JP5382289B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light emitting device.

A super luminescent diode (SLD) is a light emitting device capable of obtaining an output comparable to that of a semiconductor laser while exhibiting low coherency as in the case of a light emitting diode. However, since the element length generally ranges from several hundred μm to several mm, the SLD has a large parasitic capacitance and is not suitable for applications that require the intensity of emitted light to be changed at high speed. To deal with this problem, for example, in Patent Document 1, a control current injection region is provided behind the light emitting surface.
JP-A-10-84130

  One of the objects of the present invention is to provide a light-emitting device capable of efficiently controlling the intensity of emitted light.

The light emitting device according to the present invention is
A first cladding layer;
An active layer formed above the first cladding layer;
A second cladding layer formed above the active layer;
A first electrode electrically connected to the first cladding layer;
A second electrode electrically connected to the second cladding layer;
Including
A part of the active layer constitutes a gain region,
The gain region includes a first gain portion and a second gain portion separated from the first gain portion and a connection portion;
The second gain portion has an emission end face that emits light;
At least one of the first electrode and the second electrode has a first portion and a second portion electrically separated from the first portion,
The first portion is an electrode for injecting a current into the first gain portion;
The second portion is an electrode for injecting a current into the second gain portion.

  The light emitting device according to the present invention can efficiently control the intensity of emitted light.

  In the description of the present invention, the word “upper” is, for example, “forms another specific thing (hereinafter referred to as“ B ”)“ above ”a specific thing (hereinafter referred to as“ A ”)”. Etc. In the description according to the present invention, in the case of this example, the case where B is directly formed on A and the case where B is formed on A via another are included. The word “upward” is used.

  Further, in the description of the present invention, the term “electrically connected” refers to, for example, another specific member (hereinafter referred to as “electrically connected” to “specific member (hereinafter referred to as“ C member ”)”. It is used as "D member"). In the description according to the present invention, in the case of this example, the case where the C member and the D member are directly connected and electrically connected, and the C member and the D member are the other members. The term “electrically connected” is used as a case where the case where the terminals are electrically connected to each other is included.

In the light emitting device according to the present invention,
The gain region has an end surface on the first side surface side of the active layer, and an end surface on the second side surface side of the active layer parallel to the first side surface,
In the gain region, when viewed from the first side surface side, the end surface on the first side surface side and the end surface on the second side surface side do not overlap,
At least the end surface on the second side surface side may be the emission end surface.

In the light emitting device according to the present invention,
Light that is not laser light can be emitted.

In the light emitting device according to the present invention,
The area of the second gain portion may be smaller than the area of the first gain portion.

In the light emitting device according to the present invention,
The layer structure constituting the second gain portion may be different from the layer structure constituting the first gain portion.

In the light emitting device according to the present invention,
The quantum well structure constituting the second gain portion may be different from the quantum well structure constituting the first gain portion.

In the light emitting device according to the present invention,
The reflectance of the first side surface is higher than the reflectance of the second side surface in the wavelength band of light generated in the gain region,
A plurality of the gain regions are provided,
The plurality of gain regions form at least one gain region pair;
One first gain region of the pair of gain regions is provided toward one direction;
The other second gain region of the pair of gain regions is provided in another direction different from the one direction;
At least a part of the end surface of the first gain region on the first side surface side may overlap with at least a part of the end surface of the second gain region on the first side surface side.

In the light emitting device according to the present invention,
A plurality of gain region pairs may be arranged.

In the light emitting device according to the present invention,
The first electrode is in contact with the first layer in ohmic contact;
The second electrode is in contact with the second layer in ohmic contact;
At least one of the contact surface between the first electrode and the first layer and the contact surface between the second electrode and the second layer may have the same planar shape as the gain region.

In the light emitting device according to the present invention,
At least one of the first layer and the second layer constitutes at least a part of a columnar part,
The columnar portion has a planar shape obtained by combining the planar shape of the gain region and the planar shape of the connection portion,
An insulating part is provided on the side of the columnar part,
The insulating portion may be in contact with the side surface of the columnar portion between the first side surface and the second side surface as viewed in a plan view.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

1. 1. First embodiment 1.1. First, the light emitting device 100 according to the first embodiment will be described. 1 is a perspective view schematically showing the light emitting device 100, FIG. 2 is a plan view schematically showing the light emitting device 100, and FIG. 3 is a schematic view of the light emitting device 100 in FIG. 4 is a cross-sectional view taken along line -III, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. In FIG. 1, members other than the active layer 108 are not shown for convenience. Here, a case where the light emitting device 100 is an InGaAlP-based (red) semiconductor light emitting device will be described.

  As shown in FIGS. 1 to 4, the light emitting device 100 includes a first cladding layer 106, an active layer 108, a second cladding layer 110, a first electrode 120, and a second electrode 122. The light emitting device 100 can further include, for example, a substrate 102, a buffer layer 104, and a contact layer 112.

  As the substrate 102, for example, a first conductivity type (for example, n-type) GaAs substrate or the like can be used. The substrate 102 can be a layer in ohmic contact with the first electrode 120.

  The buffer layer 104 can be formed on the substrate 102 as shown in FIGS. 3 and 4, for example. As the buffer layer 104, for example, a GaAs layer of the first conductivity type, an InGaP layer, or the like can be used. The buffer layer 104 can improve the crystallinity of the first cladding layer 106, for example.

  The first cladding layer 106 is formed on the buffer layer 104. The first cladding layer 106 is made of, for example, a first conductivity type semiconductor. As the first cladding layer 106, for example, an n-type AlGaP layer can be used.

  The active layer 108 is formed on the first cladding layer 106. The active layer 108 has, for example, a multiple quantum well (MQW) structure in which three quantum well structures each composed of an InGaP well layer and an InGaAlP barrier layer are stacked.

  The shape of the active layer 108 is, for example, a rectangular parallelepiped (including a cube). As shown in FIGS. 1 and 2, the active layer 108 has a first side surface 107 and a second side surface 109. The first side surface 107 and the second side surface 109 are parallel.

  A part of the active layer 108 constitutes a gain region 180. The number of gain regions 180 is not particularly limited. The gain region 180 can produce light, which can receive gain within the gain region 180. As shown in FIG. 2, the gain region 180 is provided in a direction inclined with respect to the normal line P of the first side surface 107 as viewed in plan. Thereby, laser oscillation of light generated in the gain region 180 can be suppressed or prevented. Although not shown, the gain region 180 may have a curved portion.

  As shown in FIGS. 1 and 2, the gain region 180 includes a first end face 170 provided on the first side face 107 side of the active layer 108 and a second end face provided on the second side face 109 side of the active layer 108. 172. At least the second end face 172 is an emission end face that emits light. Although not shown, the gain region 180 may not have the first end surface 170 provided on the first side surface 107. That is, the gain region 180 can be provided so as not to reach the first side surface 107. Thereby, the emission of light from the first side surface 107 can be suppressed. In the wavelength band of light generated in the gain region 180, for example, the reflectance of the first side surface 107 can be made higher than the reflectance of the second side surface 109. Thereby, the emission of light from the first end face 170 can be suppressed.

  The gain region 180 includes a first gain portion 181 and a second gain portion 182 separated by the first gain portion 181 and the connection portion 190. The first gain portion 181, the connection portion 190, and the second gain portion 182 can be continuously provided on a straight line as shown in FIGS. 1 and 2. The width a of the first gain portion 181 and the width b of the second gain portion 182 may be the same as shown in FIG. The planar shape of the first gain portion 181 and the second gain portion 182 may be a parallelogram. Different voltages can be applied to the first gain portion 181 and the second gain portion 182, respectively. That is, the first gain portion 181 and the second gain portion 182 can control the amount of injected current independently. The second gain portion 182 has a second end face 172 that is an emission end face that emits light. The area of the second gain portion 182 can be made smaller than the area of the first gain portion 181. Thereby, although a reason is mentioned later, in the light-emitting device 100, the intensity | strength of the emitted light can be controlled efficiently.

  The connection portion 190 is a region constituted by a part of the active layer 108. As shown in FIGS. 1, 2, and 4, the connecting portion 190 is a region sandwiched between the first gain portion 181 and the second gain portion 182. The width of the connection portion 190 may be the same as the width a of the first gain portion 181 and the width b of the second gain portion 182 as shown in FIG. The planar shape of the connecting portion 190 can be a parallelogram. As shown in FIGS. 2 and 4, the second electrode 122 may not be formed above the connection portion 190. The connection portion 190 may be a region having a smaller area than the first gain portion 181 and the second gain portion 182.

  The detailed functions of the first gain portion 181, the second gain portion 182 and the connection portion 190 will be described later.

  FIG. 5 is a plan view of the active layer 108 in the example of FIGS. 1 to 4 as seen from the first side face 107 side. As shown in FIG. 5, the gain region 180 does not overlap the first end surface 170 and the second end surface 172. Thereby, the light generated in the gain region 180 can be prevented from being subjected to multiple reflection directly between the first end surface 170 and the second end surface 172. As a result, since a direct resonator cannot be formed, laser oscillation of light generated in the gain region 180 can be more reliably suppressed or prevented. Therefore, the light emitting device 100 can emit light that is not laser light. In this case, as shown in FIG. 5, for example, in the gain region 180, the shift width c between the first end surface 170 and the second end surface 172 may be a positive value.

  As shown in FIGS. 3 and 4, the second cladding layer 110 is formed on the active layer 108. The second cladding layer 110 is made of, for example, a second conductivity type (eg, p-type) semiconductor. For example, a p-type AlGaP layer can be used for the second cladding layer 110.

  For example, the p-type second cladding layer 110, the active layer 108 not doped with impurities, and the n-type first cladding layer 106 constitute a pin diode. Each of the first cladding layer 106 and the second cladding layer 110 is a layer having a larger forbidden band width and a smaller refractive index than the active layer 108. The active layer 108 has a function of amplifying light. The first cladding layer 106 and the second cladding layer 110 have a function of confining injected carriers (electrons and holes) and light with the active layer 108 interposed therebetween.

  In the light emitting device 100, when a forward bias voltage of a pin diode is applied between the first electrode 120 and the second electrode 122, recombination of electrons and holes occurs in the gain region 180 of the active layer 108. This recombination causes light emission. With this generated light as a starting point, stimulated emission occurs in a chain, and the light intensity is amplified in the gain region 180. For example, the intensity 10 of the light 10 generated in the gain region 180 can be amplified until it reaches the second end face 172 as shown in FIG. And it is radiate | emitted as the emitted light 130 from the 2nd end surface 172. FIG.

  Here, specific functions of the first gain portion 181, the second gain portion 182 and the connection portion 190 will be described.

  As described above, the first gain portion 181 and the second gain portion 182 can control the amount of injected current independently. That is, for example, a part of the light 10 generated in the first gain portion 181 receives different gains (gain amounts) in the first gain portion 181 and the second gain portion 182, and thus from the second end surface 172. Can be emitted. Specifically, the intensity of light emitted from the second end surface 172 can be controlled by changing the voltage applied to the second gain portion 182 to change the amount of current injected into the second gain portion 182. it can. That is, the gain amount of the entire gain region 180 can be controlled by adjusting the gain amount of the second gain portion 182. For example, when it is desired to increase the intensity of the emitted light, a voltage higher than that of the first gain portion 181 is applied to the second gain portion 182. For example, when it is desired to reduce the intensity of emitted light, a voltage smaller than that of the first gain portion 181 is applied to the second gain portion 182 or no voltage is applied to the second gain portion 182.

  As described above, the connection portion 190 is provided between the first gain portion 181 and the second gain portion 182. For example, the connection portion 190 may have a small area that does not cause a decrease in intensity with respect to light passing through the connection portion 190.

  The contact layer 112 can be formed on the second cladding layer 110, for example, as shown in FIGS. As the contact layer 112, a layer in ohmic contact with the second electrode 122 can be used. The contact layer 112 is made of, for example, a second conductivity type semiconductor. As the contact layer 112, for example, a p-type GaAs layer can be used.

  The first electrode 120 is formed on the entire lower surface of the substrate 102. The first electrode 120 is electrically connected to the first cladding layer 106 via the substrate 102 and the buffer layer 104. The first electrode 120 is one electrode for driving the light emitting device 100. As the first electrode 120, for example, an electrode in which a Cr layer, an AuGe layer, a Ni layer, and an Au layer are stacked in this order from the substrate 102 side can be used. Note that a second contact layer (not shown) is provided between the first cladding layer 106 and the buffer layer 104, the second contact layer is exposed by dry etching or the like, and the first electrode 120 is placed on the second contact layer. It can also be provided. Thereby, a single-sided electrode structure can be obtained. This form is particularly effective when the substrate 102 is insulative. In this embodiment, for example, a semi-insulating GaAs substrate can be used as the substrate 102. For example, an n-type GaAs layer can be used as the second contact layer. Although not shown, the substrate 102 and a member provided thereon can be separated using, for example, an epitaxial lift-off (ELO) method, a laser lift-off method, or the like. That is, the light emitting device 100 may not have the substrate 102. In this case, for example, the first electrode 120 can be formed directly below the buffer layer 104. This form is also particularly effective when the substrate 102 is insulative.

  The second electrode 122 is formed on the contact layer 112. The second electrode 122 is electrically connected to the second cladding layer 110 through the contact layer 112. The second electrode 122 is the other electrode for driving the light emitting device 100. As the second electrode 122, for example, an electrode in which a Cr layer, an AuZn layer, and an Au layer are stacked in this order from the contact layer 112 side can be used. As shown in FIG. 2, the lower surface of the second electrode 122 has a planar shape similar to that of the gain region 180. In other words, in the illustrated example, the current path between the electrodes 120 and 122 is determined by the planar shape of the lower surface of the second electrode 122, and as a result, the planar shape of the gain region 180 of the active layer 108 is determined. is there. Alternatively, after an insulating layer (not shown) is formed on the contact layer 112, the insulating layer is removed so as to have a planar shape similar to that of the gain region 180, and the contact layer 112 is exposed, so that the second electrode 122 is formed. It may be formed so as to be in contact with at least the exposed contact layer 112. Although not shown, for example, the upper surface of the first electrode 120 may have the same planar shape as the gain region 180.

  The second electrode 122 includes, for example, a first portion 124 and a second portion 126 that is electrically separated from the first portion 124. The first portion 124 is an electrode for injecting current into the first gain portion 181. The second portion 126 is an electrode for injecting current into the second gain portion 182. The first portion 124 may be formed above the first gain portion 181. The second portion 126 may be formed above the second gain portion 182. Although not shown, not the second electrode 122 but the first electrode 120 may have the first portion 124 and the second portion 126. Further, both the first electrode 120 and the second electrode 122 may have a first portion 124 and a second portion 126.

  The light emitting device according to the present embodiment can be applied to a light source such as a projector, a display, a lighting device, a measurement device, a communication device, and the like. The same applies to the embodiments described later.

  In the example of the light emitting device 100, the case of the InGaAlP system has been described. However, in the present invention, any material system capable of forming a light emission gain region can be used. As the semiconductor material, for example, semiconductor materials such as AlGaN, InGaN, GaAs, InGaAs, GaInNAs, and ZnCdSe can be used. As the substrate 102, for example, a GaN substrate can also be used. Further, for example, an organic material can be used. The same applies to the modifications and embodiments described later.

  For example, the light emitting device 100 has the following characteristics.

  In the light emitting device 100, the intensity of light emitted from the second end face 172 can be controlled by changing the voltage applied to the second gain portion 182 to change the amount of current injected into the second gain portion 182. it can. That is, the gain amount of the entire gain region 180 can be controlled by adjusting the gain amount of the second gain portion 182. The second gain portion 182 may have a second end face 172 that is a light exit end face. That is, the second gain portion 182 is provided in contact with the second end surface 172. Thereby, the light emitting device 100 can increase the amount of change in the intensity of the emitted light (for example, an extinction ratio described later). That is, in the light emitting device 100, the intensity of the emitted light can be controlled efficiently. It is known that the light emitting device 100 can efficiently control the intensity of emitted light when the second gain portion 182 is provided in contact with the second end face 172 as in an experimental example described later.

  In the light emitting device 100, the area of the second gain portion 182 is smaller than the area of the first gain portion 181. Therefore, the second gain portion 182 has a smaller parasitic capacitance than the first gain portion 181. Thereby, in the light emitting device 100, since the amount of current injected into the second gain portion 182 having a small area is changed, the intensity of emitted light can be changed at high speed. That is, in the light emitting device 100, the intensity of the emitted light can be controlled efficiently. Further, since the current injection amount of the second gain portion 182 having a small area is controlled, for example, a driving IC for large current becomes unnecessary. Therefore, the light emitting device 100 can control the intensity of light emitted at low cost.

  In the light emitting device 100, as described above, laser oscillation of light generated in the gain regions 180 and 182 can be suppressed or prevented. Therefore, speckle noise can be reduced.

1.2. Manufacturing Method of Light Emitting Device According to First Embodiment Next, a manufacturing method of the light emitting device 100 according to the first embodiment will be described with reference to the drawings. 6 is a cross-sectional view schematically showing a manufacturing process of the light emitting device 100, and corresponds to the cross-sectional view shown in FIG.

  As shown in FIG. 6, for example, the buffer layer 104, the first cladding layer 106, the active layer 108, the second cladding layer 110, and the contact layer 112 are epitaxially grown on the substrate 102 in this order. As a method for epitaxial growth, for example, MOCVD (Metal-Organic Chemical Vapor Deposition) method, MBE (Molecular Beam Epitaxy) method or the like can be used.

  As shown in FIG. 3, for example, the second electrode 122 is formed on the contact layer 112. The second electrode 122 is formed, for example, by forming a conductive layer on the entire surface by a vacuum evaporation method and then patterning the conductive layer using a photolithography technique and an etching technique. For example, the second electrode 122 is patterned to include a first portion 124 and a second portion 126. The second electrode 122 can also be formed in a desired shape by, for example, a combination of a vacuum deposition method and a lift-off method.

  Next, the first electrode 120 is formed under the lower surface of the substrate 102. The manufacturing method of the 1st electrode 120 is formed with the manufacturing method same as the illustration of the manufacturing method of the 2nd electrode 122 mentioned above, for example. Note that the order of forming the first electrode 120 and the second electrode 122 is not particularly limited.

  Through the above steps, the light emitting device 100 is obtained.

  According to the method for manufacturing the light emitting device 100, the light emitting device 100 capable of efficiently controlling the intensity of emitted light can be obtained.

1.3. Experimental Example of Light-Emitting Device According to First Embodiment Next, an experimental example of the light-emitting device 100 according to the first embodiment will be described with reference to the drawings. Specifically, the simulation in the model M that models the gain region 180 of the light emitting device 100 will be described. FIG. 7 is a cross-sectional view schematically showing the model M used in the simulation, and corresponds to a cross-sectional view taken along the line VII-VII in FIG. FIG. 8 is a graph showing the result of simulation in the model M.

  First, the model M used for the simulation will be described.

  As the model M, a gain region 180 including a first gain portion 181 and a second gain portion 182 is used as shown in FIG. In the model M, the connecting portion 190 is omitted. In the model M, the length of the gain region 180 is L (that is, the length of the model M is L). That is, in the model M, the first end face 170 is located at the origin 0 and the second end face 172 is located at the distance L on the X axis along the gain region 180. The second end face 172 is an emission end face that emits the emitted light 130. In the model M, the length of the second gain portion 182 is d, and the second gain portion 182 is moved in the gain region 180 from the origin 0 to a distance (Ld). That is, the second gain portion 182 is in contact with the first end face 170 at the origin 0 and is in contact with the second end face 172 at a distance (Ld). The gain constants of the first gain portion 181 and the second gain portion 182 were G1 and G2, respectively. The value of each parameter was set such that L was 1000 μm, d was 100 μm, and G1 and G2 were variable.

  Next, the simulation result will be described.

In FIG. 8, the horizontal axis represents the movement distance X of the second gain portion 182 described above, and the vertical axis represents the extinction ratio R of the model M. That is, FIG. 8 is a graph plotting the extinction ratio R when the second gain portion 182 moves from the origin 0 to the distance (Ld) in the model M. Extinction ratio R, to the intensity _{I off} of emitted light when the the G1 30 cm ^-1 and G2 is set to -10 cm ^-1, is emitted when the a G1 30 cm ^-1 and G2 is set to 30 cm ^-1 Is the value of the light intensity I _on . When the extinction ratio R is expressed by a formula, the following formula is obtained.

R = [I _on (G1; 30, G2; 30)] / [I _off (G1; 30, G2; −10)]
That is, it can be said that the greater the extinction ratio R, the greater the amount of change in the intensity of the emitted light. That is, the larger the extinction ratio R, the more efficiently the model M can control the intensity of emitted light.

  As shown in FIG. 8, the larger the distance X, the larger the extinction ratio R, and the maximum extinction ratio R at the distance (Ld). That is, according to the present simulation, it was found that the intensity of the emitted light can be controlled most efficiently when the second gain portion 182 contacts the second end face 172 that is the exit end face.

1.4. Next, a light emitting device 150 according to a modification of the first embodiment will be described with reference to the drawings. 9 is a plan view schematically showing the light emitting device 150, and FIG. 10 is a cross-sectional view taken along the line XX of FIG. Hereinafter, in the light emitting device 150 according to the modification of the first embodiment, members having the same functions as those of the constituent members of the light emitting device 100 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is given. Is omitted.

  The light emitting device 150 can have an active layer 158 having a layer structure different from that of the active layer 108 as shown in FIGS. At least a part of the active layer 108 may constitute the first gain portion 181, and at least a part of the active layer 158 may constitute the second gain portion 182. That is, the layer structure constituting the second gain portion 182 can be different from the layer structure constituting the first gain portion 181. For example, the quantum well structure constituting the second gain portion 182 can be different from the quantum well structure constituting the first gain portion 181. More specifically, the first gain portion 181 has a multiple quantum well structure in which three quantum well structures each composed of an InGaP well layer and an InGaAlP barrier layer are stacked, whereas the second gain portion 182 includes: One quantum well structure or a multiple quantum well structure in which five quantum well structures are stacked can be provided. Further, the second gain portion 182 can be composed of only a single layer of, for example, an InGaAlP layer. For example, the first gain portion 181 and the second gain portion 182 may be made of different materials. Although not shown, the planar shape of the active layer 158 may be the same as the planar shape of the second gain portion 182. Further, the connecting portion 190 may be composed of both the active layer 108 and the active layer 158 as shown, or may be composed of only one of them.

  Next, a method for manufacturing the light emitting device 150 will be described with reference to the drawings. FIG. 11 is a cross-sectional view schematically showing a manufacturing process of the light-emitting device 150, and corresponds to the cross-sectional view shown in FIG.

  As shown in FIG. 11, a region on the contact layer 112 other than the region where the active layer 158 is formed is covered with a mask layer 152 such as a photoresist. Next, for example, the contact layer 112, the second cladding layer 110, the active layer 108, and the first cladding layer 106 are removed by a known etching technique or the like to form the opening 154. Although not shown, part of the buffer layer 104 and the substrate 102 may be removed. Thereafter, the mask layer 152 is removed by, for example, a known method.

  As shown in FIG. 10, for example, the first cladding layer 106, the active layer 158, the second cladding layer 110, and the contact layer 112 are epitaxially grown in this order in the opening 154. As a method of epitaxial growth, for example, MOCVD method, MBE method or the like can be used. The epitaxial growth can be performed so that the active layer 158 has a different layer structure from the active layer 108.

  Through the above steps, the light-emitting device 150 is obtained.

  In addition to the features of the light emitting device 100, the light emitting device 150 has the following features, for example.

  In the light emitting device 150, the layer structure constituting the second gain portion 182 can be different from the layer structure constituting the first gain portion 181. Therefore, the gain constant and internal loss of the second gain portion 182 can be changed. For example, the intensity of the emitted light can be controlled more efficiently by making the gain constant of the second gain portion 182 larger than the gain constant of the first gain portion 181.

2. Second Embodiment 2.1. Light Emitting Device According to Second Embodiment Next, a light emitting device 200 according to a second embodiment will be described. FIG. 12 is a perspective view schematically showing the light emitting device 200, and FIG. 13 is a plan view schematically showing the light emitting device 200. Hereinafter, in the light emitting device 200 according to the second embodiment, members having the same functions as the constituent members of the light emitting device 100 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. . In FIG. 12, illustration of members other than the active layer 108 and the reflection portion 227 is omitted for convenience.

The reflectance of the first side surface 107 can be higher than the reflectance of the second side surface 109 in the wavelength band of light generated in the gain region 180. For example, as shown in the figure, high reflectance can be obtained by covering the first side surface 107 with the reflecting portion 227. The reflection unit 227 is, for example, a dielectric multilayer mirror. More specifically, as the reflecting portion 227, for example, a mirror in which four pairs are stacked in the order of the Al ₂ O ₃ layer and the TiO ₂ layer from the first side face 107 side can be used. In this case, the reflectance of the first side surface 107 is, for example, 90%. The reflectance of the first side surface 107 is desirably 100% or close thereto. On the other hand, the reflectance of the second side surface 109 is desirably 0% or close thereto. For example, a low reflectance can be obtained by covering the second side surface 109 with an antireflection portion (not shown). As the antireflection part, for example, an Al ₂ O ₃ single layer can be used. The reflection portion 227 and the antireflection portion are formed by, for example, a CVD (Chemical Vapor Deposition) method, a sputtering method, an ion assisted deposition (Ion Assisted Deposition) method, or the like. In addition, the formation order of the reflection part 227 and an antireflection part is not specifically limited. The material of the reflective portion and the anti-reflection portion is not particularly limited, for _example, can be used SiO 2, SiN, or the like _Ta 2 _{O 5.}

  In the light emitting device 200, a plurality of gain regions 180 are provided. In the illustrated example, two gain regions 180 (first gain region 281 and second gain region 282) are shown, but the number is not particularly limited. The first gain region 281 and the second gain region 282 constitute a gain region pair 280. As shown in FIG. 13, the first gain region 281 and the second gain region 282 are provided in a direction inclined with respect to the normal line P of the first side surface 107 as seen in a plan view. The first gain region 281 and the second gain region 282 are provided in different directions. In the illustrated example, the first gain region 281 is inclined in one direction with respect to the perpendicular P, and is provided in the first direction A having an inclination of the angle θ. The second gain region 282 is inclined to the other side with respect to the perpendicular line P, and is provided toward the second direction B having an inclination of the angle θ. The first end surface 170 of the first gain region 281 and the first end surface 170 of the second gain region 282 can overlap each other on the overlapping surface 270. In the illustrated example, the first end face 170 of the first gain region 281 and the first end face 170 of the second gain region 282 are completely overlapped, but at least a part thereof may be overlapped. Each of the first gain region 281 and the second gain region 282 may have a first gain portion 181 and a second gain portion 182.

  In the light emitting device 200, for example, as illustrated in FIG. 12, a part 20 of the light generated in the first gain region 281 is reflected by the overlapping surface 270 and emitted from the second end surface 172 of the second gain region 282. The light intensity is amplified in the meantime. Similarly, part of the light generated in the second gain region 282 is reflected by the overlapping surface 270 and is emitted as the emitted light 130 from the second end surface 172 of the first gain region 281, but the light intensity is amplified during that time. Is done. Note that some of the light generated in the first gain region 281 is directly emitted from the second end surface 172 of the first gain region 281. Similarly, some of the light generated in the second gain region 282 is directly emitted from the second end surface 172 of the second gain region 282.

  In addition to the features of the light emitting device 100, the light emitting device 200 has the following features, for example.

  The light emitting device 200 includes a first gain region 281 and a second gain region 282 that constitute a gain region pair 280. The first end surface 170 of the first gain region 281 and the first end surface 170 of the second gain region 282 can overlap each other on the overlapping surface 270. Thereby, for example, a part of the light 20 generated in the first gain region 281 can travel while receiving gain in the first gain region 281 and the second gain region 282 and can be emitted to the outside. Therefore, the light emitting device 200 can increase the intensity of the emitted light as compared with the case where the gain can be received only within one gain region 180.

2.2. Method for Manufacturing Light-Emitting Device According to Second Embodiment The method for manufacturing light-emitting device 200 according to the second embodiment is basically the same as the method for manufacturing light-emitting device 100 according to the first embodiment. Therefore, the description is omitted.

3. Third Embodiment 3.1. Light Emitting Device According to Third Embodiment Next, a light emitting device 300 according to a third embodiment will be described. FIG. 14 is a perspective view schematically showing the light emitting device 300, and FIG. 15 is a plan view schematically showing the light emitting device 300. Hereinafter, in the light emitting device 300 according to the third embodiment, members having the same functions as the constituent members of the light emitting device 200 according to the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. . In FIG. 14, members other than the active layer 108 and the reflection portion 227 are not shown for convenience.

  The light emitting device 300 can have a plurality of gain region pairs 280. The light emitting device 300 can be configured by arranging a plurality of gain region pairs 280. In the illustrated example, the second end surface 172 of the first gain region 281 and the second end surface 172 of the second gain region 282 overlap, but do not have to overlap.

  Since the light emitting device 300 includes the plurality of gain region pairs 280, the intensity of the emitted light can be further increased.

3.2. Method for Manufacturing Light Emitting Device According to Third Embodiment A method for manufacturing light emitting device 300 according to the third embodiment is basically the same as the method for manufacturing light emitting device 100 according to the first embodiment. Therefore, the description is omitted.

4). Fourth Embodiment 4.1. Light Emitting Device According to Fourth Embodiment Next, a light emitting device 400 according to a fourth embodiment will be described. 16 is a plan view schematically showing the light emitting device 400, and FIG. 17 is a cross sectional view schematically showing the light emitting device 400, which is a cross sectional view taken along the line XVII-XVII in FIG. Hereinafter, in the light emitting device 400 according to the fourth embodiment, members having the same functions as the constituent members of the light emitting device 100 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. .

  As shown in FIGS. 16 and 17, the light emitting device 400 includes a first cladding layer 106, an active layer 108, a second cladding layer 110, a first electrode 120, a second electrode 122, an insulating portion 402, and the like. ,including. The light emitting device 400 can further include, for example, the substrate 102, the buffer layer 104, and the contact layer 112.

  The gain region 180 and the connection portion 190 constitute an active layer 108 as shown in FIG. At least the active layer 108 has a planar shape that combines the planar shape of the gain region 180 and the planar shape of the connection portion 190. For example, the first cladding layer 106, the active layer 108, the second cladding layer 110, and the contact layer 112 have a planar shape that combines the planar shape of the gain region 180 and the planar shape of the connection portion 190. For example, as shown in FIG. 17, the first cladding layer 106, the active layer 108, the second cladding layer 110, and the contact layer 112 can constitute a columnar semiconductor deposited body (hereinafter referred to as “columnar portion”) 410. .

  The insulating unit 402 is formed on the buffer layer 104, for example. For example, the insulating unit 402 covers the side surfaces of the active layer 108 other than the first end surface 170 and the second end surface 172. For example, the insulating unit 402 can cover at least the side surface of the active layer 108 between the first side surface 107 and the second side surface 109 of the active layer 108. For example, of the side surfaces of the columnar portion 410, the side surfaces other than the first side surface 107 side and the second side surface 109 side are covered with the insulating portion 402. The current between the electrodes 120 and 122 can flow through the columnar portion 410 sandwiched between the insulating portions 402, avoiding the insulating portions 402. Although not shown, for example, when a plurality of gain regions 180 are provided, the side surfaces of the active layer 108 are covered with the insulating portion 402, so that crosstalk between the gain regions 180 can be prevented.

The insulating part 402 can have a refractive index lower than that of the active layer 108, for example. Thereby, light can be efficiently confined in the active layer 108. As the insulating portion 402, for example, a SiN layer, a SiO ₂ layer, a polyimide layer, or the like can be used.

  As with the light emitting device 100, the light emitting device 400 can efficiently control the intensity of the emitted light.

4.2. Method for Manufacturing Light-Emitting Device According to Fourth Embodiment Next, a method for manufacturing a light-emitting device 400 according to the fourth embodiment will be described with reference to the drawings. Hereinafter, in the method for manufacturing the light emitting device 400 according to the fourth embodiment, members having the same functions as those of the constituent members of the method for manufacturing the light emitting device 100 according to the first embodiment are denoted by the same reference numerals, and the details thereof are described. The detailed explanation is omitted.

  18 is a cross-sectional view schematically showing a manufacturing process of the light-emitting device 400 shown in FIGS. 16 and 17, and corresponds to the cross-sectional view shown in FIG.

  As shown in FIG. 18, the buffer layer 104, the first cladding layer 106, the active layer 108, the second cladding layer 110, and the contact layer 112 are formed on the substrate 102.

  Next, for example, the first cladding layer 106, the active layer 108, the second cladding layer 110, and the contact layer 112 can be patterned. The opening by patterning can be performed, for example, to a depth that reaches at least the upper surface of the first cladding layer 106. The patterning is performed using, for example, a photolithography technique and an etching technique. By this step, the columnar section 410 can be formed.

  As shown in FIG. 17, the insulating portion 402 can be formed so as to cover the side surface of the columnar portion 410. Specifically, first, an insulating layer (not shown) is formed on the entire surface of the buffer layer 104 (including on the contact layer 112) by, for example, a CVD method or a coating method. Next, the upper surface of the contact layer 112 is exposed using, for example, an etching technique. Through the above steps, the insulating portion 402 can be obtained.

  Next, the first electrode 120 and the second electrode 122 are formed. Although not shown, the second electrode 122 may be formed on the insulating portion 402 in addition to the contact layer 112.

  Through the above steps, the light emitting device 400 is obtained.

  According to the method for manufacturing the light emitting device 400, the light emitting device 400 capable of efficiently controlling the intensity of the emitted light can be obtained in the same manner as the method for manufacturing the light emitting device 100.

  In addition, embodiment mentioned above and a modification are examples, Comprising: It is not necessarily limited to these. For example, it is possible to appropriately combine each embodiment and each modification.

  Although the embodiments of the present invention have been described in detail as described above, those skilled in the art will readily understand that many modifications are possible without substantially departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention.

The perspective view which shows typically the light-emitting device which concerns on 1st Embodiment. The top view which shows typically the light-emitting device which concerns on 1st Embodiment. 1 is a cross-sectional view schematically showing a light emitting device according to a first embodiment. 1 is a cross-sectional view schematically showing a light emitting device according to a first embodiment. FIG. 3 is a cross-sectional view schematically showing a part of the light emitting device according to the first embodiment. Sectional drawing which shows typically the manufacturing process of the light-emitting device which concerns on 1st Embodiment. Sectional drawing which shows typically the model used for the experiment example of the light-emitting device which concerns on 1st Embodiment. The graph which shows the result of the experiment example of the light-emitting device which concerns on 1st Embodiment. The top view which shows typically the light-emitting device which concerns on the modification of 1st Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on the modification of 1st Embodiment. Sectional drawing which shows typically the manufacturing process of the light-emitting device which concerns on the modification of 1st Embodiment. The perspective view which shows typically the light-emitting device which concerns on 2nd Embodiment. The top view which shows typically the light-emitting device which concerns on 2nd Embodiment. The perspective view which shows typically the light-emitting device which concerns on 3rd Embodiment. The top view which shows typically the light-emitting device which concerns on 3rd Embodiment. The top view which shows typically the light-emitting device which concerns on 4th Embodiment. Sectional drawing which shows typically the light-emitting device which concerns on 4th Embodiment. Sectional drawing which shows typically the manufacturing process of the light-emitting device which concerns on 4th Embodiment.

Explanation of symbols

10 part of light, 20 part of light, 100 light emitting device, 102 substrate, 104 buffer layer, 106 first cladding layer, 107 first side surface, 108 active layer, 109 second side surface, 110 second cladding layer, 112 Contact layer, 120 first electrode, 122 second electrode, 124 first part, 126 second part, 130 emitted light, 150 light emitting device, 152 mask layer, 154 opening, 158 active layer, 170 first end face, 172 second 2 end faces, 180 gain region, 181 first gain portion, 182 second gain portion, 190 connection portion, 200 light emitting device, 227 reflection portion, 230 outgoing light, 270 overlapping surface, 280 pair of gain regions, 281 first gain region , 282 Second gain region, 300 Light emitting device, 400 Light emitting device, 402 Insulating portion, 410 Columnar portion

Claims (11)

A first cladding layer;
A second cladding layer;
An active layer sandwiched between the first cladding layer and the second cladding layer;
Including
The active layer constitutes a gain region that generates light when current is injected;
The gain region includes a first gain portion, and a second gain portion that is positioned away from the first gain portion at a position that receives light generated in the first gain portion,
The second gain portion has an emission end face that emits light;
The gain region has an end surface on the first side surface side of the active layer, and an end surface on the second side surface side of the active layer parallel to the first side surface,
In the gain region, when viewed from the first side surface side, the end surface on the first side surface side and the end surface on the second side surface side do not overlap,
The end surface on the second side surface side is the emission end surface,
The light emitted from the emission end face is not laser light,
The quantum well structure constituting the second gain portion is different from the quantum well structure constituting the first gain portion,
The number of well layers and barrier layers of the quantum well structure of the second gain portion varies with the number of well layers and barrier layers of the quantum well structure that constitutes the first gain portion,
The light emitting device , wherein a gain constant of the second gain portion is greater than a gain constant of the first gain portion . In claim 1,
The light emitting device, wherein an area of the second gain portion is smaller than an area of the first gain portion. In claim 1 or 2,
The reflectance of the first side surface is higher than the reflectance of the second side surface in the wavelength band of light generated in the gain region,
The gain region includes a first gain region provided in one direction and a second gain region provided in another direction different from the one direction,
At least a part of the first side surface of the first gain region and at least a part of the first side surface of the second gain region overlap to form a gain region pair. , Light emitting device. In claim 3,
A light emitting device in which a plurality of gain region pairs are arranged. In any of claims 1 to 4,
A first electrode electrically connected to the first cladding layer;
A second electrode electrically connected to the second cladding layer;
A first layer in ohmic contact with the first electrode;
A second layer in ohmic contact with the second electrode;
Further comprising
At least one of the contact surface between the first electrode and the first layer and the contact surface between the second electrode and the second layer has the same planar shape as the gain region. In claim 5,
The active layer has a connection portion sandwiched between the first gain portion and the second gain portion,
At least one of the first layer and the second layer constitutes at least a part of a columnar part,
The columnar portion has a planar shape obtained by combining the planar shape of the gain region and the planar shape of the connection portion,
An insulating part is provided on the side of the columnar part,
The insulating portion is a light emitting device that is in contact with a side surface of the columnar portion between the first side surface and the second side surface as viewed in a plan view. In any one of Claims 1 thru | or 6.
The light emitting device, wherein the first gain portion and the second gain portion are positioned on a straight line. In claim 5 or 6,
At least one of the first electrode and the second electrode includes a first portion and a second portion electrically separated from the first portion. In claim 8,
The light emitting device, wherein each of the first electrode and the second electrode includes the first portion and the second portion. In claim 5 or 6,
Either one of the first electrode and the second electrode includes a first portion and a second portion electrically separated from the first portion. In any of claims 8 to 10,
The light emitting device, wherein the first part and the second part are positioned on a straight line.

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