Light-emitting device

Abstract

Light-emitting device configured to emit radiation, comprising: a substrate (50); an epitaxic structure (20) comprising in succession a first DBR stack (21), a light-emitting stack (22), a second DBR stack (23) and several discrete first and second contact regions (241), wherein the light-emitting device emits coherent light having a far-field angle of less than 15 degrees, at a forward current between a laser threshold current and a saturation current therein, and incoherent light at a forward current less than the laser threshold current, wherein the epitaxial structure (20) is arranged on the substrate (50) and further comprises: several first radiation-emitting areas in a first column; and several second radiation-emitting areas in a second column; a conductive layer (60) on the epitaxial structure (20); wherein the contact areas (241) are arranged in a two-dimensional field and are configured to direct a spatially limited current in the light-emitting device to the several first radiation-emitting areas and the several second radiation-emitting areas; and wherein one of the several first contact areas includes a first latitude (w3') and one of the several second contact areas includes a second latitude (w3) that differs from the first latitude (w3').

Description

Technical field

[0001] The disclosure relates to a light-emitting device and in particular to a light-emitting device having the properties of a laser and a light-emitting diode (LED). Description of the state of the art

[0002] Light-emitting diodes (LEDs) are widely used as solid-state light sources. Compared to conventional incandescent lamps or fluorescent tubes, LEDs offer advantages such as lower power consumption and longer lifespan, and therefore LEDs are gradually replacing conventional light sources and are used in various fields such as traffic lights, backlighting modules, street lighting, and biomedical devices.

[0003] Fig. Figure 24 is a cross-sectional view showing a conventional surface emitter (VCSEL). A surface emitter (VCSEL) can emit coherent light in a direction perpendicular to an active region. A VCSEL comprises a structure having a substrate 300, a pair of DBR stacks 200, 210 on the substrate 300 with an interposed active region 230 where electrons and holes combine to generate light. A first electrode 240 and a second electrode 250 are provided to inject an electric current into the active region to generate light, and the light is emitted from an aperture on a top surface of the VCSEL.

[0004] The surface emitter can have an undercut passage 260 in one of the DBR stacks 210. The undercut passage 260 is formed by selectively etching away a circumferential portion of one of the layers in the DBR stack 210, thus creating an air gap in the DBR stack 210 that has a relatively low conductivity compared to the conductivity of the other layers.

[0005] WO 2014 / 087301 A1 concerns a lighting device for a camera. The lighting device comprises an inhomogeneous field of several apertures for radiating elements to illuminate the field of view of a camera more uniformly.

[0006] US 6 144 682 A relates to a layer structure for a single surface emitter. Summary of the invention

[0007] A technical object of the present invention is to provide a light-emitting device that eliminates at least one of the disadvantages of the prior art, at least partially.

[0008] This problem is solved by the light-emitting devices according to independent claim 1. Further embodiments are described in the dependent claims.

[0009] The present disclosure provides a light-emitting device. The light-emitting device is configured, among other things, to emit radiation and comprises: a substrate; an epitaxial structure on the substrate comprising, in sequence, a first DBR stack, a light-emitting stack, a second DBR stack, and a contact layer; an electrode; a current-blocking layer between the contact layer and the electrode; a first opening formed in the current-blocking layer; and a second opening formed in the electrode and within the first opening, wherein a portion of the electrode extends into the first opening and contacts the contact layer; and the light-emitting device is without an oxidized layer and an ion-implanted layer in the second DBR stack. Brief description of the drawings

[0010] The foregoing aspects and many of the associated benefits of this revelation will be more easily recognized when they are better understood by reference to the following detailed description together with the accompanying drawings, wherein: Fig. 1A a top view of the first embodiment of the light-emitting device is not in accordance with the invention; Fig. 1B is a cross-sectional view along an A-A' line, which is the first embodiment of the in Fig. 1A shows the light-emitting device; Fig. 2 shows a curve of the relationship between the emitted optical power and the forward current of the first embodiment of the light-emitting device; Fig. 3A to Fig. 4B the method for producing the in Fig. 1A and Fig. The light-emitting device shown in 1B is represented; Fig. 5A a top view of the second embodiment of the light-emitting device is not in accordance with the invention; Fig. 5B a cross-sectional view along an A-A' line of the in Fig. The light-emitting device shown in 5A is; Fig. 6 is a cross-sectional view which does not show the third embodiment of the light-emitting device according to the invention; Fig. Figure 7 is a cross-sectional view that does not show the fourth embodiment of the light-emitting device according to the invention; Fig. 8A a top view of the fifth embodiment of the light-emitting device is not in accordance with the invention; Fig. 8B a cross-sectional view along an A-A' line of the in Fig. The light-emitting device shown in 8A is; Fig. 9A a top view of the sixth embodiment of the light-emitting device is not in accordance with the invention; Fig. 9B a cross-sectional view along an A-A' line of the in Fig. The light-emitting device shown in 9A is; Fig. 10A a top view of the current barrier layer of the sixth embodiment of the in Fig. The light-emitting device shown in 9A is; Fig. Fig. 10B a cross-sectional view along an A-A' line of the in Fig. The light-emitting device shown in 10A is shown; Fig. 11A a top view of the seventh embodiment of the light-emitting device is not in accordance with the invention; Fig. 11B a cross-sectional view along an A-A' line of the in Fig. The light-emitting device shown in 11A is; Fig. 12 shows a curve of the relationship between the emitted optical power and the forward current of the seventh embodiment of the light-emitting device; Fig. 12B an enlarged detail of area I in Fig. 12A indicates; Fig. 16A to Fig. 16B the method for producing the in Fig. 11A and Fig. The light-emitting device shown in 11B represents the device shown; Fig. 17A a top view of the eighth embodiment of the light-emitting device is not in accordance with the invention; Fig. 17B is a cross-sectional view along an A-A' line, which is the eighth embodiment of the in Fig. The light-emitting device shown in 17A is shown; Fig. 18 is a cross-sectional view which does not show the ninth embodiment of the light-emitting device according to the invention; Fig. 19A to 19D the method for producing the in Fig. The light-emitting device shown in 18 is depicted; Fig. 20A a top view of the tenth embodiment of the light-emitting device is not in accordance with the invention; Fig. 20B is a cross-sectional view along an A-A' line, which is the tenth embodiment of the in Fig. The light-emitting device shown in 20A is shown; Fig. 21A a top view of the eleventh embodiment of the light-emitting device according to the invention; Fig. Fig. 21B is a cross-sectional view along an A-A' line, which is the eleventh embodiment of the in Fig. The light-emitting device shown in 21A is shown; Fig. 22 a top view of the twelfth embodiment of the light-emitting device, which is outside the scope of the invention; Fig. 23 a top view of the thirteenth embodiment of the light-emitting device, which is outside the scope of the invention; and Fig. Figure 24 is a cross-sectional view showing a conventional VCSEL (Virtual Virtual Surface Emitting Light Source). Detailed description of preferred embodiments

[0011] Exemplary embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. The following embodiments are given by illustration to assist those skilled in the art in fully understanding the spirit of the present disclosure. It is thus pointed out that the present disclosure is not limited to the embodiments given here and can be realized in various forms. Furthermore, the drawings are not precisely to scale, and components may be exaggerated with respect to width, height, length, etc. Here, similar or identical reference numerals will designate similar or identical components throughout the drawings.

[0012] In the present disclosure, unless specifically mentioned, the general term AlGaAs stands for Al x Ga (1-x )As, where 0 ≤ x ≤ 1; the general expression AlInP means Al x In( 1- x) P, where 0 ≤ x ≤ 1; the general expression AlGaInP means (Al y Ga (1-y) ) (1-x) In x P, where 0 ≤ x ≤ 1 , 0 ≤ y ≤ 1; the general expression AlGaN means Al x Ga (1-x) N, where 0 ≤ x ≤ 1; the general expression AlAsSb means AlAs (1-x) Sb x , where 0 ≤ x ≤ 1, and the general expression InGaP means In x Ga 1-x P, where 0 ≤ x ≤ 1. The element content can be adjusted for various purposes, such as, but not limited to, adjusting the energy gap or adjusting the peak wavelength or the dominant wavelength.

[0013] Fig. 1A is a top view of the first embodiment of the light-emitting device not according to the invention; Fig. 1B is a cross-sectional view along an A-A' line, representing the first embodiment of the in Fig. Figure 1A shows a light-emitting device. In the present embodiment, the light-emitting device comprises a substrate 10, an epitaxial structure 20 on the substrate 10, a current barrier layer 30, a first electrode 40, and a second electrode 50. The epitaxial structure 20 comprises, in sequence, a first DBR stack 21, a light-emitting stack 22, a second DBR stack 23, and a contact layer 24. The conductivity type of the first DBR stack 21 differs from that of the second DBR stack 23. In the present embodiment, the first DBR stack 21 is of the n type, and the second DBR stack 23 is of the p type. The current barrier layer 30 is located between the contact layer 24 and the first electrode 40. A first opening 31 is formed in the current barrier layer 30 to expose the contact layer 24, and the first opening 31 has a first maximum width w1.Part of the first electrode 40 fills the first opening 31 and directly contacts the contact layer 24. A second opening 25 is formed in the first electrode 40 to expose the contact layer 24 and has a second maximum width w2 smaller than the first maximum width w1. The second electrode 50 is located on the side of the substrate 10 opposite the epitaxial structure 20. The light-emitting device is configured to emit radiation R having a peak wavelength in the range of 600 nm to 1600 nm, and preferably in the range of 830 nm to 1000 nm.

[0014] As in Fig. As shown in Figure 1B, in the present embodiment the width of the substrate 10, the width of the epitaxial structure 20, and the width of the current barrier layer 30 are essentially equal. In the present embodiment, the first opening 31 has a circular shape, and the first maximum width w1 is the diameter of the circle. The shape of the first opening 31 is not limited to the present embodiment. The shape of the first opening 31 can be an ellipse, a rectangle, a square, a rhombus, or any other shape. The first maximum width w1 is in the range of 20 µm to 50 µm, but is not limited thereto. The current barrier layer 30 comprises an insulating material, aluminum oxide (AlO₂). x ), silicon dioxide (SiO₂) x ), silicon oxynitride (SiO₂) x N y ), silicon nitride (Si x N yThe barrier layer 30 may be epoxy, polyimide, octafluorocyclobutane, benzocyclobutene (BCB), or silicon. Preferably, the barrier layer 30 is substantially transparent to the radiation emitted by the light-emitting stack 22. The barrier layer 30 has a thickness greater than 100 nm and preferably less than 2 µm, and further preferably close to or equal to nλ / 4, where λ is the peak wavelength of the radiation emitted from the light-emitting stack 22, and n is an odd positive integer.

[0015] In the present embodiment, the second opening 25 has a circular shape, and the second maximum width w2 is the diameter of the circle. The shape of the second opening 25 is not limited to the present embodiment. The shape of the second opening 25 can be an ellipse, a rectangle, a square, a rhombus, or any other shape. Preferably, the shape of the second opening 25 is substantially the same as the shape of the first opening 31. Preferably, the first opening 31 and the second opening 25 have a common center. Further preferable are the first opening 31 and the second opening 25 being substantially concentric circles.

[0016] As in the Fig. 1A and Fig. As shown in Figure 1B, the first electrode is a continuous layer and comprises a bonding section 41 for bonding a wire, a current injection section 42 for injecting a current through the epitaxial structure 20, and a bridge section 43 connecting the bonding section 41 and the current injection section 42. The bonding section 41 is located on the current barrier layer 30. The current injection section 42 fills the first opening 31 and contacts the contact layer 24. In one embodiment, the current injection section 42 is in the form of a ring, such that the second opening 25 is formed within the current injection section 42. In particular, in the present embodiment, the current injection section 42 is separated from a side wall of the current barrier layer 30, and thus a gap is formed between the current injection section 42 and the side wall of the current barrier layer 30, the gap exposing part of the epitaxial structure 20, as shown in Figure 1B. Fig. 1A and Fig. Figure 1B shows that the first electrode 40 of the present embodiment covers less than 50% of the surface of the current barrier layer 30. The current barrier layer 30 between the bridge section 43 and the epitaxial structure 20 and between the bond section 41 and the epitaxial structure 20 serves to prevent current from flowing directly through the epitaxial structure 20 from the bond section 41 and the bridge section 43.

[0017] In the present embodiment, the light-emitting device is free of a high-resistance structure in the second DBR stack 23, wherein the high-resistance structure is a layer in the second DBR stack 23 directly beneath the first electrode 40 and is thus covered by the first electrode 40, and has a relatively low conductivity compared to the conductivity of the other layers in the second DBR stack 23 directly beneath and thus covered by the first electrode 40. In particular, the high-resistance structure is implemented as an oxidized layer, an ion-implanted layer, or a subterranean passage, as shown in Fig. Figure 24 shows. A further preference is a light-emitting device free of an oxidized layer, an ion-implanted layer, and an undercut passage in the second DBR stack 23 directly beneath the current-disconnect layer 30 and / or directly beneath the first electrode 40. That is, the conductivity of the section of the second DBR stack 23 directly beneath the first opening 31 as a whole is essentially the same as the conductivity of the section of the second DBR stack 23 covered by the current-disconnect layer 30 as a whole. Preferably, the second DBR stack 23 consists essentially of a group III-V semiconductor material, such as AlGaAs. The second DBR stack 23 is free of any oxides, such as aluminum oxide, that are intentionally formed, where aluminum oxide has the empirical formula Al a O bThe second DBR stack 23 has a conductivity of a certain magnitude, where a and b are natural numbers other than 0. Furthermore, the second DBR stack 23 is free of any conductivity-reducing ions intentionally formed to reduce the conductivity of a portion of the second DBR stack 23 by more than three orders of magnitude, and preferably more than five orders of magnitude, compared to the conductivity of the other, more conductive portion of the second DBR stack 23. The conductivity-reducing ions include Ar ions, He ions, or H ions. The second DBR stack 23 may include unavoidable ions present in the environment; however, since the unavoidable ions do not substantially alter the conductivity of the second DBR stack 23—for example, reducing the conductivity by no more than one order of magnitude compared to the conductivity of the more conductive portion of the second DBR stack 23—the unavoidable ions should not be considered in the present disclosure.In one embodiment, because the light-emitting device is free of an undercut passage in the second DBR stack 23, each layer of the second DBR stack 23 consists essentially of a Group III-V semiconductor material and is without an air gap in any layer of the second DBR stack 23.

[0018] When a current flows into the epitaxic structure 20, the current flows because the current injection section 42 in the first opening 31 directly contacts the contact layer 24 of the epitaxic structure 20, and because the bond section 41 and the bridge section 43 are separated and isolated from the epitaxic structure 20 by the current barrier layer 30, primarily by the section of the epitaxic structure 20 that is not covered by the current barrier layer 30 and directly contacts the current injection section 42. That is, the current density of the section of the second DBR stack 23 directly beneath the current barrier layer 30 is much lower than the current density of the section of the second DBR stack 23 that is not covered by the current barrier layer 30 when the current flows into the epitaxic structure 20.As a result, the section of the epitaxial structure 20 directly contacts the current injection section 42 and essentially directly below the first opening 31, functioning as a radiation-emitting region to generate the radiation R. The radiation R exits the light-emitting device through the first opening 31. In particular, the uppermost layer of the epitaxial structure 20, i.e., the contact layer 24 in the present embodiment, is the first layer in the epitaxial structure 20 to conduct a spatially confined current in the light-emitting device.

[0019] Fig. Figure 2 shows a curve illustrating the relationship between the emitted optical power and the forward current of the first embodiment of the light-emitting device. In the present embodiment, the light-emitting device has a forward voltage V. f , a laser threshold current I th and a saturation current I satup. The forward voltage V f This is where the light-emitting device begins to conduct a significant forward current, for example, 5 mA in the present embodiment. The laser threshold current I th The saturation current is the smallest current at which the radiation emitted from the radiation-emitting area I of the light-emitting device is dominated by stimulated emission rather than spontaneous emission, and therefore the radiation becomes coherent. sat is a current at which the radiation output no longer increases with an increasing forward current. The radiation emitted from the radiation-emitting region I of the light-emitting device of the present disclosure is incoherent light at an operating voltage V. op greater than a forward voltage V f the light-emitting device and a forward current smaller than the laser threshold current I thPreferably, the incoherent light has a far-field angle greater than 60 degrees when the light-emitting device is operated at a voltage greater than a forward voltage V. f the light-emitting device and an operating current smaller than the laser threshold current I th The radiation R emitted from the radiation-emitting area I of the light-emitting device is coherent light exhibiting a far-field angle of less than 15 degrees when the light-emitting device is operated at a forward current greater than the laser threshold current I. th and smaller than the saturation current I sat operates. In particular, when the light-emitting device operates on a forward current that is essentially equal to the laser threshold current I. thThe portion of the epitaxial structure 20 that is neither the radiation-emitting region I nor the portion of the epitaxial structure 20 covered by the first electrode 40 emits incoherent light R1, as it has a current density much lower than that of the radiation-emitting region I. The bond section 41 and the bridge section 43 shield the radiation emitted from the epitaxial structure 20.

[0020] In the present embodiment, the laser threshold current I th approximately 20 mA. The laser threshold current I th , the saturation current I sat and a difference between the laser threshold current I th and the saturation current I sat The first maximum width w1 of the first aperture 31 can be adjusted for different applications. For example, if a higher laser threshold current I is required. th , a higher saturation current I satand a higher difference between the laser threshold current I th and the saturation current I sat The first maximum width w1 can be larger if required. In particular, the laser threshold current I th and the first maximum width w1 is given by the following equation: 0.4w1(μm)−7≤Ith(mA)≤0.4w1(μm)+7

[0021] Table 1 shows far-field angles of the radiation from the light-emitting device at different forward currents. The far-field angle of this disclosure is defined as the divergence angle at full width and half the maximum intensity, in order to specify the beam divergence. Table 1. Vorwärtsstrom (mA) Fernfeldwinkel 20 65,6° 23 5,6° 25 5,8° 30 6,5° 40 7,9°

[0022] Table 1 shows that if a forward current is higher than the laser threshold current I th and lower than the saturation current I satThe far-field angle of the radiation is less than 15 degrees and preferably between 5 degrees and 15 degrees, and further preferable between 5 degrees and 13 degrees.

[0023] In the present disclosure, although the light-emitting device is free of a high-resistance structure comprising an oxidized layer and an ion-implanted layer in the second DBR stack 23, the light-emitting device, by encompassing the current-blocking layer 30 and the first electrode, which causes the top layer of the epitaxic structure 20, which is the first layer of the epitaxic structure, to conduct a spatially confined current in the light-emitting device, exhibits a far-field angle of less than 15 degrees when a forward current is applied between the laser threshold current I th and the saturation current I satIn addition, a conventional light-emitting device comprising a high-resistance structure, e.g., an oxidized layer, in the second DBR stack 23 exhibits a wide far-field angle during normal operation, particularly when operating under a higher forward current. However, the light-emitting device exhibits a far-field angle of less than 15 degrees when a forward current is applied in a range between the laser threshold current I th and the saturation current I sat The light-emitting device is applicable to sensors such as proximity sensors, night vision systems, or oximeters.

[0024] Fig. 3A to Fig. 4B describes the process for producing the in Fig. 1A and Fig. The light-emitting device shown in 1B represents the device shown; Fig. 3B is a cross-sectional view along the in Fig. 3A shown A-A' line; Fig. 4B is a cross-sectional view along the in Fig. 4A shows the A-A' line. The procedure includes these steps: a. Referring to Fig. 3A and Fig. 3B, Providing a substrate 10; b. Formation of an epitaxial structure 20 on the substrate 10 by epitaxial growth; c. Forming a current barrier layer 30 on the epitaxial structure by any suitable method such as sputtering or vapor deposition. d. Structuring the current barrier layer 30 by means of a lithographic mask to form a first opening 31 to expose part of the epitaxial structure 20, by any suitable method; e. Forming a metal layer (not shown) on the current barrier layer 30 and covering the first opening 31 as in Fig. 4A and Fig. 4B shown; f. Structuring the metal layer by means of a lithographic mask to form a first electrode 40, wherein the first electrode comprises a current injection section 42, a bond section 41 and a bridge section 43 connecting the bond section 41 and the current injection section 42, wherein the bond section 41 and the bridge section 43 are on the current barrier layer 30 and the current injection section 42 fills the first opening 31, a second opening 25 being formed in the current injection section 42 to expose the epitaxial structure 20; g. Forming a second electrode 50 on the side of the substrate 10 opposite the epitaxial structure 20 by any suitable method; and h. Cutting the structure formed in step g to obtain an individual finished light-emitting device, which is then Fig. 1A and Fig. 1B is shown.

[0025] The method of the present disclosure is free of a step for reducing the conductivity in a treated region in the second DBR stack 23, such as an oxidation step to oxidize at least one layer in the treated region of the second DBR stack 23, an ion implantation step to implant at least one conductivity-reducing ion into at least one layer in the treated region of the second DBR stack 23, and / or an etching step to selectively etch away a circumferential portion, i.e., the treated region, of at least one layer in the DBR stack 23 to form an undercut passage, such that the conductivity in the oxidized region, the ion-implanted region, or the undercut passage is as described in Fig. 24 is lower than that of the region of the second DBR stack 23, which is not the treated region. The oxidation step, the ion implantation step, and the step to etch one of the layers in the second DBR stack 23 are used to convert a portion of the second DBR stack 23 directly beneath the first electrode 40 into a substantially insulated region, thereby forming a high-resistance structure in the second DBR stack 23. The method of the present disclosure uses more than four different lithographic masks for the structuring process. In the present embodiment, the method uses only two different lithographic masks for the structuring process. As a result, the method for fabricating the light-emitting device is simple and cost-effective.

[0026] Fig. 5A is a top view of the second embodiment of the light-emitting device not according to the invention; Fig. 5B is a cross-sectional view along an A-A' line of the in Fig. 5A light-emitting device shown. The same reference numeral, whether assigned or appearing throughout the specification in different paragraphs or figures, should denote the same or equivalent structure, material, material composition, and manufacturing process wherever it is defined in the disclosure, unless specifically described otherwise. The light-emitting device according to the second embodiment of the present disclosure comprises substantially the same structure as the first embodiment, the difference being that the width of the current-blocking layer 30 is smaller than the width of the epitaxial structure 20. As a result, a circumferential section of the epitaxial structure 20 is exposed from a top view of the light-emitting device, separate from the current-blocking layer 30. In addition, the first electrode 40 has a shape different from that of the first embodiment.In particular, the first electrode 40 covers the entire side wall of the current barrier layer 30, which encloses the first opening 31, thus exposing only the contact layer 24 directly beneath the second opening 25. As a result, the epitaxial structure 20 directly contacts the current injection section 42 and essentially functions as a radiation-emitting region I directly beneath the first opening 31, and the radiation R exits the surface of the light-emitting device mainly through the second opening 25. Furthermore, the first electrode 40 covers more than 50% of the surface of the current barrier layer 30, and the first electrode 40 has a shape that is substantially the same as the shape of the current barrier layer 30. Preferably, the first electrode 40 covers more than 80%, and more preferably more than 90%, of the surface of the current barrier layer 30.A portion of the first electrode 40, located away from the second opening 25, serves to bond a wire. Because the first electrode 40 covers a large surface area of ​​the current barrier layer 30 and the entire side wall of the current barrier layer 30, which encloses the first opening 31, a forward current will then be present if it is higher than the laser threshold current I. th of the light-emitting device, an incoherent light emitted from the light-emitting stack 22 directly below the greater part of the first electrode 40 is shielded by the first electrode 40, while a coherent light emitted from the light-emitting stack 22 exits from the second opening 25. The method for manufacturing the light-emitting device, as in Fig. 5A and Fig. Figure 5B shows that the method for manufacturing the light-emitting device is essentially the same as shown in Figure 5B. Fig. 1A and Fig. 1B shown, except that the lithographic mask for structuring the metal layer is different and therefore the structure of the first electrode 40 in the second embodiment differs from the structure of the first electrode 40 in the first embodiment.

[0027] Fig. Figure 6 is a cross-sectional view showing the third embodiment of the light-emitting device not according to the invention. The same reference numeral, whether assigned or appearing throughout the specification in different paragraphs or figures, should denote the same or an equivalent structure, material, material composition, and manufacturing process wherever it is defined in the disclosure, unless specifically described otherwise.The light-emitting device according to the third embodiment of the present disclosure comprises essentially the same structure as the second embodiment, the difference being that a circumferential portion of the epitaxial structure 20 is removed by some suitable method to form a bead 26 having a width smaller than the width of the substrate 10 and comprising an exposed mesa-wall 261 closer to the second opening 25 compared to the outermost edge of the substrate 10. In particular, the current barrier 30 covers along the mesa-wall 261 and a top surface of the first DBR stack 21. In the present embodiment, the mesa-wall 261 of the bead 26 of the epitaxial structure 20 is protected by the current barrier 30. As a result, the reliability of the epitaxial structure 20 and the reliability of the light-emitting device are improved.The method for manufacturing the light-emitting device as described in . Fig. Figure 6 shows essentially the same method for manufacturing the light-emitting device as in Fig. 5A and Fig. Figure 5B shows the difference. The difference is that, prior to forming a current barrier layer 30 on the epitaxial structure 20, the method further comprises steps for structuring the epitaxial structure 20 by removing a circumferential portion of the second DBR stack 23, a circumferential portion of the light-emitting stack 22, and a portion of a circumferential portion of the first DBR stack 21 of the epitaxial structure 20 by any suitable method to form a bead containing a mesa-wall 261. In the present embodiment, the method of the present disclosure uses no more than three different lithographic masks for the structuring process. As a result, the method for fabricating the light-emitting device is simple and cost-effective.

[0028] Fig. Figure 7 is a cross-sectional view showing the fourth embodiment of the light-emitting device not according to the invention. The same reference numeral, whether assigned or appearing throughout the specification in different paragraphs or figures, should denote the same or an equivalent structure, material, material composition, and manufacturing process while defined once anywhere in the disclosure, unless specifically described otherwise. The light-emitting device according to the fourth embodiment of the present disclosure comprises substantially the same structure as the third embodiment, the difference being that the first electrode 40 covers the current-blocking layer 30 along the mesa wall 261, and thus the current-blocking layer 30 is located between the epitaxial structure 20 and the first electrode 40.The first electrode 40, which covers the current barrier layer 30 along the mesa wall 261, prevents radiation emitted from the light-emitting stack 22 from being emitted from the mesa wall 261. The method for fabricating the light-emitting device as in . Fig. Figure 7 shows essentially the same method for manufacturing the light-emitting device as shown in Fig. 6 shown, except that the lithographic mask for structuring the metal layer is different.

[0029] Fig. 8A is a top view of the fifth embodiment of the light-emitting device not according to the invention; Fig. 8B is a cross-sectional view along an A-A' line of the in Fig. Figure 8A shows a light-emitting device. The same reference numeral, whether assigned or appearing throughout the specification in different paragraphs or figures, should denote the same or an equivalent structure, material, material composition, and manufacturing process wherever it is defined in the disclosure, unless specifically described otherwise. The light-emitting device according to the fifth embodiment of the present disclosure comprises substantially the same structure as the fourth embodiment, the difference being that the first opening 31 is in the form of a ring with a circular cross-section defined by the current-blocking layer 30. The current-blocking layer 30 comprises an inner part 301, an outer part 302, and the first maximum width w1 is the diameter of the circle enclosed by the outer part 302.The first opening 31 separates the inner part 301 of the current barrier 30 from the outer part 302 of the current barrier 30 to protect the radiation-emitting region I. The current barrier 30 in the present embodiment has a thickness that is substantially equal to nλ / 4, where λ is the peak wavelength of the radiation emitted from the light-emitting stack 22, and n is an odd positive integer. The first electrode 40 fills the first opening 31, covers along the side wall of the inner part 301 of the current barrier 30, and is located on the circumferential part of the inner part 301 of the current barrier 30. The second opening 25 exposes the underlying inner part 301 of the current barrier 30. The method for manufacturing the light-emitting device as in . Fig. 8A and Fig. Figure 8B shows essentially the same method for manufacturing the light-emitting device as shown in Fig. 7 shown, except that the lithographic mask for structuring the current barrier layer 30 is different.

[0030] Fig. 9A is a top view of the sixth embodiment of the light-emitting device not according to the invention; Fig. 9B is a cross-sectional view along an A-A' line of the in Fig. Light-emitting device shown in 9A. Fig. Figure 10A shows a top view of the current barrier layer 30 of the sixth embodiment of the light-emitting device; Fig. 10B shows a cross-sectional view along an A-A' line of the in Fig. The light-emitting device shown in Figure 10A. The same reference numeral, whether assigned or appearing throughout the specification in different paragraphs or figures, should denote the same or an equivalent structure, material, material composition, and manufacturing process wherever it is defined in the disclosure, unless specifically described otherwise. The light-emitting device according to the sixth embodiment of the present disclosure comprises substantially the same structure as the fourth embodiment, the difference being that the light-emitting device of the present embodiment comprises multiple radiation-emitting regions I arranged in a two-dimensional field on a single chip. In particular, multiple first openings 31 are formed in the current-blocking layer 30 to expose the contact layer 24.The current barrier layer 30 is a continuous layer, as in . Fig. Figure 10A shows the first openings 31 separated from each other by the current barrier layer 30. Several second openings 25, arranged in a two-dimensional array, are formed and separated from each other in the first electrode 40, each being formed from the second openings 25 correspondingly within one of the first openings 31 to expose the contact layer 24, such that the corresponding first opening 31 and second opening 25 are concentric. The first electrode 40 is a continuous layer and has a bonding section 41, without any second openings 25 within it, for bonding a wire. A portion of the first electrode 40 fills the first openings 31, covers along the side walls of the first current barrier layer 30 that encloses the first openings 31, and directly contacts the contact layer 24 of the epitaxial structure 20.The area of ​​the epitaxial structure 20, which directly contacts the first electrode 40 and is essentially located directly beneath the first openings 31, functions as radiation-emitting regions I. The arrangement of the radiation-emitting regions I is not limited to the present embodiment; for example, the radiation-emitting regions I may be arranged in an offset arrangement, or the number of radiation-emitting regions I of two adjacent rows and / or columns may differ.

[0031] Fig. Figure 11A is a top view of the seventh embodiment of the light-emitting device in accordance with the present disclosure; Fig. 11B is a cross-sectional view along an A-A' line of the in Fig. Figure 11A shows a light-emitting device. The same reference numeral, whether assigned or appearing throughout the specification in different paragraphs or figures, should denote the same or an equivalent structure, material, material composition, and manufacturing process while defined once anywhere in the disclosure, unless specifically described otherwise. In the present embodiment, the substrate 10, the first DBR stack 21, the light-emitting stack 22, and the second DBR stack 23 are substantially the same as in the second embodiment. The difference is that the contact layer 24 has a first width w3, and the second DBR stack 23 has a second width w4 greater than the first width w3. The light-emitting device further comprises a conductive layer 60 covering the contact layer 24 and inserted between the first electrode 40 and the contact layer 24.The conductive layer 60 has a third width w5, which is substantially equal to the second width w4 of the second DBR stack 23. The first electrode 40 covers more than 50% of the surface of the conductive layer 60. Preferably, the first electrode 40 covers more than 80%, and further preferably more than 90%, of the surface of the conductive layer 60. The first electrode 40 has an outline substantially equal to the outline of the conductive layer 60. The first electrode 40 contacts the conductive layer 60 directly, instead of directly contacting the contact layer 24. The second DBR stack 23, the light-emitting stack 22, and the first DBR stack 21 directly below the contact layer 24 function as a radiation-emitting region I. The radiation R exits the light-emitting device through the second opening 25.

[0032] The second opening 25 is located directly above the contact layer 24 and exposes the underlying conductive layer 60. The ratio of the first width w3 of the contact layer 24 to the second maximum width w2 of the second opening 25 is in the range of 0.1 to 3, and is preferably in the range of 0.5 to 1.1, and further preferable in the range of 0.6 to 0.8. Because the ratio of the first width w3 to the second maximum width w2 is less than 1, the first electrode 40 is less likely to block the light generated from the radiation-emitting region I, and thus more light exits the second opening 25.

[0033] The conductivity of the section of the second DBR stack 23 directly beneath the contact layer 24 is essentially equal to the conductivity of the section of the second DBR stack 23 not covered by the contact layer 24. The conductive layer 60 has a thickness essentially equal to nλ / 4, where λ is the peak wavelength of the radiation emitted from the light-emitting stack 22, and n is an odd positive integer. The conductive layer 50 comprises transparent conductive metal oxide material, such as indium tin oxide (ITO), aluminum zinc oxide (AZO), SnCdO, antimony tin oxide (ATO), ZnO, Zn₂SnO₄ (ZTO), or indium zinc oxide (IZO). The conductive layer 60 is essentially transparent to the radiation emitted by the light-emitting stack 22.

[0034] When a current flows from the first electrode 40 into the epitaxial structure 20, because the contact resistance between the contact layer 24 and the second DBR stack 23 is relatively lower than the contact resistance between the conductive layer 60 and the epitaxial structure 20, the current flows mainly from the conductive layer 60 to the contact layer 24 and then into the epitaxial structure 20 mainly through the contact layer 24. That is, the current density of the section of the second DBR stack 23 directly beneath the contact layer 24 is much higher than the current density of the section of the second DBR stack 23 not covered by the contact layer 24. In particular, the uppermost layer of the epitaxial structure 20, in the present embodiment the contact layer 24, is the first layer in the epitaxial structure 20 to conduct a spatially confined current in the light-emitting device.

[0035] Fig. 12A is a curve of the emitted radiation versus the forward current of the light-emitting device of the seventh embodiment, wherein the ratio of the first width w3 of the contact layer 24 to the second maximum width w2 of the second opening 25 is approximately 1. Fig. 12B is a graphic showing an enlarged detail of area I in Fig. Figure 12A shows. In the present embodiment, the laser threshold current I th approximately 13 mA, and the saturation current I sat is approximately 79 mA. The laser threshold current I th , the saturation current I sat and a difference between the laser threshold current I th and the saturation current I sat The first width w3 of the contact layer 24 can be adapted for different applications; for example, if a higher laser threshold current I is required... th , a higher saturation current I th and a higher difference between the laser threshold current I thand the saturation current I sat The first width w3 must be larger. In particular, the laser threshold current I must be satisfied. th and the first width w3 the following equation: 0.4 w3(μm)−7≤Ith(mA)≤0.4 w3(μm)+7

[0036] In one embodiment, the radiation has a peak wavelength of approximately 850 ± 10 nm. In another embodiment, the radiation has a peak wavelength of approximately 940 ± 10 nm.

[0037] Table 2 shows far-field angles of the radiation having a peak wavelength of 850 ± 10 nm, emitted by the light-emitting device of the seventh embodiment at different forward currents. Table 2. Vorwärtsstrom (mA) Fernfeldwinkel 15 10,54° 18 10,90° 22 10,9°

[0038] Table 3 shows the far-field angle and radiation output of the radiation, which has a peak wavelength of 940 ± 10 nm, of the light-emitting device of the seventh embodiment at different forward currents. In the present embodiment, the laser threshold current I th approximately 13 mA, and the saturation current is approximately 80 mA. Table 3. injizierter Strom (mA) Fernfeldwinkel P0(mW) 15 9,61° 1,09 18 11,03° 1,95 22 11,19° 3,2

[0039] From Tables 2 and 3, if a forward current is higher than the laser threshold current I th and lower than the saturation current I sat The far-field angle of the radiation is less than 15 degrees and preferably between 5 and 15 degrees, and further preferable between 8 and 13 degrees.

[0040] In the present disclosure, although the light-emitting device is free of a high-resistance structure comprising an oxidized layer and an ion-implanted layer in the second DBR stack 23, by encompassing the contact layer 24 and the conductive layer 60, which causes the top layer of the epitaxic structure 20, which is the first layer in the epitaxic structure, to conduct a spatially confined current in the light-emitting device, the light-emitting device exhibits a far-field angle of less than 15 degrees when a forward current is applied in a range between the laser threshold current I th and the saturation current I sat is.

[0041] Fig. Sections 13A to 16B describe the process for producing the in Fig. 11A and Fig. The light-emitting device shown in Figure 11B is described. The method comprises these steps: a. Referring to Fig. 13A and Fig. 13B, Providing a substrate 10; b. Formation of an epitaxial structure 20 on the substrate 10 by epitaxial growth; c. Structuring the contact layer 24 by means of a lithographic mask; d. referring to Fig. 14A and Fig. 14B Forming a conductive layer 60 covering the structured contact layer 24 by any suitable method such as sputtering or vapor deposition; e. referring to Fig. 15A and Fig. 15B form a metal layer (not shown) on the conductive layer 60; f. Structuring the metal layer by means of a lithographic mask to form a first electrode 40 and a second opening 25 in the first electrode 40, wherein the first electrode 40 has a structure substantially complementary to the structure of the contact layer 24 and the second opening 25 is substantially directly above the contact layer 24; g. referring to Fig. 16A and Fig. 16B Removing a circumferential portion of the epitaxial structure 20 to form a bulge 26 encompassing an exposed mesa-wall 261 closer to the second opening 25 compared to the outermost edge of the substrate 10; h. Forming a second electrode 50 on the side of the substrate 10 opposite the epitaxial structure 20; and i. Cutting the structure formed in step h to obtain an individual completed light-emitting device, as in Fig. 11A and Fig. 11B is shown.

[0042] The method of the present disclosure is also free of a step for reducing the conductivity of a layer in the treated region in the second DBR stack 23, such as an oxidation step, an ion implantation step to implant at least one conductivity-reducing ion into at least one layer in the treated region of the second DBR stack 23, and / or an etching step to selectively etch away a circumferential portion, i.e., the treated region, of at least one layer in the DBR stack 23 to form an undercut passage, such that the conductivity in the oxidized region, the ion-implanted region, or the undercut passage is as described in Fig. The resistance of the second DBR stack 23, shown in Figure 24, is lower than that of the area not being treated. The oxidation step, the ion implantation step, and the etching step of one of the layers in the second DBR stack 23 are used to convert a portion of the second DBR stack 23 directly beneath the first electrode 40 into a substantially insulated region, thereby forming a high-resistance structure in the second DBR stack 23. Preferably, the method of the present disclosure uses no more than three different lithographic masks for the structuring process. As a result, the method for fabricating the light-emitting device is simple and cost-effective.

[0043] Fig. 17A is a top view of the eighth embodiment of the light-emitting device in accordance with the present disclosure; Fig. 17B is a cross-sectional view along line AA' of the in Fig. The light-emitting device shown in Figure 17A. The same reference numeral, whether assigned or appearing throughout the specification in different paragraphs or figures, should denote the same or an equivalent structure, material, material composition, and manufacturing process wherever it is defined in the disclosure, unless specifically described otherwise. The light-emitting device according to the eighth embodiment of the present disclosure comprises substantially the same structure as the seventh embodiment, the difference being that the light-emitting device further comprises a passivation layer 110 which substantially and conformally covers the epitaxial structure 20, the conductive layer 60, and the first electrode 40.The passivation layer 110 includes an opening 111 that exposes the underlying first electrode 40 and, at a distance from the contact layer 24, a wire bonded to it. The method for manufacturing the light-emitting device as in . Fig. 17A and Fig. Figure 17B shows essentially the same method for manufacturing the light-emitting device as in Fig. 16A and Fig. Figure 16B shows the difference. The difference is that, after the step of forming a bead 26 comprising an exposed mesa wall 261, the method further comprises steps of conformally forming a passivation layer 110 along the exposed mesa wall 261 of the epitaxial structure 20, along a side wall of the conductive layer 60, along a side wall of the first electrode 40, and covering the conductive layer 60 and the first electrode 40; then structuring the passivation layer 110 to form an opening 111 in the passivation layer 110 for exposing the underlying first electrode 40. The method of the present disclosure uses no more than four different lithographic masks for the structuring process. As a result, the method for fabricating the light-emitting device is simple and cost-effective.

[0044] Fig. Figure 18 is a cross-sectional view showing the ninth embodiment of the light-emitting device. The top view of the light-emitting device is essentially the same as in Figure 18. Fig. Figure 11A shows that the same reference numeral, whether assigned or appearing in different paragraphs or figures throughout the specification, should denote the same or an equivalent structure, material, material composition, and manufacturing process wherever it is defined in the disclosure, unless specifically described otherwise. The light-emitting device according to the eighth embodiment of the present disclosure comprises substantially the same structure as the seventh embodiment, the difference being that the light-emitting device of the present embodiment comprises a permanent substrate 90 and a bonding layer 100 between the permanent substrate 90 and the epitaxial structure 20. In the present embodiment, the permanent substrate 90 has a higher thermal conductivity than that of the substrate 10.The bonding layer 100 serves to connect the permanent substrate 90 and the epitaxial structure 20. Fig. Sections 19A to 19D describe the process for producing the in Fig. Figure 18 shows the light-emitting device. The method for manufacturing the light-emitting device as shown in Figure 18 is described below. Fig. Figure 18 shows essentially the same method for manufacturing the light-emitting device as in Fig. 11A and Fig. Figure 11B shows the difference. The difference is that the method, prior to structuring the contact layer 24, further includes the steps for bonding the epitaxial structure 20 to a temporary substrate 70 by means of a temporary bonding layer 80 as shown in Figure 11B. Fig. 19A shown in the present embodiment, wherein the temporary substrate 70 comprises glass; removal of the substrate 10 by any suitable method as in Fig. 19B shown; bonding of the epitaxial structure 20 to a permanent substrate 90 by a bonding layer 100 as in Fig. 19C shown; and removal of the temporary substrate 70 and the temporary bonding layer 80 as in Fig. Figure 19D is shown. In the present embodiment, the light-emitting device comprises the permanent substrate 90 with a higher thermal conductivity through the method, which includes the bonding steps. As a result, the light-emitting device achieves a higher output power.

[0045] Fig. 20A is a top view of the tenth embodiment of the light-emitting device in accordance with the present disclosure; Fig. 20B is a cross-sectional view along an A-A' line, which is shown in Fig. Figure 20A shows a light-emitting device. The same reference numeral, whether assigned or appearing throughout the specification in different paragraphs or figures, should denote the same or an equivalent structure, material, material composition, and manufacturing process wherever it is defined in the disclosure, unless specifically described otherwise. The light-emitting device according to the tenth embodiment of the present disclosure comprises substantially the same structure as the seventh embodiment, the difference being that the light-emitting device of the present embodiment comprises multiple radiation-emitting regions I arranged as an array on a single chip. In particular, the contact layer 24 comprises multiple discrete contact regions 241 arranged in a two-dimensional array, as shown in Figure 20A. Fig. Figure 20A shows that each contact area 241 has a first width w3. In the present embodiment, the first widths w3 of the contact areas 241 are essentially the same. The conductive layer 60 is a continuous layer and covers the several discrete contact areas 241, as shown in Figure 20A. Fig. Figure 20B shows the first electrode 40, which is located on the conductive layer 60 and is a continuous layer. Several second openings 25 are formed in the first electrode 40 and are separated from one another, each second opening being shaped to align with one of the contact areas 241. The second openings 25 expose the conductive layer 60. The ratio of the width of one of the contact areas 241 to the second width w2 of the second opening 25 is in the range of 0.1 to 3, and preferably in the range of 0.9 to 1.1. In the present embodiment, the ratios are substantially the same. The second DBR stack 23, the light-emitting stack 22, and the first DBR stack 21, which are directly beneath the contact areas 241 and exposed through the second openings 25, function as radiation-emitting areas I.The number of contact areas 241 and second openings 25 are not limited to the present embodiment, and the arrangement of the radiation-emitting areas I is not limited to the present embodiment; for example, the radiation-emitting areas I can be arranged in a staggered arrangement, or the number of radiation-emitting areas I of two adjacent rows and / or columns can be different. In particular, the uppermost layer of the epitaxial structure 20, in the present embodiment the contact layer 24, is the first layer in the epitaxial structure 20 to conduct a spatially limited current in the light-emitting device.

[0046] Fig. 21A is a top view of the eleventh embodiment of the light-emitting device according to the invention; Fig. 21B is a cross-sectional view along an A-A' line, which is shown in Fig. Figure 21A shows a light-emitting device. The same reference numeral, whether assigned or appearing throughout the specification in different paragraphs or figures, should denote the same or an equivalent structure, material, material composition, and manufacturing process wherever it is defined in the disclosure, unless specifically described otherwise. The light-emitting device according to the eleventh embodiment of the present disclosure comprises substantially the same structure as the tenth embodiment, and the difference is that the width w 3' at least one of the contact areas 241 differs from the width w3 of other contact areas, so that they have several different laser threshold currents I th exhibits. In the present embodiment, the widths w 3'The contact areas 241 in the middle column are smaller than the latitudes w3 of the other contact areas 241, as shown in Fig. Figure 21B shows that the difference between the width of one of the contact areas 241 in the middle column and the width of one of the other contact areas 241 in the other second columns is not less than 3 µm, preferably greater than 8 µm, and preferably less than 40 µm. The second openings 25 aligned with the contact areas 241 in the middle column are smaller than the other second openings 25, as shown in Figure 21B. Fig. Figure 21A shows the ratio of the width of the contact areas 241 to the second maximum width w2 of the corresponding second opening 25. This ratio is in the range of 0.1 to 3, and is preferably in the range of 0.5 to 1.1, and even more preferably in the range of 0.6 to 0.8. The light-emitting device comprises several different laser threshold currents I th . Each from the laser threshold currents Ith It serves to generate coherent light from one of the radiation-emitting regions I. In particular because the widths w 3' Since the contact areas 241 are smaller than the widths w3 of the other contact areas 241, the laser threshold current I th to emit coherent light from one of the radiation-emitting regions I in the middle slit smaller than the laser threshold current I th for emitting coherent light from one of the radiation-emitting regions I in the other two slits. As a result, in the present embodiment, a forward current greater than the laser threshold current I is achieved. th to emit coherent light from one of the radiation-emitting regions I in the middle slit and smaller than the laser threshold current I thTo emit coherent light from the radiation-emitting regions I in the other two columns, the radiation emitted from the radiation-emitting regions I in the middle column is coherent light, each exhibiting a far-field angle of less than 15 degrees, while the radiation emitted from the other radiation-emitting regions I is incoherent light, each exhibiting a far-field angle greater than 60 degrees. Therefore, the light-emitting device is suitable for applications requiring both far- and near-field characteristics, such as security cameras. The arrangement of the contact regions 241, which have different widths, is not limited to the present embodiment. For example, the contact regions 241, which have a width smaller than the others, can be arranged in the first column.Alternatively, the contact areas with a smaller width and the contact areas with a larger width can be arranged alternately in a row and / or a column, so that they are arranged in a staggered arrangement.

[0047] Fig. Figure 22 is a top view of the twelfth embodiment of the light-emitting device, which is not according to the invention. The same reference numeral, whether assigned or appearing in different paragraphs or figures throughout the specification, should denote the same or an equivalent structure, material, material composition, and manufacturing process wherever it is defined in the disclosure, unless specifically described otherwise. The light-emitting device according to the twelfth embodiment comprises substantially the same structure as the eleventh embodiment, and the difference is that the light-emitting device incorporates several laser threshold currents I th comprises those that are essentially the same. Each from the laser threshold currents I thThis serves to generate coherent light from one of the radiation-emitting regions I. By using a different layout of the first electrode 40 to control different amounts of current injected into different contact regions 241, one of the contact regions 241 draws more current compared to the current drawn to the other contact regions 241 when a current flows into the light-emitting device. In particular, in the present embodiment, each width of the contact regions 241 in the central column is substantially the same as each width of the other contact regions 241. Each second opening 25, aligned with the contact region 241 in the central column, has a width substantially the same as each width of the other second openings 25. The first electrode 40 on the conductive layer 60 has a different layout compared to the first electrode 40 as shown in Fig. Figure 21A shows the first electrode 40 having a bonding section 41, several first extensions 44, and second extensions 45. The bonding section 41 serves to bond a wire to it. Each first extension 44 surrounds one of the second openings 25. Each of the second extensions 45 extends substantially and perpendicularly from the bonding section 41 and is connected to at least three of the first extensions 44. In the first embodiment, each width of the first extension 44 is substantially equal to one. Each width of the second extension 45 is substantially equal to one. The first extensions 44 surrounding the second openings 25 in the middle column are connected to two second extensions 45, while the first extensions 44 surrounding the second openings 25 in the other two columns are connected to only one second extension 45.As a result, when the light-emitting device is driven, each of the contact areas 241 in the middle column draws more current compared to the current drawn to the other contact areas 241. When the forward current passing through each contact area in the middle column exceeds the laser threshold current I. th When the corresponding radiation-emitting regions I are reached, the forward current passing through each contact region in the other two slits is still smaller than the laser threshold current I. thof the corresponding radiation-emitting regions I. As a result, the radiation emitted from the radiation-emitting regions I in the middle column is coherent light, each exhibiting a far-field angle of less than 15 degrees, while the radiation emitted from the other radiation-emitting regions I of the columns is incoherent light, each exhibiting a far-field angle greater than 60 degrees. Therefore, the light-emitting device is suitable for applications requiring both far- and near-field characteristics, such as security cameras. In another embodiment, to obtain the same result, the width of one of the first extensions 44 in the middle column can be greater than the width of one of the first extensions 44 in the other two columns.In another embodiment, to achieve the same result, the width of the second extension 45 in the middle column can be greater than the width of one of the second extensions 45 in the other two columns, instead of comprising two second extensions 45 connected to the first extensions 44 in the middle column. The arrangement of the first extensions 44 and the second extensions 45 is not limited to the present embodiment. For example, the first extensions 44 surrounding the second openings 25 in the first column can also be connected to two second extensions 45, and the widths of the first extensions 44 and the widths of the second extensions 45 can be modified accordingly.

[0048] Fig. Figure 23A is a top view of the thirteenth embodiment of the light-emitting device, which is not according to the invention. The same reference numeral, whether assigned or appearing in different paragraphs or figures throughout the specification, should denote the same or an equivalent structure, material, material composition, and manufacturing process wherever it is defined in the disclosure, unless specifically described otherwise. The light-emitting device according to the thirteenth embodiment of the present disclosure comprises substantially the same structure as the twelfth embodiment, the difference being that the first electrode 40 has a different layout on the conductive layer 60.The first electrode 40 includes a third extension 46, which has a width greater than the width of the first extension 44 and the width of the second extension 45. As a result, the third extension 46 covers a larger area of ​​the circumferential portion of the second openings 25 in the central column compared to the area of ​​the circumferential portion of the second openings 25 covered by the first extensions 44 and the second extensions 45 in the other two columns. Consequently, the contact area between the conductive layer 60 and the first electrode 40 surrounding the second openings 25 in the central column is larger than the contact area between the conductive layer 60 and the first electrode 40 surrounding the other second openings 25.Therefore, when the light-emitting device is activated, each of the contact areas 241 in the middle column draws more current compared to the current drawn to the other contact areas 241. When the forward current passing through each contact area 241 in the middle column exceeds the laser threshold current I. th When the corresponding radiation-emitting regions I are reached, the forward current passing through each contact region in the other two slits is still smaller than the laser threshold current I. thof the corresponding radiation-emitting regions I. As a result, the radiation emitted from the radiation-emitting regions I in the middle slit is coherent light, each exhibiting a far-field angle of less than 15 degrees, while the radiation emitted from the other radiation-emitting regions I of the slits is incoherent light, each exhibiting a far-field angle greater than 60 degrees. Therefore, the light-emitting device is suitable for applications requiring both far- and near-field characteristics, such as security cameras. The layout of the first extensions 44 and the second extensions 45 is not limited to the present embodiment. For example, the first electrode 40 can cover a larger area of ​​the circumferential portion of the second openings 25 in the first slit instead of in the middle slit.

[0049] The light-emitting stack 22 comprises an active region comprising a single heterostructure (SH), a double heterostructure (DH), or a multi-quantum well (MQW) structure. Preferably, the active region comprises a multi-quantum well (MQW) structure consisting of alternating well layers and barrier layers. The band gap of each barrier layer is larger than the band gap of any of the well layers. The peak wavelength of the light emitted from the active region can be modified by adjusting the thickness and material of the well layers. Preferably, the material of the well layers comprises a group III-V semiconductor material such as AlGaAs. The material of the barrier layers comprises a group III-V semiconductor material such as AlGaAs.The light-emitting stack 22 can further include a spacer layer between the active region and the first DBR stack 21 and / or between the active region and the second DBR stack 23 to adjust the overall thickness of the light-emitting stack 22 to essentially satisfy a thickness equal to nλ / 2, where λ is the peak wavelength of the radiation emitted from the light-emitting stack 22 and n is a positive integer. The spacer layer material comprises a group III-V semiconductor material such as AlGaAs.

[0050] The first DBR stack 21 and the second DBR stack 23 comprise several alternating semiconductor layers with high and low refractive indices. The material of the first DBR stack 21 and the second DBR stack 23 comprises a group III-V semiconductor material such as Al x Ga (1-x) As / Al y Ga (1-y)As, where x is different from y, and the content of Al and Ga can be adjusted to reflect a predetermined wavelength range. Each semiconductor layer has a thickness substantially equal to λ / 4n, where λ is the peak wavelength of the radiation emitted from the light-emitting stack 22, and n is the refractive index of the layer. The first DBR stack 21 has a reflectivity of over 99% at the peak wavelength. The second DBR stack 23 has a reflectivity of over 98% at the peak wavelength. Preferably, the reflectivity of the first DBR stack 21 is higher than that of the second DBR stack 23. The number of pairs in the first DBR stack 21 is greater than the number of pairs in the second DBR stack 23, where a high-refractive-index semiconductor layer and a low-refractive-index semiconductor layer are considered as a pair.Preferably, the number of pairs in the first DBR stack 21 is greater than 15, and even more preferably greater than 30, and less than 80. The number of pairs in the second DBR stack 23 is greater than 15, and even more preferably greater than 20, and less than 80.

[0051] In the present embodiment, the substrate 10 provides a top surface for the epitaxial growth of the epitaxial structure 20. The substrate 10 has a thickness sufficient to support the layers or structures grown on it. Preferably, the substrate 10 has a thickness not less than 100 µm, and preferably not greater than 250 µm. The substrate 10 is a single crystal and comprises a semiconductor material, for example, a group III-V semiconductor material or a group IV semiconductor material. In one embodiment, the substrate 10 comprises a group III-V semiconductor material of n-type or p-type. In the present embodiment, the group III-V semiconductor material comprises n-type GaAs. The n-type dopant comprises Si.

[0052] The permanent substrate 80 is electrically conductive to conduct a current flowing between the first electrode 40 and the second electrode 50. The permanent substrate 80 has a thickness sufficient to support the layers or structures on it, for example, greater than 100 µm. The substrate comprises a conductive material including Si, Ge, Cu, Mo, MoW, AlN, ZnO, or CuW. Preferably, the permanent substrate 80 comprises Si or CuW.

[0053] The first electrode 40 and the second electrode 50 serve to electrically connect to an external power source and to conduct a current between them. The material of the first electrode 40 and the second electrode 50 comprises transparent conductive material or metallic material, wherein the transparent conductive material comprises transparent conductive oxide, and wherein the metallic material comprises Au, Pt, GeAuNi, Ti, BeAu, GeAu, Al or ZnAu, Ni.

[0054] The first electrode 40 forms a low-resistance or ohmic contact with the second DBR stack 23 via the contact layer 24, wherein the resistance between the first electrode 40 and the second DBR stack 23 is less than 10 -2 The conductivity type of the contact layer 24 is the same as that of the second DBR stack 23. In one embodiment, the contact layer 24 is of the p-type and exhibits a high p-type impurity concentration, such as greater than 10. 18 / cm 3 and preferably larger than 10 19 / cm 3 and further preferable between 1 × 10 19 / cm 3 and 5 × 10 22 / cm3, both inclusive. The contact layer material comprises a group III-V semiconductor material such as GaAs or AlGaAs.

[0055] The bonding layer 100 and / or the temporary bonding layer 80 comprises transparent conductive oxide, metal material, insulating oxide, or polymer. The transparent conductive oxide includes indium tin oxide (ITO), indium oxide (InO), tin oxide (SnO), cadmium tin oxide (CTO), antimony tin oxide (ATO), aluminum zinc oxide (AZO), zinc tin oxide (ZTO), gallium-doped zinc oxide (GZO), tungsten-doped indium oxide (IWO), zinc oxide (ZnO), or indium zinc oxide (IZO). The metal material includes In, Sn, Au, Ti, Ni, Pt, W, or alloys thereof. The insulating oxide includes aluminum oxide (AlO₂). x ), silicon dioxide (SiO₂) x ) or silicon oxynitride (SiO₂) x N y The polymer comprises epoxy, polyimide, octafluorocyclobutane, benzocyclobutene (BCB), or silicone. The bond layer has a thickness in the range of 400 nm to 5000 nm.

[0056] The method for performing epitaxial waxing includes, but is not limited to, metal-organic chemical vapor deposition (MOCVD), hydride gas phase epitaxy (HVPE), molecular beam epitaxy (MBE), or liquid phase epitaxy (LPE).

[0057] In accordance with a further embodiment outside the invention, the structures in the embodiments of the present disclosure can be combined or modified. For example, the light-emitting device as described in Fig. 1A and Fig. Figure 1B shows the passivation layer.

[0058] The foregoing description of preferred and other embodiments of the present disclosure is not intended to limit or restrict the scope of protection or the applicability of the concepts of the invention conceived by the applicant. In return for the disclosure of the concepts of the invention contained herein, the applicant requests all patent rights permitted by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they fall within the scope of protection of the following claims.

Claims

[1] Light-emitting device configured to emit radiation, comprising: a substrate (50); an epitaxic structure (20) comprising in succession a first DBR stack (21), a light-emitting stack (22), a second DBR stack (23) and several discrete first and second contact regions (241), wherein the light-emitting device emits coherent light having a far-field angle of less than 15 degrees, at a forward current between a laser threshold current and a saturation current therein, and incoherent light at a forward current less than the laser threshold current, wherein the epitaxial structure (20) is arranged on the substrate (50) and further comprises: several first radiation-emitting areas in a first column; and several second radiation-emitting areas in a second column; a conductive layer (60) on the epitaxial structure (20); wherein the contact areas (241) are arranged in a two-dimensional field and are configured to direct a spatially limited current in the light-emitting device to the several first radiation-emitting areas and the several second radiation-emitting areas; and wherein one of the several first contact areas includes a first latitude (w3') and one of the several second contact areas includes a second latitude (w3) that differs from the first latitude (w3'). [2] The light-emitting device according to claim 1, further comprising an electrode (40) on the conductive layer (60), wherein the electrode (40) forms a continuous layer. [3] The light-emitting device according to claim 1 or 2, further comprising several openings (25) formed in the electrode (40) and spaced apart from each other. [4] The light-emitting device according to claim 3, wherein the multiple openings (25) are aligned to the multiple first contact areas and the multiple second contact areas. [5] The light-emitting device according to claim 4, wherein the openings that are oriented towards the multiple first contact areas have a smaller width than the openings that are oriented towards the multiple second contact areas. [6] The light-emitting device according to claim 3, wherein the ratio of the width of the first contact areas to the width of the respective openings (25) is between 0.5 and 1.1.

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