142. The second conductive type doped layer 142 has an opposite conductive type to the second reflective layer 13, and the first conductive type doped layer 141 of the current-limiting structure 14 faces the first reflective layer 11. When the surface-emitting laser device Z1-Z5 is biased, the second conductive type doped layer 142 and the first conductive type doped layer 141 of the current-limiting structure 14 are reverse-biased below the breakdown voltage, and the current-limiting structure 14 is in a non-conducting state. Therefore, a current is only allowed to pass through the boundary hole 14H of the current-limiting structure 14.

[0064] When an electrostatic discharge occurs, the current-limiting structure 14 becomes conductive, and most of the electrostatic current passes through the current-limiting structure 14. Therefore, the current-limiting structure 14 of the embodiment of the present invention can not only limit the current path, but also provide electrostatic discharge protection to the surface-emitting laser devices Z1-Z5.

[0065] Compared with the existing surface-emitting laser devices, in the surface-emitting laser devices Z1-Z5 of the embodiments of the present invention, the current-limiting structure 14 itself functions as an electrostatic protection structure, and there is no need to connect another diode in parallel for protection, which can reduce the cost and save the space in the circuit layout of electronic products.

[0066] In addition, since the first reflective layer 11, the current-limiting structure 14, the active light-emitting layer 12, and the second reflective layer 13 are all made of semiconductor materials, the difference in thermal expansion coefficient is small. This can prevent the surface-emitting laser devices Z1-Z5 from bursting due to the difference in thermal expansion coefficient after annealing, and improve the manufacturing yield. In the surface-emitting laser devices Z1-Z5 of the embodiment of the present invention, since there is no need to use an oxide layer, the step of lateral oxidation can be omitted in the manufacturing process of the surface-emitting laser devices Z1-Z5. Furthermore, there is no need to form a lateral groove in the surface-emitting laser devices Z1-Z5 of the embodiment of the present invention. This can further simplify the manufacturing process of the surface-emitting laser devices Z1-Z5 and reduce the manufacturing cost. In addition, when performing lateral oxidation, it is possible to prevent the inside of the surface-emitting laser devices Z1-Z5 from being invaded by water vapor, which affects the light output characteristics. Therefore, the surface-emitting laser devices Z1-Z5 of the embodiment of the present invention can have even higher reliability.

[0067] The contents disclosed above are merely preferred possible embodiments of the present invention, and do not limit the scope of the claims of the present invention. Therefore, all equivalent technical modifications made based on the contents of the specification and accompanying drawings of the present invention are intended to be included in the scope of the claims of the present invention. [Explanation of symbols]

[0068] Z1-Z5: Surface emitting laser device L: Laser beam 10: Bass 10a: Epitaxial surface 10b: Bottom 11: First reflective layer 12: Active light-emitting layer 13: Second reflective layer 14: Current limiting structure 141: First conductive doped layer 142: second conductive type doped layer 143: Intrinsic semiconductor layer 14H: Boundary Hole SA, SB, SC: PIN junction 15: First electrode layer 16: Second electrode layer 16H: Opening A1: Light-emitting area 17: Current propagation layer 18:Protective layer 19: Current injection layer 14A: Laminated structure S10~S50: Step

Claims

1. 1. A surface emitting laser device comprising a first reflective layer, an active light emitting layer, a second reflective layer and a current-constraining structure, the active light-emitting layer is disposed between the first reflective layer and the second reflective layer and generates a laser beam; the current limiting structure comprises a PN junction or a PIN junction; the current-constraining structure is located within the second reflective layer, and another PN junction is formed with the second reflective layer, the current-constraining structure includes a first conductivity type doped layer and a second conductivity type doped layer, the second conductivity type doped layer having an opposite conductivity type to the second reflective layer, and the current-constraining structure is oriented such that the first conductivity type doped layer faces the first reflective layer; A surface emitting laser device comprising:

2. 2. The surface emitting laser device of claim 1, wherein the current limiting structure includes a first conductive type doped layer, a second conductive type doped layer, and an intrinsic semiconductor layer, the intrinsic semiconductor layer being located between the first conductive type doped layer and the second conductive type doped layer to form a PIN junction.

3. 2. The surface-emitting laser device of claim 1, wherein the current-limiting structure has a boundary hole, a portion of the second reflective layer is filled into the boundary hole and connected to the active light-emitting layer, an energy band gap of a material constituting the current-limiting structure is larger than an energy band gap of a semiconductor material constituting the active light-emitting layer, and a total thickness of the current-limiting structure is at least 30 nm.

4. a current injection layer located between the current-constraining structure and the second reflective layer; 4. The surface-emitting laser device according to claim 3, wherein a portion of the current injection layer is filled into the boundary hole of the current limiting structure, and another PN junction is formed between the current injection layer and the current limiting structure.

5. 1. A surface emitting laser device comprising a first reflective layer, an active light emitting layer, a second reflective layer and a current-constraining structure, the active light-emitting layer is disposed between the first reflective layer and the second reflective layer and generates a laser beam; the current limiting structure comprises a PN junction or a PIN junction; 13. A surface-emitting laser device, comprising: a current-limiting structure located within the first reflective layer; and another PN junction formed between the current-limiting structure and the first reflective layer.

6. 1. A surface emitting laser device comprising a first reflective layer, an active light emitting layer, a second reflective layer, and a current-constraining structure, The active light emitting layer is located between the first reflective layer and the second reflective layer, and the current-constraining structure comprises a Zener diode. A surface emitting laser device comprising:

7. 7. The surface emitting laser device of claim 6, wherein the current-limiting structure is located between the active light emitting layer and the second reflective layer or between the active light emitting layer and the first reflective layer, the current-limiting structure having a first conductivity type doped layer and a second conductivity type doped layer to form the Zener diode, the second conductivity type doped layer having an opposite conductivity type to the second reflective layer, and the current-limiting structure is positioned such that the first conductivity type doped layer faces the first reflective layer.

8. a first electrode layer electrically connected to the first reflective layer; a second electrode layer between the first electrode layers defining a current path through the active light emitting layer; the second electrode layer has an opening corresponding to a boundary hole of the current-limiting structure, the opening being for defining a light-emitting region; 7. The surface-emitting laser device according to claim 6, wherein at least a portion of the Zener diode is located on the current path.

9. forming a first reflective layer; forming an active light-emitting layer on the first reflective layer; forming a current-limiting structure; forming a second reflective layer; Including, The current limiting structure defines a boundary hole and has a PN junction or a PIN junction. A method for manufacturing a surface emitting laser device.

10. 10. The method for manufacturing a surface emitting laser device according to claim 9, wherein the step of forming the current constraining structure further includes the steps of forming a first conductive type doped layer, forming a second conductive type doped layer, and forming the boundary hole in a laminate structure, wherein the first conductive type doped layer has an opposite conductivity type to the first reflective layer, and the first conductive type doped layer and the second conductive type doped layer jointly form the laminate structure.

11. 10. The method for manufacturing a surface-emitting laser device according to claim 9, wherein the step of forming the current-limiting structure further includes the steps of forming a first conductive type doped layer, forming an intrinsic semiconductor layer on the first conductive type doped layer, forming a second conductive type doped layer on the intrinsic semiconductor layer to form a stacked structure, and forming the boundary hole in the stacked structure, wherein the first conductive type doped layer has an opposite conductivity type to the first reflective layer.

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