Active layer structure and surface emitting resonator

Abstract

The application provides an active layer structure and a surface-emitting resonant cavity laser, and the active layer structure comprises, from bottom to top, an N-doped layer, a first confinement layer, a multiple quantum well layer, a second confinement layer and a P-doped layer; wherein the multiple quantum well layer comprises barrier layers and well layers arranged alternately; the number of the barrier layers is equal to the number of the well layers plus one; and the energy band values corresponding to each layer in the active layer structure are distributed in a non-symmetrical mode as a whole. By arranging the active layer multi-layer structure with the energy band values distributed in a non-symmetrical mode as a whole, the application can effectively prevent electrons from crossing the barrier layers in the active region to reach the confinement layer on the P-doped side, prevent abnormal service life caused by high temperature or high current operation of the component, improve the service life of the device, and promote most carriers to stay in the well layer, increase the carrier recombination probability, and further improve the internal quantum efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to an active layer structure and a surface-emitting resonant cavity laser. BACKGROUND

[0002] In a conventional VCSEL semiconductor laser, well layers, barrier layers, confinement layers and doped layers of an active layer are made of different energy gap materials, and are grown by metal organic chemical vapor deposition (MOCVD). When the conventional epitaxial active layer structure has an active region as the center, it often has a symmetrical structure, which causes electrons to easily cross the barrier layer in the active region to reach the confinement layer on the P-type doped side, resulting in abnormal service life of the component at high temperature or high current. SUMMARY

[0003] The present application aims to provide an active layer structure and a surface-emitting resonant cavity laser. By arranging the active layer multi-layer structure with an overall asymmetric distribution of energy band values, the electrons can be effectively prevented from crossing the barrier layer in the active region to reach the confinement layer on the P-type doped side, preventing abnormal service life of the component at high temperature or high current, and improving the service life of the device. Most of the carriers are left in the well layer, increasing the carrier recombination probability, and thus improving the internal quantum efficiency.

[0004] In a first aspect, an embodiment of the present application provides an active layer structure, which comprises: an N-type doped layer, a first confinement layer, a composite quantum well layer, a second confinement layer and a P-type doped layer arranged in sequence from bottom to top; wherein the composite quantum well layer comprises barrier layers and well layers arranged alternately; the number of the barrier layers is one more than the number of the well layers; and the energy band values of each layer in the active layer structure correspond to an overall asymmetric distribution.

[0005] In a preferred embodiment of the present application, the number of well layers in the composite quantum well layer is odd.

[0006] In a preferred embodiment of the present application, the composite quantum well layer comprises: a first barrier layer, a first well layer, a second barrier layer, a second well layer, a third barrier layer, a third well layer and a fourth barrier layer arranged in sequence from bottom to top; wherein the energy band value of the second barrier layer is higher than that of the other barrier layers; and in a preferred embodiment of the present application, the energy band value of the first confinement layer is higher than that of the second confinement layer.

[0007] In a preferred embodiment of the present application, the N-type doped layer comprises: a first N-doped layer, a second N-doped layer and a third N-doped layer arranged in sequence from bottom to top; the energy band value of the third N-doped layer is smaller than that of the first N-doped layer and larger than that of the second N-doped layer.

[0008] In the preferred embodiment of the present application, the P-type doped layer comprises a first P-doped layer and a second P-doped layer arranged in sequence from bottom to top; the energy band value corresponding to the second P-doped layer is greater than the energy band value corresponding to the first P-doped layer.

[0009] In the preferred embodiment of the present application, the energy band values of the first N-doped layer, the second energy barrier layer, the second confinement layer and the second P-doped layer are the same; the energy band values of the third N-doped layer, the first energy barrier layer, the third energy barrier layer and the fourth energy barrier layer are the same.

[0010] In the preferred embodiment of the present application, the materials corresponding to the first N-doped layer, the second N-doped layer and the third N-doped layer are respectively Al (0.9) Ga (0.1) As, Al (0.1) Ga (0.9) As and Al (0.3) Ga (0.7) As.

[0011] In the preferred embodiment of the present application, the materials corresponding to the first P-doped layer and the second P-doped layer are respectively Al (0.7) Ga (0.3) As and Al (0.9) Ga (0.1) As.

[0012] In the second aspect, the embodiments of the present application further provide a surface-emitting resonant cavity laser, which comprises a substrate, a buffer layer, an N-type Bragg reflection layer, an active layer structure as described in the above aspect, an oxidation layer and a P-type Bragg reflection layer arranged in sequence from bottom to top.

[0013] The active layer structure and the surface-emitting resonant cavity laser provided by the embodiments of the present application have the following beneficial effects: the active layer structure comprises an N-type doped layer, a first confinement layer, a multiple quantum well layer, a second confinement layer and a P-type doped layer arranged in sequence from bottom to top; the multiple quantum well layer comprises energy barrier layers and well layers arranged alternately; the number of the energy barrier layers is equal to the number of the well layers plus one; and the energy band values corresponding to the layers in the active layer structure are distributed in an overall asymmetric mode. By arranging the active layer multi-layer structure with the energy band values distributed in an overall asymmetric mode, the electrons can be effectively prevented from passing through the energy barrier layers in the active region to reach the confinement layer on the P-type doped side, so as to prevent the abnormal service life caused by high temperature or high current operation of the component and improve the service life of the device; and most of the carriers are kept in the well layers, so as to increase the carrier recombination probability and further improve the internal quantum efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the description of the specific embodiments or the prior art. Obviously, the drawings described below are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0015] Figure 1 A band diagram of an active layer structure in the prior art;

[0016] Figure 2 An electron-hole recombination diagram in an active layer structure in the prior art;

[0017] Figure 3 A schematic diagram of an active layer structure provided by an embodiment of the present application;

[0018] Figure 4 A band diagram of an active layer structure provided by an embodiment of the present application;

[0019] Figure 5 An electron-hole recombination diagram in an active layer structure provided by an embodiment of the present application;

[0020] Figure 6 A schematic diagram of another active layer structure provided by an embodiment of the present application;

[0021] Figure 7 A band diagram of another active layer structure provided by an embodiment of the present application;

[0022] Figure 8 A contrast simulation diagram of an electric field intensity provided by an embodiment of the present application;

[0023] Figure 9 A structural schematic diagram of a surface-emitting resonant cavity laser provided by an embodiment of the present application. DETAILED DESCRIPTION

[0024] The technical solutions of the present application will be described clearly and completely below in conjunction with embodiments. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0025] In the prior art, the traditional epitaxial active layer structure is often in a symmetrical structure form with the active region as the center, as shown in FIG. 1, wherein the band values of the plurality of confinement layers, barrier layers and well layers in the active layer structure are distributed in a center-symmetrical manner. This can cause the electrons to easily cross the barrier layers in the active region and reach the confinement layers on the P-type doped side, as shown in FIG. 2. Figure 1 The present application provides an active layer structure, which can effectively prevent the electrons from crossing the barrier layers in the active region and reaching the confinement layers on the P-type doped side.Figure 2 As shown in the figure, abnormal service life is caused when the component is at high temperature or high current.

[0026] Based on this, the embodiment of the present application provides an active layer structure and a face emitting resonant cavity laser. By setting the active layer multi-layer structure with the energy band value in the overall asymmetric distribution, the electrons can be effectively prevented from crossing the energy barrier layer in the active region to reach the confinement layer on the P-type doped side, the abnormal service life caused by high temperature or high current operation of the component is prevented, the device service life is improved; and most of the carriers are left in the well layer, the carrier recombination probability is increased, and the internal quantum efficiency is improved.

[0027] In order to facilitate the understanding of the embodiment, first, an active layer structure disclosed by the embodiment of the present application is introduced in detail.

[0028] Figure 3 An active layer structure provided by the embodiment of the present application, the active layer structure comprises: N-type doped layer 11, first confinement layer 12, composite quantum well layer 13, second confinement layer 14 and P-type doped layer 15 arranged in sequence from bottom to top; wherein the composite quantum well layer 13 comprises energy barrier layer 131 and well layer 132 arranged alternately; the number of energy barrier layers 131 is equal to the number of well layers 132 plus one; Figure 3 The energy band value corresponding to each layer in the active layer structure is overall in an asymmetric distribution, as shown in the figure. Figure 4

[0029] The main purpose of the well layer 132 is to make the electrons and holes meet in the well layer and then recombine to become photons; the main purpose of the energy barrier layer 131 is to prevent the carriers from easily crossing the energy barrier layer, but to cross the energy barrier layer after the well layer is filled; the main purpose of the confinement layer (the first confinement layer 12 and the second confinement layer 14) is to block too many carriers from continuously crossing the well layer and the energy barrier layer, so as to avoid affecting the service life of the component.

[0030] After the element is powered on, the electrons on the N-type doped side will move towards the active region, and the holes on the P-type doped side will move towards the active region. The electron-hole recombination process is shown in the figure. Figure 5 As can be seen from the figure, Figure 5 It can be seen that the energy band value corresponding to each layer in the active layer structure in the embodiment of the present application is overall in an asymmetric distribution, which can restrain the electrons with high mobility on the N-type doped side, or in other words, increase the distance of the electron movement, can effectively prevent the electrons from crossing the energy barrier layer in the active region to reach the confinement layer on the P-type doped side, thereby preventing abnormal service life caused by high temperature or high current operation of the component; on the other hand, the probability of the electrons and holes meeting in the active region is also increased, thereby increasing the carrier recombination probability and improving the internal quantum efficiency.

[0031] ​This application embodiment also provides another active layer structure, which is implemented based on the previous embodiment. This embodiment focuses on describing the specific material composition of the active layer structure.

[0032] In a preferred embodiment, the number of wells in the aforementioned composite quantum well layer is typically set to an odd number. By setting an odd number of wells 132, the two sides of the highest point of the electric field can be made symmetrical, and the electric field can be centered, thereby maximizing both the overall internal quantum efficiency and the external quantum efficiency of the device itself. If the electric field is not centered but biased to one side, it means that the place where electrons and holes meet is biased to one side, and the middle position of the active region is not the region with the most electron-hole recombination, which means that the quantum efficiency is lower.

[0033] The following is an example of an active layer structure with three well layers and four energy barrier layers. See also... Figure 6 As shown, the active layer structure includes, from bottom to top, an N-type doped layer 11, a first confinement layer 12, a composite quantum well layer 13, a second confinement layer 14, and a P-type doped layer 15; wherein, the composite quantum well layer 13 includes, from bottom to top, a first energy barrier layer 131, a first well layer 132, a second energy barrier layer 133, a second well layer 134, a third energy barrier layer 135, a third well layer 136, and a fourth energy barrier layer 137; wherein, the band value of the second energy barrier layer 133 is higher than the band values ​​of the other energy barrier layers; the band value corresponding to the first confinement layer 12 is higher than the band value corresponding to the second confinement layer 14.

[0034] The aforementioned N-type doped layer 11 includes a first N-doped layer 111, a second N-doped layer 112, and a third N-doped layer 113 arranged sequentially from bottom to top; the energy band value corresponding to the third N-doped layer 113 is less than the energy band value corresponding to the first N-doped layer 111, and greater than the energy band value corresponding to the second N-doped layer 112.

[0035] The aforementioned P-type doped layer 15 includes: a first P-doped layer 151 and a second P-doped layer 152 arranged sequentially from bottom to top; the band value corresponding to the second P-doped layer 152 is greater than the band value corresponding to the first P-doped layer 151.

[0036] The band values ​​of the first N-doped layer 111, the second energy barrier layer 133, the second confinement layer 14, and the second P-doped layer 152 are all the same; the band values ​​of the third N-doped layer 113, the first energy barrier layer 131, the third energy barrier layer 135, and the fourth energy barrier layer 137 are all the same.

[0037] See Table 1 for the materials used in each layer and their corresponding band values:

[0038] Table 1

[0039]

[0040] The materials corresponding to the first N-doped layer, the second N-doped layer and the third N-doped layer are respectively Al (0.9) Ga (0.1) As, Al (0.1) Ga (0.9) As and Al (0.3) Ga (0.7) As, and the band values are respectively 2.128eV, 1.547eV and 1.796eV.

[0041] The materials corresponding to the first P-doped layer and the second P-doped layer are respectively Al (0.7) Ga (0.3) As and Al (0.9) Ga (0.1) As, and the band values are respectively 2.058eV and 2.128eV.

[0042] The materials corresponding to the first confinement layer and the second confinement layer are respectively Al (0.35) Ga (0.65) As, Al (0.9) Ga (0.1) As, and the band values are respectively 1.859eV and 2.128eV.

[0043] The materials corresponding to the first well layer, the second well layer and the third well layer are all In (0.1) Ga (0.9) As, and the band values are all 1.279eV.

[0044] The materials corresponding to the first energy barrier layer, the third energy barrier layer and the fourth energy barrier layer are all Al (0.3) Ga (0.7) As, and the band values are all 1.796eV; the material corresponding to the second energy barrier layer is Al (0.9) Ga (0.1) As, and the band value is 2.128eV.

[0045] Figure 7 The band diagram corresponding to the above band values provided by the embodiments of the present application is shown in the following figure: Figure 7 It can be seen that the band values of each layer in the active layer structure in the embodiments of the present application are distributed in a non-symmetrical form as a whole, which can restrain the electrons with faster mobility on the N-doped side, or in other words, increase the distance of electron movement, and can effectively prevent the electrons from crossing the energy barrier layer in the active region to reach the confinement layer on the P-doped side, thereby preventing abnormal service life caused by high temperature or high current operation of the component; on the other hand, it can also increase the probability of recombination of electrons and holes in the active region, thereby increasing the probability of recombination of carriers and improving the internal quantum efficiency.

[0046] ​Figure 8 As shown in the simulation diagram, the active layer structure provided in the embodiment of the present application can obtain higher electric field intensity in the active region relative to the conventional structure.

[0047] Based on the above-mentioned active layer structure embodiment, the embodiment of the present application further provides a surface-emitting resonant cavity laser, as shown in the figure. Figure 9 As shown in the figure, the surface-emitting resonant cavity laser comprises, from bottom to top, a substrate 21, a buffer layer 22, an N-type Bragg reflection layer 23, the active layer structure 24 as described in the above-mentioned embodiment, an oxidation layer 25, and a P-type Bragg reflection layer 26.

[0048] The surface-emitting resonant cavity laser provided in the embodiment of the present application has the same implementation principle and technical effects as the above-mentioned active layer structure embodiment. For brief description, the part of the embodiment of the surface-emitting resonant cavity laser not mentioned can refer to the corresponding content in the above-mentioned active layer structure embodiment.

[0049] In the description of the present application, it should be noted that the orientations or position relationships indicated by the terms “center”, “upper”, “lower”, “left”, “right”, “vertical”, “horizontal”, “inner”, “outer” and the like are the orientations or position relationships shown in the figures, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms “first”, “second”, “third” are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0050] Finally, it should be noted that: the above-mentioned embodiments are only specific embodiments of the present application, which are used to illustrate the technical solutions of the present application, but not to limit the present application, the protection scope of the present application is not limited to this, although the present application has been described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that any person skilled in the art within the technical range disclosed by the present application can modify or easily think of changes to the technical solutions recorded in the above-mentioned embodiments, or make equivalent replacement to part of the technical features; and these modifications, changes or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and all should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An active layer structure, characterized by The active layer structure comprises, from bottom to top, an N-doped layer, a first confinement layer, a composite quantum well layer, a second confinement layer and a P-doped layer; wherein the composite quantum well layer comprises barrier layers and well layers arranged alternately; the number of the barrier layers is equal to the number of the well layers plus one; the corresponding energy band values of each layer in the active layer structure are distributed in a non-symmetrical form as a whole; the number of the well layers in the composite quantum well layer is odd. The composite quantum well layer comprises, from bottom to top, a first barrier layer, a first well layer, a second barrier layer, a second well layer, a third barrier layer, a third well layer and a fourth barrier layer; wherein the energy band value of the second barrier layer is higher than that of the other barrier layers; the energy band value of each barrier layer is higher than that of each well layer.

2. The active layer structure according to claim 1, characterized in that The energy band value corresponding to the first confinement layer is higher than that corresponding to the second confinement layer.

3. The active layer structure according to claim 2, characterized in that The N-doped layer comprises, from bottom to top, a first N-doped layer, a second N-doped layer and a third N-doped layer; the energy band value corresponding to the third N-doped layer is lower than that corresponding to the first N-doped layer and higher than that corresponding to the second N-doped layer.

4. The active layer structure according to claim 3, characterized in that The P-doped layer comprises, from bottom to top, a first P-doped layer and a second P-doped layer; the energy band value corresponding to the second P-doped layer is higher than that corresponding to the first P-doped layer.

5. The active layer structure according to claim 4, characterized in that The energy band values of the first N-doped layer, the second barrier layer, the second confinement layer and the second P-doped layer are the same; the energy band values of the third N-doped layer, the first barrier layer, the third barrier layer and the fourth barrier layer are the same.

6. The active layer structure of claim 3, wherein The first N-doped layer, the second N-doped layer and the third N-doped layer respectively correspond to materials of: Al (0.9) Ga (0.1) As, Al (0.1) Ga (0.9) As and Al (0.3) Ga (0.7) As.

7. The active layer structure of claim 4, wherein The first P-doped layer and the second P-doped layer respectively correspond to materials of: Al (0.7) Ga (0.3) As and Al (0.9) Ga (0.1) As.

8. An edge emitting resonator laser, comprising: The surface-emitting resonant cavity laser comprises, from bottom to top, a substrate, a buffer layer, an N-type Bragg reflection layer, the active layer structure according to any one of claims 1-7, an oxidation layer and a P-type Bragg reflection layer.

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