CN218040205U

CN218040205U - Semiconductor laser

Info

Publication number: CN218040205U
Application number: CN202221156819.3U
Authority: CN
Inventors: 李少卿
Original assignee: Xinchen Semiconductor Suzhou Co ltd
Current assignee: Xinchen Semiconductor Suzhou Co ltd
Priority date: 2022-05-13
Filing date: 2022-05-13
Publication date: 2022-12-13
Anticipated expiration: 2032-05-13

Abstract

The application relates to the technical field of semiconductors, and provides a semiconductor laser, and the semiconductor laser includes: a semiconductor substrate; the active region is formed on the semiconductor substrate and forms a multi-mode interference coupler after being etched; a contact layer formed on the multimode interference coupler and on the non-etched portion of the active region; and the two electrode layers are respectively formed on the semiconductor substrate and the contact layer. This application adopts multimode interference coupler as active area, and when the increase active area of very big degree, still has the effect of high-order mode filter, compares in traditional laser structure, has bigger saturated output power, can realize stable single mode output, and has improved semiconductor laser's heat radiation characteristic.

Description

Semiconductor laser

Technical Field

The application belongs to the technical field of semiconductors, and particularly relates to a semiconductor laser.

Background

High power semiconductor lasers have very important applications in optical sensing instruments. In frequency modulated continuous wave optical detection and ranging, a continuously chirped laser signal is used and the distance from the transmitter to the object is obtained by receiving the reflected signal and comparing it with the original signal. Laser radars using frequency modulated continuous wave principles range in applications from autonomous driving of automobiles, where unmanned driving has been written in national strategic planning in many countries, to meteorological and biomedical imaging, where autonomous driving is the developing trend of future automobiles. Lidar is widely studied as a key technology in unmanned driving. The laser phased array radar requires a laser light source to have the characteristic of high power so as to adapt to a complex weather environment. Therefore, the high-power semiconductor laser has important research value and application prospect as an important component in the laser radar.

The waveguide of a semiconductor laser is generally designed as a lateral single mode waveguide for communication purposes, which is low in power and poor in heat dissipation, eventually resulting in low power and poor heat dissipation of the semiconductor laser.

Disclosure of Invention

An object of the embodiments of the present application is to provide a method for manufacturing a semiconductor laser and a semiconductor laser, so as to solve the technical problems of low power and poor heat dissipation of the semiconductor laser in the prior art.

In order to achieve the purpose, the technical scheme adopted by the application is as follows: a method for manufacturing a semiconductor laser is provided, which comprises the following steps:

forming an active region on a semiconductor substrate;

dividing an etching area and a non-etching area above the active area, and etching the active area of the etching area to form a multi-mode interference coupler;

depositing contact layers on the multimode interference coupler and the active area of the etching area;

and respectively forming an electrode layer on the semiconductor substrate and the contact layer.

In one possible design, forming an active region on the semiconductor substrate includes:

sequentially depositing a lower limiting layer, a quantum well layer and an upper limiting layer on the semiconductor substrate;

in the etching process, the upper limiting layer corresponding to the etching region is completely etched, and at least the quantum well layer corresponding to the etching region is over-etched.

In a possible design, in an etching process, the upper limiting layer and the quantum well layer corresponding to the etching region are completely etched, and the lower limiting layer corresponding to the etching region is over-etched.

In one possible design, the epitaxial structure of the active region is a conventional confinement structure or a large optical cavity structure.

In one possible design, the method further includes, before forming the active region on the semiconductor substrate, the steps of:

forming a semiconductor buffer layer on the semiconductor substrate;

the method also comprises the following steps after the active region is formed on the semiconductor substrate:

forming a semiconductor protection layer on the active region;

in the etching process, completely etching the protective layer corresponding to the etching area, and over-etching the active area;

the contact layer is deposited above the semiconductor protection layer and above the semiconductor buffer layer corresponding to the etching area.

In one possible design, the multi-mode interference coupler includes a multi-mode interference coupler waveguide and two first-order mode straight waveguides, the two first-order mode straight waveguides are respectively connected to two opposite sides of the multi-mode interference coupler waveguide, and the width of the multi-mode interference coupler waveguide is larger than the width of the two first-order mode straight waveguides;

wherein two of said multimode interference coupler waveguides are capable of suppressing lasing of a first order mode.

In one possible design, the contact layers on both sides of the multimode interference coupler are proton implanted to form a high resistance region before the electrode layer is formed.

The semiconductor laser manufacturing method has the beneficial effects that: according to the semiconductor laser manufacturing method, after the active region is etched to form the multi-mode interference coupler, the multi-mode interference coupler waveguide width of the multi-mode interference coupler is larger than that of a conventional single-mode waveguide, meanwhile, the multi-mode interference coupler also has the function of a high-order mode filter, the lasing of a first-order mode can be inhibited, and the stable fundamental transverse mode output is finally achieved, so that the luminous power of the semiconductor laser is amplified, and the luminous power of the semiconductor laser is high and the purity is high. In addition, the area of the active region is greatly increased compared with the traditional structure, so that the heat dissipation characteristic of the semiconductor laser is improved, the heat effect of the semiconductor laser is reduced, and the energy consumption is lower.

On the other hand, the present application also provides a semiconductor laser, including:

a semiconductor substrate;

the active region is formed on the semiconductor substrate and forms a multi-mode interference coupler after being etched;

a contact layer formed on the multimode interference coupler and on the non-etched portion of the active region;

and the two electrode layers are respectively formed on the semiconductor substrate and the contact layer.

In one possible design, the active region includes a lower confinement layer, a quantum well layer, and an upper confinement layer sequentially formed on the semiconductor substrate;

the multimode interference coupler comprises at least the upper confinement layer and the quantum well layer.

In one possible design, the multimode interference coupler includes a lower confinement layer, a quantum well layer, and an upper confinement layer.

In one possible design, the semiconductor laser further includes a semiconductor buffer layer formed between the semiconductor substrate and the active region, and a semiconductor protection layer formed on the active region; the multi-mode interference coupler at least comprises the semiconductor protection layer and the active region.

In one possible design, the contact layers on both sides of the multimode interference coupler have high-resistance regions implanted with protons therein.

The application provides a semiconductor laser's beneficial effect lies in: the semiconductor laser provided by the embodiment of the application forms a multimode interference coupler by etching an active region, and has larger active region area because the multimode interference coupler waveguide of the multimode interference coupler has the effect of a high-order mode filter compared with the conventional single-mode waveguide, and simultaneously, the multimode interference coupler also has the effect of a high-order mode filter, so that the lasing of a first-order mode can be inhibited, and finally, the stable fundamental transverse mode output is realized, so that the luminous power of the semiconductor laser has an amplification effect, and the luminous power of the semiconductor laser is high and the purity is high. In addition, the area of the active region is greatly increased compared with the traditional structure, so that the heat dissipation characteristic of the semiconductor laser is improved, the heat effect of the semiconductor laser is reduced, and the energy consumption is lower.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required to be used in the embodiments or the prior art description will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings may be obtained according to these drawings without inventive labor.

Fig. 1 is a schematic flow chart of a method for manufacturing a semiconductor laser according to an embodiment of the present disclosure;

FIG. 2 is a schematic structural diagram of a semiconductor substrate, a semiconductor buffer layer, an active region and a semiconductor protection layer sequentially formed according to an embodiment of the present disclosure;

FIG. 3 is a schematic structural view of the semiconductor buffer layer, the active region and the semiconductor protection layer in FIG. 1 after etching;

FIG. 4 is a schematic view of the structure of FIG. 3 after deposition of a contact layer;

FIG. 5 is a schematic diagram of a method for implanting protons based on the method of FIG. 4;

FIG. 6 is a schematic structural diagram of a two-sided electrode layer formed on the basis of FIG. 4;

FIG. 7 is a schematic top view of an active region forming a multimode interference coupler;

fig. 8 is a schematic structural diagram of the active region in fig. 2;

FIG. 9 is a schematic diagram of a first-order mode after passing through a multimode interference coupler;

fig. 10 is a diagram illustrating a state in which a fundamental transverse mode passes through a multimode interference coupler.

Wherein, in the figures, the various reference numbers:

1. a semiconductor substrate; 2. a semiconductor buffer layer; 3. an active region; 31. a lower confinement layer; 32. a quantum well layer; 33. an upper confinement layer; 4. a semiconductor protective layer; 5. a contact layer; 51. a first contact layer; 52. a second contact layer; 6. a multimode interference coupler; 61. a first order mode straight waveguide; 62. a multi-mode interference coupler waveguide; 7. an N-type electrode; 8. a P-type electrode; 9. a high-resistance region; 10. etching the mask; 11. and (5) masking the photoresist.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.

It will be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship indicated in the drawings for convenience in describing the application and to simplify the description, and are not intended to indicate or imply that the device or element so referred to must have a particular orientation, be constructed in a particular orientation, and be constructed in operation as a limitation of the application.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

Referring to fig. 1 to fig. 7, a method for fabricating a semiconductor laser according to an embodiment of the present disclosure will now be described. The manufacturing method of the semiconductor laser is used for manufacturing the semiconductor laser.

Specifically, the semiconductor laser manufacturing method comprises the following steps:

s10: an active region 3 is formed on a semiconductor substrate 1.

The semiconductor substrate 1 is an N-InP semiconductor substrate, which may be formed by direct deposition, or by depositing InP and then doping the InP to form an N-InP semiconductor substrate, which is not particularly limited herein.

In addition, referring to fig. 8, the forming of the active region 3 on the semiconductor substrate 1 includes the following steps: forming a lower confinement layer 31 on the semiconductor substrate 1; forming a quantum well layer 32 on the lower confinement layer 31; an upper confinement layer 33 is formed on the quantum well layer 32. That is, the active region 3 includes a lower confinement layer 31, a quantum well layer 32, and an upper confinement layer 33.

S30: dividing an etching area and a non-etching area above the active area 3, and etching the active area 3 of the etching area to form a multi-mode interference coupler 6;

specifically, an etching area and a non-etching area are divided above the active area 3, then an etching mask 10 made of a SiO2 material is deposited on the non-etching area of the active area 3, and the position of the active area 3 corresponding to the etching area is etched by etching liquid or etching ions to form the multimode interference coupler 6.

The multimode interference coupler 6 utilizes the self-image effect of the multimode interference coupler waveguide 62, and is a structure in which constructive interference between a plurality of modes excited in the multimode interference coupler waveguide 62 is utilized. Due to the self-image effect, one or more images of the input field will be generated periodically along the propagation direction of the waveguide.

In practical application, after the active region 3 is etched to form the multi-mode interference coupler 6, the width of the multi-mode interference coupler waveguide 62 of the multi-mode interference coupler 6 is larger than that of a conventional single-mode waveguide, so that the area of the active region 3 is larger, and meanwhile, the multi-mode interference coupler 6 also has the function of a high-order mode filter, so that the lasing of a first-order mode can be inhibited, and the stable fundamental transverse mode output is finally realized, so that the light-emitting power of the semiconductor laser is amplified, and the light-emitting power and the purity of the semiconductor laser are high. In addition, the area of the active region 3 is greatly increased compared with the traditional structure, so that the heat dissipation characteristic of the semiconductor laser is improved, the heat effect of the semiconductor laser is reduced, and the energy consumption is lower.

S50: depositing a contact layer 5 on the multimode interference coupler 6 and on the active area 3 of the etching area;

specifically, the contact layer 5 includes a first contact layer 51 and a second contact layer 52, the first contact layer 51 is a P-InP layer, and the second contact layer 52 is a P + -InGaAs layer, that is, an InP layer doped with a P-type material is deposited on the etched regions of the multimode interference coupler 6 and the active region 3, and then an InGaAs layer doped with a P + -type material is deposited on the P-InP layer. The P-InP layer is thicker and wraps the multi-mode interference coupler 6, and the P + -InGaAs layer is directly deposited on the P-InP layer in a planar mode.

S70: electrode layers are formed on the semiconductor substrate 1 and the contact layer 5, respectively.

Specifically, an N-type electrode 7 is formed on the lower side of the semiconductor substrate 1, and a P-type electrode 8 is formed on the upper side of the contact layer 5.

In actual use, currents are respectively led into the N-type electrode 7 and the P-type electrode 8 through an external circuit, the currents flow to the active region 3 and excite light waves in the active region 3, the light waves are amplified and filtered through the multi-mode interference coupler 6 in the active region 3, and finally the fundamental transverse mode with high output power and high purity is output.

S10: forming the active region 3 on the semiconductor substrate 1 includes: a lower confinement layer 31, a quantum well layer 32, and an upper confinement layer 33 are sequentially deposited on the semiconductor substrate 1.

Since the active region 3 includes the lower limiting layer 31, the quantum well layer 32, and the upper limiting layer 33 deposited in sequence from bottom to top, during an etching process, the SiO2 etching mask 10 may be deposited at a position of the upper limiting layer 33 corresponding to the non-etched region, and then the lower limiting layer 31, the quantum well layer 32, and the upper limiting layer 33 are sequentially etched from top to bottom in the etched region, wherein the upper limiting layer 33 corresponding to the etched region needs to be completely etched, and at least the quantum well layer 32 corresponding to the etched region needs to be over-etched, that is, the etching depth at least needs to extend to the lower limiting layer 33 below the quantum well layer 32, so that the formed multimode interference coupler 6 can suppress the lasing of the first-order mode, and thus the fundamental transverse mode output from the multimode interference coupler 6 is output, and further the power of the formed semiconductor laser is higher, the heat dissipation effect is better, and the thickness of the lower limiting layer 31 is not limited.

Preferably, in this embodiment, in the etching process, the upper limiting layer 33 and the quantum well layer 32 corresponding to the etching region need to be completely etched, and the lower limiting layer 31 corresponding to the etching region needs to be over-etched, that is, the entire active region 3 needs to be over-etched, so that the multimode interference coupler 6 can have a better lasing effect of suppressing the first order mode, as shown in fig. 9 and 10, when the active region 3 is over-etched, the first order mode in the active region 3 can be completely suppressed, and a fundamental transverse mode with high purity is output, so that the power of the semiconductor laser is higher.

Further, with the above arrangement, the epitaxial structure of the active region 3 can be a conventional confinement structure or a large optical cavity structure. The conventional confinement structure is a conventional structure of a semiconductor laser, and the large optical cavity structure is formed by thickening the lower confinement layer 31 of the active region 3, so that the thickness of the corresponding active region 3 is larger than that of the active region 3 of the conventional structure. Although the increase of the thickness of the active region 3 may cause the first-order mode lasing, since the over-etching process is performed on the active region 3 in order to form the multi-mode interference coupler 6 in the present application, the filtering capability of the active region 3 for the first-order mode may be improved, and therefore, even if the epitaxial structure of the quantum well layer 32 is set to be a large optical cavity structure, the power of the semiconductor laser may not be affected.

In one embodiment, the following steps are also included before forming the active region 3 on the semiconductor substrate 1: forming a semiconductor buffer layer 2 on a semiconductor substrate 1; the following steps are also included after forming the active region 3 on the semiconductor substrate 1: a semiconductor protection layer 4 is formed on the active region 3.

That is, the semiconductor buffer layer 2, the active region 3, and the semiconductor protection layer 4 are sequentially deposited on the semiconductor substrate 1. Wherein, the semiconductor buffer layer 2 is an N-InP type semiconductor buffer layer 2, and the semiconductor protection layer 4 is an i-InP type semiconductor protection layer 4.

In the etching process, the semiconductor protection layer 4 corresponding to the etching region is completely etched, and the active region 3 corresponding to the etching region is over-etched, that is, at least the semiconductor buffer layer 2 is partially etched, so that the formed multimode interference coupler 6 has a function of inhibiting a first-order mode.

In addition, when the contact layer 5 is formed, the contact layer 5 is deposited on the semiconductor protection layer 4 and on the semiconductor buffer layer 2 corresponding to the etched region.

In this embodiment, the multimode interference coupler 6 is a 1X1 type multimode interference coupler 6, and specifically includes a multimode interference coupler waveguide 62 and two first-order mode straight waveguides 61, where the two first-order mode straight waveguides 61 are respectively and symmetrically connected to two opposite sides of the multimode interference coupler waveguide 62. Assuming that the first direction X in fig. 7 is the length direction of the semiconductor laser and the second direction Y is the width direction of the semiconductor laser, one first-order mode straight waveguide 61, the multimode interference coupler waveguide 62 and the other first-order mode straight waveguide 61 are connected in this order along the first direction X, and the multimode interference coupler 6 is located at a substantially middle position of the semiconductor laser along the second direction Y.

The widths of the two first-order mode straight waveguides 61 are equal, the width of the multi-mode interference coupler waveguide 62 is larger than the widths of the two first-order mode straight waveguides 61, and the two multi-mode interference coupler waveguides 62 can suppress lasing of the first-order mode. The specific widths of the two first-order mode straight waveguides 61 can be calculated according to the light waves excited in the active region 3, and the calculation method is common knowledge in the art and will not be described in detail herein.

In practical applications, light is generally emitted from one side of the semiconductor laser, and therefore, a reflective film is generally disposed outside one of the two first-order mode straight waveguides 61 to prevent light from leaking out, and finally, light is emitted from one of the first-order mode straight waveguides 61.

In one embodiment, proton implantation is performed at the contact layers on both sides of the multimode interference coupler 6 to form a high resistance region before forming the electrode layer. Specifically, the two first-order mode straight waveguides 61 are respectively subjected to proton injection along the contact layers on the two sides in the second direction Y, so as to form the high-resistance regions 9 on the two sides of the first-order mode straight waveguides 61, so that the injected current can be intensively injected into the active region 3 without lateral diffusion, and the light emitting efficiency of the active region 3 is improved.

Referring to fig. 5, during the proton implantation, a photoresist mask 11 may be deposited on the contact layer 5 above the non-etching region, and then the proton implantation may be performed on the contact layer 5 at a position without the photoresist mask 11.

In addition, the injected protons may be He + and H +, or may even be other protons, which is not limited herein.

On the other hand, the application also provides a semiconductor laser which is manufactured by the manufacturing method of the semiconductor laser.

Specifically, the semiconductor laser includes a semiconductor substrate 1, an active region 3, a contact layer 5, and two electrode layers. An active region 3 is formed on a semiconductor substrate 1, a multimode interference coupler 6 is formed on the active region 3 through an etching process, a contact layer 5 is formed on the multimode interference coupler 6 and on a non-etched portion of the active region 3, and two electrode layers are respectively formed on the semiconductor substrate 1 and the contact layer 5. Specifically, an N-type electrode 7 is formed on the lower side of the semiconductor substrate 1, and a P-type electrode 8 is formed on the upper side of the contact layer 5.

It should be noted that the multimode interference coupler 6 is formed by etching on the active region 3 through the etching process in the semiconductor laser manufacturing method.

In one embodiment, referring to fig. 3, the active region 3 includes a lower confinement layer 31, a quantum well layer 32, and an upper confinement layer 33 sequentially formed on the semiconductor substrate 1. The multimode interference coupler 6 at least comprises an upper limiting layer 33 and a quantum well layer 32, that is, when an etching process is performed, the upper limiting layer 31 corresponding to an etching region needs to be completely etched, and at least the quantum well layer 32 corresponding to the etching region needs to be over-etched.

In a preferred embodiment, referring to fig. 3, the multimode interference coupler 6 includes a lower limiting layer 31, a quantum well layer 32 and an upper limiting layer 33, and in the etching process, the upper limiting layer 33 and the quantum well layer 32 corresponding to the etching region need to be completely etched, and the lower limiting layer 31 corresponding to the etching region needs to be over-etched, that is, the whole active region 3 needs to be over-etched.

In one embodiment, referring to fig. 2 and 3, the semiconductor laser further includes a semiconductor buffer layer 2 formed between the semiconductor substrate 1 and the active region 3, and a semiconductor protection layer 4 formed on the active region 3. The multimode interference coupler 6 at least comprises a semiconductor protection layer 4 and an active region 3, and specifically, in the etching process, the semiconductor protection layer 4 corresponding to the etching region is completely etched, and the active region 3 corresponding to the etching region is over-etched, that is, at least part of the semiconductor buffer layer 2 is etched, so that the formed multimode interference coupler 6 has a function of inhibiting a first-order mode.

The contact layer 5 is deposited on the semiconductor protection layer 4 and on the semiconductor buffer layer 2 corresponding to the etched region.

In one embodiment, referring to fig. 5, the contact layer 5 on both sides of the multimode interference coupler 6 has high resistance regions 9 implanted with protons. Specifically, the two first-order mode straight waveguides 61 are respectively subjected to proton injection along the contact layers on the two sides in the second direction Y, so as to form the high-resistance regions 9 on the two sides of the first-order mode straight waveguides 61, so that the injected current can be intensively injected into the active region 3 without lateral diffusion, and the light emitting efficiency of the active region 3 is improved.

The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A semiconductor laser, comprising:

a semiconductor substrate;

2. The semiconductor laser of claim 1, wherein the active region comprises a lower confinement layer, a quantum well layer, and an upper confinement layer sequentially formed on the semiconductor substrate;

the multimode interference coupler includes at least the upper confinement layer and the quantum well layer.

3. The semiconductor laser of claim 2, wherein the multimode interference coupler comprises a lower confinement layer, a quantum well layer, and an upper confinement layer.

4. The semiconductor laser of claim 1, wherein the epitaxial structure of the active region is a large optical cavity structure.

5. The semiconductor laser according to any one of claims 1 to 4, further comprising a semiconductor buffer layer formed between the semiconductor substrate and the active region, and a semiconductor protective layer formed on the active region; the multi-mode interference coupler at least comprises the semiconductor protection layer and the active region.

6. A semiconductor laser as claimed in any one of claims 1 to 4 wherein the multi-mode interference coupler comprises a multi-mode interference coupler waveguide and two first order mode straight waveguides connected to opposite sides of the multi-mode interference coupler waveguide, respectively, the width of the multi-mode interference coupler waveguide being greater than the width of the two first order mode straight waveguides;