TWI731473B - Laser device - Google Patents

Abstract

The laser device as disclosed includes an epitaxial structure, at least a first and a second emitters which are arranged next to each other, and a plurality of trenches arranged between the emitters in the epitaxial structure. From a top view of the laser device, it shows that there is only one trench located between the first emitter and the second emitter, and the line passing the center of the first emitter and the center of the second emitter also passes the trench located therebetween.

Description

Laser components

The present disclosure relates to a laser element, in particular to a vertical cavity surface emitting laser (VCSEL).

In view of the popularity of facial recognition functions in consumer electronic products and the increasing trend of laser components in 3D sensing applications, the use of semiconductor lasers as light sources is bound to explode.

In the field of 3D sensing applications, the use of Vertical Cavity Surface Emitting Laser (VCSEL) as the light source will face the limitation of light conversion efficiency, the size of the device must be reduced, and the need to further improve the adjustment of the device. Challenges such as variable frequency bandwidth.

In view of the foregoing, the present disclosure proposes a vertical cavity surface emitting laser (VCSEL) design, which uses the same plane metal electrode to generate a large current drive and reduces its series resistance (Rs) to reduce thermal interference. , Thereby improving the light conversion efficiency of the VCSEL. At the same time, the present disclosure utilizes the shared design of the wet oxide trenches in the VCSEL to reduce the spacing of the light-emitting holes, thereby reducing the size of the laser element. In addition, using the ohmic contact in the VCSEL The shape design can produce a metal shield to reduce the number of high-ordered modes (High-ordered Mode), simplify its optical frequency spectrum, and increase the frequency modulation bandwidth.

The present disclosure provides a laser device, which includes an epitaxial structure, at least one first light-emitting hole and a second light-emitting hole adjacent to each other, and a plurality of recessed structures formed in the epitaxial structure and Located between adjacent light-emitting holes. From the top view of the laser element, only one of the plurality of recess structures is located between the first light-emitting hole and the second light-emitting hole, and the center of the first light-emitting hole and the second light-emitting hole are connected The line passes through the recess structure.

100: Laser component

110: substrate

120: epitaxial structure

122: The first semiconductor structure

124: active structure

125, 1251, 1252, 1253: current limiting layer

125A, 125A ₁ , 125A ₂ , 125A ₃ : opening/lighting hole

126: Second semiconductor structure

130: contact layer

130’: Ring

130A: Ring part opening

130P: Extension

140, 140A, 140B, 140C, 140D, 140E: recess structure

140L ₁ , 140L ₂ : Long side

140S ₁ , 140S ₂ : short side

150: protective layer

150A: protective layer opening

160: Electrode structure

200: Laser component

I: blocking structure

O, O ₁ , O ₂ , O ₃ : the center of the opening/the center of the light-emitting hole

H ₁ , H ₂ : depth

D12, D23: distance

In order to further understand the features and technical content of the present disclosure, please refer to the following detailed description of the embodiments of the present disclosure and the accompanying drawings. However, the detailed description of the features and the accompanying drawings are provided for reference and illustration, and are not intended to limit the present invention; among them: Figure 1 is a top view of a laser element according to an embodiment of the present disclosure; Figures 2A and 2B are schematic cross-sectional views, respectively illustrating the cross-sectional structure of the laser element shown from the line A-A' and line B-B' in Figure 1; Figure 2C is a schematic top view, which Schematically illustrate the contact layer in the laser device according to an embodiment of the present disclosure; FIG. 3 is a schematic top view of the laser device according to an embodiment of the present disclosure; FIG. 4A and FIG. 4B illustrate from FIG. 3 The schematic diagram of the cross-sectional structure of the laser element shown on the line A-A' and the line B-B'; and

The following describes the concept of the present disclosure with reference to the drawings and exemplary embodiments. In the drawings or descriptions, similar or identical parts use the same symbols; in addition, the drawings are for the benefit of Drawing for understanding, the thickness and shape of each layer in the drawing are not the actual size or proportional relationship of the element, unless otherwise specified. It should be noted that the elements not shown in the drawings or described in the specification can be in the form known to those who are familiar with the art of the present disclosure.

FIG. 1 is a schematic top view of a laser device 100 according to an exemplary embodiment of the present disclosure. Fig. 2A and Fig. 2B respectively illustrate the cross-sectional structure of the laser element 100 shown by the line A-A' (passing through the recess structure) and the line B-B' (not passing through the recess structure) in Figure 1, respectively. For the sake of clarity, the protective layer and electrode structure covering the contact layer 130 are not shown in Figure 1 (ie, the protective layer 150 and the electrode structure 160 in the cross-sectional structure shown in Figures 2A and 2B) .

As shown in FIG. 1 and FIGS. 2A to 2B, the laser device 100 includes a substrate 110, an epitaxial structure 120, a contact layer 130 on the epitaxial structure 120, and light-emitting holes. The epitaxial structure 120 includes a first semiconductor structure 122, an active structure 124 and a second semiconductor structure 126. The laser element 100 further includes a current confinement layer 125 located between the contact layer 130 and the substrate 110. In detail, the current confinement layer 125 may be located between the active structure 124 and the second semiconductor structure 126 or between the active structure 124 and the first semiconductor structure 122. The current limiting layer 125 has an opening 125A for allowing current to flow through and generating light. The opening 125A is defined as a light-emitting hole. The center O of the opening 125A corresponds to the center position of the entire laser element 100 (also O)

The laser device 100 further includes a plurality of recess structures 140 formed in the epitaxial structure 120, that is, the recess structure 140 is formed in the first semiconductor structure 122, the active structure 124 and the second semiconductor structure 126. In detail, the recess structure 140 penetrates the first semiconductor structure 122, the active structure 124 and a part of the second semiconductor structure 126 to expose the second semiconductor structure 126. Alternatively, the recess structure 140 penetrates the first semiconductor structure 122, the active structure 124, and the second semiconductor structure 126 to expose the substrate 110. In this embodiment, the recess structure 140 is used for a subsequent oxidation process to form the current limiting layer 125. In this embodiment, as viewed from the top view, the laser element 100 has six recess structures 140 and the opening 125A is generally circular. Each recess structure 140 has an arc-shaped boundary, and the arc-shaped boundary is formed by two relatively long sides 140L ₁ , 140L ₂ and two relatively short sides 140S ₁ , 140S ₂ . The two opposite long sides 140L ₁ and 140L ₂ of the arc-shaped boundary are arcs with a central angle of 30°. Through the oxidation process or/and the control of the shape of the recess structure 140, the size and shape of the opening 125A can be defined, that is, the size and shape of the light-emitting hole of the laser device 100 (which will be further described later).

The contact layer 130 includes a ring portion 130', a plurality of extension portions 130P extending inward from the ring portion 130' (toward the center of the light-emitting hole), and a ring portion opening 130A. The center of the ring opening 130A corresponds to the opening 125A. The plurality of extension parts 130P are not connected to each other. The number of extensions 130P corresponds to the number of recess structures 140. For example, in this embodiment, the number of the extension portion 130P and the recess structure 140 is six. In other embodiments, the number of the extension portion 130P and the recess structure 140 may be 2, 4, 8, 12, or 14. As shown in FIG. 1, the plurality of extension portions 130P are aligned with the recess structure 140, that is, one extension portion 130P corresponds to one recess structure 140.

In this embodiment, the length d of each extension portion 130P of the contact layer 130 protruding inward from the annular portion 130 thereof is 1 to 3 microns. The ratio of the total area of all the extending portions 130P protruding inwardly of the annular portion 130' to the area of the inner circle of the annular portion 130' (that is, the area of the dashed circle in Figure 2C) is between 6% and 36%. The design of the extension 130P can avoid the tip discharge effect, provide a metal shielding effect, and help reduce the number of high-ordered modes of the laser element 100.

The laser element 100 further includes a protective layer 150, an electrode structure 160, and a back electrode 170. The protective layer 150 covers the contact layer 130 and covers the bottom surface and the side surface of the recess structure 140. The electrode structure 160 is located on the protective layer 150 and filled in the recess structure 140 for the overall electrical connection of the laser element 100 to the outside. The electrode structure 160 may be partially filled without filling the recess structure 140 or completely filling the recess structure 140. Back electrode 170 covers the substrate 110 and is used for the overall electrical connection of the laser element 100 to the outside. The electrode structure 160 and the back electrode 170 include metal.

As shown in FIGS. 1 and 2B, the protective layer 150 has a plurality of protective layer openings 150A. The extension 130P (or the recess structure 140) is misaligned with the protective layer opening 150A, that is, each extension 130P1 (or each recess structure 140) does not correspond to each protective layer opening 150A.

The laser element 100 further optionally includes a blocking structure I formed in the epitaxial structure 120 to block the transmission of lateral current to reduce the overall series resistance of the laser element, further reduce the RC constant of the laser element, and effectively improve the modulation The bandwidth (that is, the operating bandwidth). The barrier structure I can be formed through an oxidation process or an ion implant process. As shown in FIGS. 2A and 2B, the blocking structure I is formed in the second semiconductor structure 126. In other embodiments, the blocking structure I may be further formed in the first semiconductor structure 122 or/and the active structure 124.

In this embodiment, the first semiconductor structure 122 and the second semiconductor structure 126 respectively comprise a plurality of layers of different refractive index stacked alternately and periodically (for example, the interaction of the AlGaAs layer with high aluminum content and the AlGaAs layer with low aluminum content). Periodically stacked) to form a Distributed Bragg Reflector (DBR), so that the light emitted from the active structure 124 can be reflected in the two mirrors to form co-dimmer. The reflectivity of the first semiconductor structure 122 is higher than the reflectivity of the second semiconductor structure 126, so that the co-dimming light is emitted toward the direction of the electrode structure 160. The materials of the first semiconductor structure 122, the second semiconductor structure 126 and the active structure 124 include Group III and V compound semiconductors, such as GaAs, InGaAs, AlGaAs, AlGaInAs, GaP, InGaP, AlInP, AlGaInP, GaN, InGaN, AlGaN, AlGaInN, AlAsSb , InGaAsP, InGaAsN or AlGaAsP and other compounds. In the embodiments of the present disclosure, unless otherwise specified, the above chemical expressions include "compounds that meet the chemical dose" and "compounds that do not meet the chemical dose", where the "compounds that meet the chemical dose" are, for example, Group III elements The total element dose of is the same as the total element dose of Group V elements; on the contrary, the "non-chemical dose compound" is, for example, the total element dose of Group III elements and the total element dose of Group V elements are different. For example, the chemical formula is AlGaInAs, which means that it contains three-group elements aluminum (Al) and/or gallium (Ga) and/or indium (In), and contains five-group elements arsenic (As), of which group three elements (aluminum) And/or the total element dose of gallium and/or indium) may be the same as or different from the total element dose of the group V element (arsenic). In addition, if each compound represented by the above chemical formula is a compound that meets the stoichiometric dose, AlGaAs stands for Al _x1 Ga _(1-x1) As, where 0<x1<1; AlInP stands for Al _x2 In _(1-x2) P, where 0<x2<1; AlGaInP stands for (Al _y1 Ga _(1-y1 ) _1-x3 In _x3 P, where 0<x3<1, 0<y1<1; AlGaInAs stands for (Al _y2 Ga _{(1 -y2)} ) _1-x4 In _x4 As, where 0≦x4≦1, 0≦y2≦1; AlGaN stands for Al _x5 Ga _(1-x5) N, where 0<x5<1; AlAsSb stands for AlAs _x6 Sb _(1-x6) , where 0≦x6≦1; InGaP stands for In _x7 Ga _(1-x7) P, where 0<x7<1; InGaAsP stands for In _x8 Ga _1-x8 As _1-y3 P _y3 , where , 0≦x8≦1, 0≦y3≦1; InGaAsN stands for In _x8 Ga _1-x8 As _1-y4 N _y4 , where 0<x9<1, 0<y4<1; AlGaAsP stands for Al _x10 Ga _1-x10 As _1-y5 P _y5 , where 0<x10<1, 0<y5<1 InGaAs represents In _x11 Ga _(1-x11) As, where 0<x11<1; InGaN represents In _x12 Ga _(1-x12) N , Where 0<x12<1; AlGaInN stands for (Al _y6 Ga _(1-y6 ) _1-x13 In _x13 P, where 0<x13<1, 0<y6<1.

Depending on the material, the active structure 124 can emit infrared light with a peak wavelength between 700nm and 1700nm, red light with a peak wavelength between 610nm and 700nm, and yellow light with a peak wavelength between 530nm and 570nm. , Green light with a peak wavelength between 490nm and 550nm, blue or deep blue light with a peak wavelength between 400nm and 490nm, or ultraviolet light with a peak wavelength between 250nm and 400nm. In this embodiment, the peak wavelength of the active structure 204 is infrared light between 750 nm and 1200 nm.

As described above, when the first semiconductor structure 122 and the second semiconductor structure 126 include a plurality of film layers and both include aluminum, the aluminum in one or more layers of the first semiconductor structure 202 can be contained The amount is greater than 97% (defined as the current limiting layer 125) and greater than the aluminum content of the active structure 124, the other film layers of the first semiconductor structure 122, and the second semiconductor structure 126, so that after the oxidation process, the aluminum content is greater than 97% of the layer or parts of these layers will be oxidized to form a current limiting layer (for example, aluminum oxide), and the unoxidized part will be an opening. In detail, when the recess structure 140 is formed in the first semiconductor structure 122, the active structure 124, and the second semiconductor structure 126, the sidewalls of the first semiconductor structure 122, the active structure 124, and the second semiconductor structure 126 are exposed, so When the laser device 100 is placed in an oxygen-containing environment, the oxygen gas will pass through the recess structure 140 and the first semiconductor structure 122, the active structure 124 or the second semiconductor structure 126 to chemically react to form the current limiting layer 125. Therefore, the depth H1 and shape (aluminum oxide depth) of the current limiting layer 125 can be adjusted to define the shape of the opening 125A by controlling the position and number of the recess structures 140 and the oxidation process (such as oxygen concentration or/and oxidation time). . In this embodiment, as viewed from the top view, the current limiting layer 125 is generally annular, and the opening 125A is generally circular.

Similarly, the materials of the first semiconductor structure 122, the second semiconductor structure 126, and the active structure 124 can be designed, and a wet oxidation process can be performed to form the barrier structure I therein. As shown in FIGS. 2A and 2B, the blocking structure I has a depth H2 smaller than a depth H1 of the current confinement layer 125. The depth H1 is 6-12um and the depth H2 is 2um-5um. Alternatively, hydrogen ions (H ⁺ ), helium ions (He ⁺ ), or argon ions (Ar ⁺ ) are implanted to perform the ion implantation process to form the barrier structure I. In one embodiment, when the current confinement layer 125 is formed by an ion implantation process, the laser device 100 may not have the recess structure 140.

The contact layer 130 is an ohmic contact layer and forms an electrical connection with the epitaxial structure 120, and its material may include metal, metal alloy, metal oxide or semiconductor. Metals include aluminum (Al), silver (Ag), chromium (Cr), platinum (Pt), nickel (Ni), germanium (Ge), beryllium (Be), gold (Au), titanium (Ti), tungsten (W) ) Or zinc (Zn). Metal alloys include alloys of the aforementioned metals. Metal oxide (transparent conductive oxygen Transparent Conductive Oxide, TCO) includes indium tin oxide (ITO), indium oxide (InO), tin oxide (SnO), cadmium tin oxide (CTO), antimony tin oxide (ATO), aluminum zinc oxide (AZO), oxide Zinc tin (ZTO), gallium zinc oxide (GZO), indium tungsten oxide (IWO), zinc oxide (ZnO), or indium zinc oxide (IZO). The semiconductor includes AlGaAs, GaAs, or InGaP.

FIG. 3 is a schematic top view of a laser element 200 according to an embodiment of the disclosure. Fig. 4A and Fig. 4B are respectively the cross-sectional structure of the laser element 200 shown by the line A-A' and the line B-B' in Fig. 3. Figure 3, Figure 4A to Figure 4B, Figure 1, Figure 2A to Figure 2B use the same symbols to describe the same elements, and the materials and characteristics of these elements are as described above, so they will not be repeated. For clarity of the drawing, the protective layer and electrode structure covering the contact layer 130 (that is, the protective layer 150 and the electrode structure in the cross-sectional structure shown in Figures 4A and 4B are not shown in the schematic top view of Figure 3). Electrode structure 160).

As shown in FIG. 3, the laser element 200 includes a plurality of light-emitting holes, and the light-emitting holes are the openings 125A of the current confinement layer 125 in the laser element 200. The light-emitting holes are arranged in an array. In a top view, the plurality of openings 125A (light-emitting holes) in the laser element 200 are arranged in the most densely packed manner. In this embodiment, the plurality of openings are arranged in a hexagonal most densely packed manner, that is, six adjacent openings are formed around each opening. Furthermore, six recess structures 140 surround one opening and each recess structure 140 is located between two adjacent openings. In one embodiment, more than two (for example: three, four or five) adjacent openings are formed around each opening. In other words, more than two (for example: three, four, or five) recess structures 140 surround one opening and each recess structure 140 is located between two adjacent openings.

As described above, the recess structure 140 is used for the oxidation process. During the oxidation process, oxygen reacts chemically in all directions. Therefore, in the laser element 200, through the recess structure 140, current can be formed to both sides (two opposite long sides 140L2, as shown in Figure 1) at the same time. The confined layer defines the openings. In other words, each opening 125A shares a recess structure with adjacent openings 125A. 140. In detail, as shown in FIG. 4A, taking two adjacent openings 125A1 and 125A2 as an example, the current confinement layer 1252 is formed through the recess structure 140A; the current confinement layer 1251 is formed through the recess structure 140B; and the current confinement layer 1251 is formed through the recess structure 140C To form a current confinement layer 1253. The current confinement layers 1252, 1251 define the opening 125A1; the current confinement layers 1252, 1253 define the opening 125A2. It can be seen from the above that two openings (light-emitting holes) can be defined only through three concave structures (not surrounding the same opening), that is, two adjacent openings share the concave structure 140 therebetween or two adjacent openings. There is only one recess structure 140 between the openings. From a cross-sectional view, the laser device 200 has N recess structures and N-1 openings (light-emitting holes), and N is a positive integer. In one embodiment, N is a positive integer greater than 2. In other embodiments, N is not particularly limited. It can be, for example, greater than 3, 4, 5, 6, 7,..., depending on the specifications of the laser element 200 (ie, the required number of light-emitting holes) And choose.

As mentioned above, the shape of each opening 125 is defined by the oxidation process of the six surrounding recessed structures 140. The above is only a cross-sectional view for a brief description, which does not mean that one recessed structure 140 can define an opening. . Therefore, referring to Figure 3, the six recess structures 140 can jointly define an opening 125A and further define six adjacent openings at the same time. In detail, each of the six recess structures 140 can simultaneously align both sides ( The two opposite long sides 140L2 (as shown in Figure 1) form a current confinement layer and define openings on both sides. In other words, all the six recess structures 140 surrounding an opening 125A can share the recess structure 140 therebetween with adjacent openings, so that the distance between adjacent openings can be further reduced. In other embodiments, depending on actual applications, among the six recess structures 140 surrounding an opening 125A, only two, three, four, or five of the six recess structures 140 are shared with adjacent openings.

As shown in Figure 3, the plurality of openings 125A (light-emitting holes) in the laser element 200 are arranged in a hexagonal most densely packed manner, so that there are three adjacent light-emitting holes 125A ₁ , 125A ₂ , and 125A _{3 of the laser element.} the first emission hole center O 125A _{1 1} and the distance between _the second emission hole center O 125A ₂ D12 is equal to the center of the second light emitting aperture 125A ₂ O ₂ and the center of the third light emitting aperture 125A ₃ O ₃ The distance D23. In the present embodiment, the first holes 125A ₁ and the light emission center of the second light emitting aperture 125A ₂ O ₁ -O ₂ connection through the recess structure 140B, 125A ₂ and the third light emitting aperture of the second aperture line of centers of 125A ₃ O ₂ -O ₃ through the recess structure 140D, and the third light emitting aperture 125A ₃ and the center of the first light emitting connection hole 125A ₁ O ₃ -O ₁ structure through the recess 140E.

In this embodiment, the contact layer 130 is formed to have a plurality of ring portions 130' separated from each other, and the center of the ring portion opening 130A of each ring portion 130' corresponds to each corresponding opening 125A. As seen from the cross-sectional view, adjacent annular portions 130' are separated by a recess structure 140.

In addition, optionally, the laser element 200 may include a plurality of blocking structures I separated from each other and discontinuous to block the transmission of the lateral current. The blocking structure I is formed between adjacent openings 125A (or recess structures 140). In other words, a plurality of openings 125A (or recess structures 140) surround a blocking structure I. In this embodiment, a blocking structure I is surrounded by three openings 125A (or recess structures 140) adjacent to each other. Furthermore, there is a recess structure 140 between any two blocking structures I.

The laser element of the present disclosure is a Vertical Cavity Surface Emitting Laser (VCSEL), especially a VCSEL with closely arranged light-emitting holes. In the present disclosure, by sharing the concave structure required to implement the wet oxidation process in the laser element, the distance between adjacent openings (light-emitting holes) can be further reduced, thereby improving the identification efficiency of the laser element and reducing Packaging cost.

According to the present disclosure, each light-emitting hole of the laser element is formed with six concave structures uniformly distributed (that is, arranged at a distance of 60 degrees). By implementing the wet oxidation process through the six concave structures, the The epitaxial structure of the laser element forms an approximately circular opening (that is, the light-emitting hole of the laser element). According to this disclosure, each recess structure is shared by two adjacent light-emitting holes, so that The plurality of light-emitting holes in the laser element of the present disclosure are arranged in the most densely packed manner, which increases the layout space of the light-emitting hole structure in the laser element.

In the present disclosure, a blocking structure is formed on the current injection path between adjacent light-emitting hole structures, which can block the lateral current between the two light-emitting hole structures to reduce the series resistance (Rs), thereby Lowering the RC constant of the laser component effectively increases the modulation bandwidth (that is, the operating bandwidth). Furthermore, the electrode structures of the present disclosure are generally formed on the same plane, thereby shortening the current path, reducing the series resistance, and helping to reduce the thermal interference of the laser element and improve the light conversion efficiency of the laser element. In one embodiment, when the laser element is operated at a high current (above 0.5A), the above-mentioned effect is particularly significant.

In this disclosure, the contact layer of the laser element has a ring-shaped structure and has an inwardly extending extension, which can avoid the tip discharge effect of the current and produce a metal shielding effect, thereby reducing the number of high-order modes to make the light spectrum simplify. In this way, because the laser element of the present disclosure has a relatively simple optical mode of the spectrum, the photodetector can generate a better light response during application, thereby improving the identification efficiency.

In summary, the present disclosure provides a laser element with excellent photoelectric characteristics, which has high light conversion efficiency, small size, effectively improved operating bandwidth and recognition rate, and has a deep potential for 3D sensing applications.

It should be noted that the aforementioned embodiments mentioned in the present disclosure are only used to illustrate the present disclosure, and not to limit the scope of the present disclosure. The various modifications and changes made to this disclosure by those who are familiar with the field and skills of this disclosure do not deviate from the spirit and scope of this disclosure. The same or similar components in different embodiments, or components denoted by the same symbol in different embodiments, have the same physical or chemical characteristics. In addition, under appropriate circumstances, the above-mentioned embodiments of the present disclosure can be combined or replaced with each other, and are not limited to the specific embodiments described above. The connection relationship between the specific component and other components described in one embodiment can also be applied to other embodiments, and it falls within the scope of the patent application attached to this disclosure.

100: Laser component

125A: current limiting layer

130: metal contact layer

130’: Ring

130A: Ring part opening

130P: Extension

140: Recessed structure

140L ₁ , 140L ₂ : Long side

140S ₁ , 140S ₂ : short side

150A: protective layer opening

I: blocking structure

Claims (10)

A laser element includes: an epitaxial structure; a plurality of light-emitting holes adjacent to each other and at least a first light-emitting hole and a second light-emitting hole; and a plurality of recessed structures, each formed in the epitaxial structure and Is located between the plurality of light-emitting holes; wherein, from the top view of the laser element, only one of the plurality of recessed structures is located between the first light-emitting hole and the second light-emitting hole, and the first The central line of the light-emitting hole and the second light-emitting hole passes through the concave structure. The laser element described in item 1 of the scope of patent application, wherein, as viewed from a cross-sectional view of the laser element, the laser element has N recess structures and N-1 light-emitting holes, and N is greater than 2 Positive integer. The laser device described in item 1 of the scope of patent application further includes a contact layer. The contact layer includes a ring portion and a plurality of extension portions extending inward from the ring portion. A laser element includes: a substrate; an epitaxial structure located on the substrate; a current confinement layer having an opening; a contact layer located on the epitaxial structure and having an annular portion and a direction from the annular portion A plurality of extensions extending inside; an electrode structure located on the contact layer; and a protective layer located between the contact layer and the electrode structure. The laser element described in item 4 of the scope of the patent application further includes a plurality of concave structures, and the contact layer is located between two of the plurality of concave structures. The laser element described in item 3 or item 5 of the scope of patent application, wherein, as viewed from the top view of the laser element, each of the plurality of extensions is in the same structure as the plurality of recesses The structure of each recess is aligned. The laser element described in item 4 of the scope of patent application further includes a plurality of protective layer openings located above the contact layer, wherein, as viewed from the top view of the laser element, each of the plurality of extensions The extension part is misaligned with each of the plurality of protective layer openings. For the laser element described in item 1 or item 5 of the scope of patent application, the electrode structure is filled in the plurality of concave structure. According to the laser device described in item 4 of the scope of patent application, the electrode structure and the contact layer have different shapes. According to the laser device described in claim 4, the contact layer has a side wall, and the protective layer covers the side wall.

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