JP2009272576A - Semiconductor light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor light-emitting device capable of efficiently extracting light emitted from a semiconductor light-emitting element to the outside. <P>SOLUTION: The semiconductor light-emitting device includes: the semiconductor light-emitting element 11; a mount 12 on which the semiconductor light-emitting element 11 is mounted; a cap 13 provided with a through-hole 16 allowed to pass light from the semiconductor light-emitting element 11 and formed so as to be widened from the side near to the semiconductor light-emitting element 11 to the side far from the element 11 to seal the semiconductor light-emitting element 11; a first translucent member 17 at least partially supported in the through-hole 16 of the cap 13 and allowed to transmit light emitted from the semiconductor light-emitting element; and a second translucent member 18 having a refractive index larger than that of the first translucent member 17, at least partially supported in the through-hole 16 of the cap 13 and allowed to transmit light from the first translucent member 17. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor light emitting device, and more particularly to a semiconductor light emitting device such as a light emitting diode and a semiconductor laser that emits red light from ultraviolet light with high brightness.

Conventionally, how to efficiently extract light emitted from a semiconductor light emitting element as a light source has been a major problem for semiconductor light emitting devices, and various developments have been made.
For example, in a conventional LED light emitting device, an LED is placed on a lead frame having a cup, and the entire LED is sealed with a resin. The sealing resin includes a resin that fills the inside of the cup and a resin that surrounds the entire cup including the resin. The resin filling the inside of the cup contains a fluorescent material that converts or partially absorbs the emission wavelength of the LED, and the emitted light from the LED is wavelength-converted by the fluorescent material. The converted light is scattered in all directions, but most of the converted light is reflected inside the cup and extracted outside.
However, in such a configuration, a part of the light reflected in the cup may become return light, which may be irradiated to the LED and absorbed. Thereby, the characteristic of LED deteriorates, the reduction of output light and the deterioration of a life characteristic are caused. In addition, since the LED and the fluorescent material are in direct contact, the heat generated in the LED propagates to the fluorescent material, which deteriorates the properties of the fluorescent material and also propagates to the sealing resin, deteriorating the sealing resin. There was a problem (see Patent Documents 1 to 3).

Further, in order to obtain a light emitting device having a small light spread angle, it is necessary to reflect as much light emitted from the LED as possible on the inner surface of the cup. Therefore, the area of the LED mounting surface of the cup is made larger than the bottom surface of the LED, the depth of the cup is increased, and light from the side surface of the LED is reflected by a large area of the bottom surface and the inclined surface of the cup.
However, reflecting the emitted light from the side surface of the LED within the cup causes problems such as a reduction in the entire emitted light.

Further, in order to improve the deterioration of the characteristics of the fluorescent material, in the light emitting device in which the LED or semiconductor laser and the fluorescent material are mounted separately, the proportion of the scattered light absorbed by the LED or the semiconductor laser itself increases, and the output light There is also a problem that the reduction of the light emission and the deterioration of the life characteristics become more prominent, resulting in a light emitting device with low light emission efficiency (Patent Documents 4 to 7).
Furthermore, in order to improve the above-described decrease in light emission efficiency, a light emitting device in which an LED and a fluorescent material are separated from each other and a sealing resin is provided on the outer periphery of the fluorescent material has been proposed. Since the resin is in contact with the LED, there is a problem that the resin deteriorates due to heat generation of the LED (Patent Document 6).
JP-A-10-163535 JP 2006-60244 JP-A-2005-194340 JP-A-7-282609 JP 2005-19981 A JP-A-11-87778

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a semiconductor light-emitting device that can efficiently extract emitted light from a semiconductor light-emitting element to the outside.

The semiconductor light emitting device of the present invention is
A semiconductor light emitting device;
A pedestal on which the semiconductor light emitting element is mounted;
A cap through which light from the semiconductor light emitting element passes, and a through hole that becomes a wide opening from a side closer to the semiconductor light emitting element to a side far from the semiconductor light emitting element;
A first translucent member that is at least partially supported in the through hole of the cap and transmits light emitted from the semiconductor light emitting element;
And a second translucent member that is supported at least in part in the through hole of the cap, contains a phosphor, and transmits light from the first translucent member.
In this semiconductor light emitting device, it is preferable that the second light transmissive member has a higher refractive index than the first light transmissive member.
The semiconductor light emitting element is preferably spaced from the cap.
Furthermore, it is preferable that the first light transmitting member has a light incident side surface disposed in the through hole of the cap.
The semiconductor light emitting element is preferably a semiconductor laser or an edge emitting LED.
The second light transmissive member is preferably made of a material having a lower melting point or softening point than the first light transmissive member.
The second translucent member preferably has a curved surface on the light incident side and / or light emitting side.

  According to the semiconductor light emitting device of the present invention, it is possible to re-reflect the light that is reflected by the second light transmissive member and returns to the semiconductor light emitting element side out of the light emitted from the semiconductor light emitting element. It can be taken out efficiently. As a result, a semiconductor light emitting device with high luminous efficiency can be provided.

As shown in FIGS. 1 and 2, the semiconductor light emitting device of the present invention typically has a semiconductor light emitting element (for example, a semiconductor laser, hereinafter simply referred to as “light emitting element”) 11, A base 12 for mounting the light emitting element 11 and a cap 13 that covers the light emitting element 11 together with a part of the base 12 are provided.
The cap 13 has a bottomed cylindrical shape, and a through hole 16 through which light emitted from the light emitting element 11 passes is formed at a substantially central portion of the upper surface. The through hole 16 has a shape that becomes a wide opening from the inside facing the light emitting element to the outside. Further, in the through hole 16, a first light transmissive member that transmits light emitted from the light emitting element and a second light transmissive member that transmits light from the first light transmissive member are provided from the inside. Are arranged in this order.
The pedestal 12 is formed with a through hole 20 for projecting one end of a lead 14 electrically connected to an electrode (not shown) of the light emitting element 11 via a wire 19 in the vertical direction. An insulating material 15 is embedded in the gap between the base 12 and the lead 14 in the through hole 20.

In the semiconductor light emitting device of the present invention, as shown in FIG. 3, a through-hole 26 having a wide opening from the inside toward the outside is formed on the side surface of the cap 23, and the cap 23 is connected to the semiconductor light emitting element 11. A part of the base 22 may be covered.
As shown in FIG. 10, the light 53 a that normally enters the first light transmissive member 17 out of the light emitted from the semiconductor light emitting element is reflected by the second light transmissive member 18, and is thus on the semiconductor light emitting element side. (Light: 53b). However, according to the semiconductor light emitting device of the present invention, it can be re-reflected by the inner surface 17a (light incident side surface) of the first light transmissive member 17 (light: 53c), and the light is efficiently extracted outside. It becomes possible. In addition, since the inner surface of the second light transmissive member is disposed in the through hole having the inclined inner wall, the light reflected by the second light transmissive member is efficiently reflected by the inner wall of the through hole. Can do.

(Semiconductor light emitting device)
As the semiconductor light emitting device, various devices such as a light emitting diode and a semiconductor laser can be used. Since the directivity is high, it is easy to guide light in one direction, and the emitted light can be extracted to the outside with high efficiency. Therefore, a semiconductor laser is preferable.
The semiconductor laser device is not particularly limited, and includes a structure in which an active layer having a multiple or single quantum well structure is sandwiched between an n-type semiconductor layer and a p-type semiconductor layer.
The wavelength of light emitted from the light emitting element is not particularly limited. For example, in the case of blue laser light, the semiconductor layer is preferably formed of a group III nitride semiconductor.

As a semiconductor laser element made of a group III nitride semiconductor, for example, on a conductive or insulating substrate such as sapphire, SiC, ZnO, or GaN, non-doped Al _x Ga _1-x N (0 ≦ x ≦ 1) is used as a base. A nitride semiconductor made of Si, and an n-type contact layer made of Si-doped Al _x Ga _1-x N (0 <x <1), Si-doped In _x Ga _1-x N (0 ≦ x ≦ 1) ) Crack prevention layer (can be omitted), n-type cladding layer having a superlattice structure made of non-doped Al _x Ga _1-x N (0 ≦ x ≦ 1) and Si-doped GaN, and n-type guide layer made of GaN , a multiple quantum well structure having a barrier layer of undoped _{in x Ga 1-x N (} 0 <x <1) well layer and a Si-doped or undoped in _{in x Ga 1-x N (} 0 <x <1) some active layer, Mg-doped _Al x Ga ₁ There _{x N (0 <x <1} ) cap made of layers, p-type guide layer made of Dondopu GaN, the superlattice structure composed of Dondopu _{Al x Ga 1-x N (} 0 ≦ x ≦ 1) and Mg-doped GaN A p-type cladding layer and a p-type contact layer made of Mg-doped GaN are stacked. Further, this semiconductor laser element has two or more reflective films (SiO ₂ , TiO ₂ , ZrO ₂ , AlN, Al ₂ O ₃ , MgF _2, etc.) on the end face (resonator end face) of the optical waveguide.

  In addition, it is preferable that a light emitting element is installed on a base via a heat radiating member, for example with a bonding member. The light-emitting element may be placed on the pedestal in any form such as face-down mounting, face-up mounting, or flip chip structure. Face-down mounting is a method in which the semiconductor layer side of the light emitting element is mounted on a mounting substrate (heat dissipating member). In face-up mounting, the substrate side of the light emitting element is mounted on a mounting base (heat radiating member). Flip chip mounting is a structure in which the surface of a light emitting element and a mounting substrate are connected by conductive protruding terminals (bumps) arranged on an array.

  In the semiconductor light emitting device of the present invention, only one light emitting element may be mounted on one device, or two or more light emitting elements may be mounted. When a plurality of light emitting elements are mounted, their wavelengths may be the same wavelength band or different. In particular, a light emitting element corresponding to RGB is arranged on the same heat radiating member. In this case, it may be arranged in a separated state on the heat radiating member, or two elements may be arranged on one element arranged on the heat radiating member. Alternatively, a two-wavelength integrated arrangement in which the other two elements are formed as one element on one element arranged on the heat dissipation member may be used, or vice versa. Also in the case of such a light emitting element, heat can be effectively radiated.

The heat radiating member plays a role of releasing heat generated in the light emitting element, and preferably has a higher thermal conductivity than the substrate of the light emitting element. Also, the one having a thermal expansion coefficient close to that of the light emitting element, one capable of relieving thermal stress, one whose surface is composed only of an inorganic material, one capable of releasing heat in a predetermined direction (for example, Al ₂ O ₃ , Si, AlN, diamond, Cu-diamond, or the like) is preferable. Those materials having a self-shape holding force are preferable because they can be easily assembled. Specifically, Al ₂ O ₃ , SiC, AlN, Cu, Cu—W, Cu—Mo, Cu—diamond, diamond, Si, or a combination thereof can be given.

  Examples of the bonding member for bonding the light emitting element and the heat dissipation member include an alloy such as Au—Sn, a multilayer structure film such as Ti / Pt / Au, Ti / Pt / Au / Pt, and the like. For bonding, for example, heat sealing is suitable.

  Further, when a light emitting diode is used as the light emitting element, an end face light emitting type is preferable. An edge-emitting diode refers to a diode that emits light from the end face of an active layer, like a semiconductor laser. Such a diode realizes light emission from the end face by increasing the refractive index of the active layer and causing optical waveguide action. By narrowing the output area in this way, it becomes easier to guide the output light from the semiconductor light emitting element into a through hole formed in the cap, which will be described later, and as a result, the light extraction efficiency from the light emitting element can be improved. it can.

(pedestal)
The pedestal is a member for mounting the light emitting element. The shape is not particularly limited, and examples thereof include a plan view, a polygon such as a square and a rectangle, a circle, a semicircle, and an ellipse. The pedestal can be formed of metal such as Cu, Fe, Co, Ni, Au, Al, brass, Kovar, and stainless steel, ceramics such as Al ₂ O ₃ , SiC, and AlN, diamond, and the like. Note that the pedestal has a wall portion erected in the vertical direction or the like in order to mount the light emitting element in an arbitrary direction such as a horizontal direction or a vertical direction according to the light emission form of the light emitting element to be used. Also good.
Such a pedestal does not necessarily have to be composed of one part, and may be composed of a plurality of members or parts. The members or parts can be joined by brazing with Au—Sn or the like, resistance welding, soldering, or the like.
One or two or more through holes or recesses may be formed in order to project the leads and the like from the pedestal. For example, an insulating material or the like may be embedded in the gap between the pedestal and the lead. Examples of the insulating material include ceramics such as ZrO ₂ , Al ₂ O ₃ , AlN, and SiC, resins such as silicone, epoxy, and aromatic polyether ketone, low-melting glass, and combinations thereof.

(cap)
The cap is for covering the light emitting element, and particularly for hermetically sealing the light emitting element mounted on the pedestal. The cap is not particularly limited, but is preferably formed of a material having high thermal conductivity. For example, various materials such as Ni-Fe alloy, Kovar, Ni, Co, Fe, and brass can be used. Usually, the cap is separated from the light emitting element, covers the light emitting element, and is bonded to the base by resistance welding, soldering, or the like. Therefore, it is preferably formed of Fe—Ni alloy, Ni, Kovar or the like that can be resistance-welded using projection. Moreover, in order to prevent deterioration, such as oxidation, a cap may be plated with Ni, Ag, etc., for example.
By disposing the cap away from the light emitting element, it is possible to make it difficult for heat generated in the light emitting element to be transmitted to a second light transmissive member, which will be described later, provided in the cap. Can be limited.
The shape of the cap is not particularly limited, and for example, a bottomed cylindrical shape (such as a cylinder or a polygonal column) or a truncated cone (such as a truncated cone or a polygonal truncated cone), a dome shape, and a deformed shape thereof. Various shapes are mentioned.

（式中、Ａ（ｍｍ^２）はキャップ内側の貫通孔の面積、Ｌ（ｍｍ）は発光素子とキャップまでの距 離、Ｒ（°）は、発光素子からの出射光の広がり角を表す（図９参照））。 The cap has a through-hole through which light from the light emitting element passes in a portion facing the light emitting portion of the light emitting element according to the mounting form of the light emitting element on the base. Therefore, the through hole may be formed in any part such as the upper surface or the side surface of the cap.
The planar shape of the through hole is not particularly limited, and examples thereof include a polygon such as a circle, an ellipse, a rectangle, a square, and a rhombus in a plan view inside or outside the cap. Further, different planar shapes may be used on the inside and outside of the cap. The size of the through hole inside the cap can be appropriately adjusted according to the spread angle of the emitted light of the light emitting element, the distance between the light emitting element and the cap, and the like.
For example, at least inside the cap, it is only necessary to match the outer shape and size of the emitted light of the light emitting element, that is, to allow almost all the emitted light from the light emitting element to enter the through hole. Here, almost all means 80% or more of the entire emitted light. For example, the area of the through hole inside the cap can be set in a range represented by the following formula.

(In the formula, A (mm ² ) is the area of the through hole inside the cap, L (mm) is the distance between the light emitting element and the cap, and R (°) is the spread angle of the light emitted from the light emitting element ( (See FIG. 9)).

Specifically, as shown in FIG. 9, the width of the end face which is the light emitting surface of the light emitting element 11 is about 0.03 to 0.8 mm, the thickness is about 0.01 to 0.8 mm, and the area is 0.0009. ˜0.5 mm ² , further, the spread angle R of the light emitted from the light emitting element is about 10 to 65 °, and the distance L between the light emitting element 11 and the through hole 16 is about 0.02 to 0.8 mm. The diameter a inside the cap of the through hole 16 can be about 0.01 to 0.8 mm, and the cross-sectional area A can be about 0.000076 to 0.5 mm ² .
The through hole has a wide opening from the inner side (side closer to the light emitting element) to the outer side (side far from the light emitting element). That is, the planar shape (cross-sectional area) increases in the direction away from the light emitting element. Accordingly, examples of the shape of the through hole include an inverted truncated cone shape and a cup shape. The degree of spreading of the through hole from the inside to the outside of the cap is not particularly limited. For example, an inclination angle of about 30 to 75 ° (for example, as shown in FIG. α) is preferred. By setting such an inclination angle, light reflected on the inner surface of the second translucent member, which will be described later, can be efficiently reflected by the inner wall of the through hole, thereby improving the light extraction efficiency. be able to.
The through hole supports at least a part of a second light transmissive member, which will be described later, and further transmits light from the semiconductor light emitting element to the light emitting element side of the second light transmissive member. At least a part of the first translucent member is supported. The through hole may not support all of the second light transmissive member within the through hole, and may be disposed so as to protrude to the outside of the cap, for example. Moreover, although all the 1st translucent members may be supported in the through-hole, you may arrange | position so that it may protrude inside a cap, for example.

The cap may further include a reflective member. The reflecting member reflects the light emitted from the light emitting element, the light emitted from the wavelength conversion member, or the light diffused by the light diffusing material. The reflecting member is, for example, a portion where the second light transmitting member is disposed and its periphery, that is, a part or the whole of the inner wall of the through hole, a part or the whole of the base, a part of the inside and / or the outside of the cap. Or it is preferable to arrange | position on the whole surface. By disposing such a reflecting member, the light emitted and / or reflected in an unintended direction can be efficiently extracted to the outside by being re-reflected, and the light extraction efficiency can be improved.
The reflecting member is not particularly limited, and examples thereof include metals such as Ag, Au, Al, Ni, In, Pd, and Ti, In-Ag, Au-Ag, Ag-Bi, Ag-Nd-Cu, Ag-Au-Cu, Ti-Ni-Au-Ag-Al, Ti-Ag-Al, Ti-Ni-Au-Ag, Ni-Au-Ag, Au-Ag-Al, Ti-Ag, Ag-Al, etc. _{alloy, AlN, SiO 2, TiO 2} , Ta 2 O 5, SiO, SiN, ZnO, Al 2 O 3, Ti 3 O 5, Ti 2 O 3, TiO, Nb 2 O 5, CeO 5, ZnS, MgF It can be formed by a single layer film or a laminated film of ₂ or the like or a combination thereof. Although the thickness of the reflecting member is not particularly limited, for example, it is preferably formed along the inner wall of the through hole so as not to block the inside of the through hole.

The reflective member may be covered with a protective film. The protective film functions to suppress the deterioration of the reflecting member, thereby extending the life of the light emitting device. The reflecting member is prevented from coming into contact with the outside, and the chemical reaction and contamination of the reflecting member itself are prevented.
The protective film is preferably formed of a material having a high light transmittance. Thereby, the light reflected by the reflecting member can be efficiently extracted to the outside. _{Specifically, ZnO, SiO, SiO 2,} Al 2 O 3, ITO, MgF 2, Nb 2 O 5, TiO 2, ZrO 2, AlN glass, ceramics _{(ZrO 2, Al 2 O 3} , AlN, GaN , etc. ), Resin (silicone resin, epoxy resin, etc.) or a combination thereof.
The protective film can also contribute to adhesion between the second light transmissive member and the first light transmissive member and the cap. Thereby, the contact | adhesion intensity | strength to the cap of a 2nd translucent member and a 1st translucent member can be improved.
In addition, although the thickness of a protective film is not specifically limited, For example, it is preferable to form so that all the reflection members may be covered so that the inside of a through-hole may not be block | closed.

(Second translucent member)
The second light transmissive member is a member that allows light from the light emitting element to pass therethrough and needs to be substantially transparent. Here, the term “transparent” means that the absorptance of light emitted from the light emitting element is low, in other words, 60% or more, 85% or more, and further 90% or more of the light emitted from the light emitting element can be transmitted. Point to.
Moreover, it is preferable that a 2nd translucent member has a larger refractive index than air | atmosphere and the 1st translucent member mentioned later so that it may mention later.

The second light transmitting member is formed of, for example, glass, quartz glass, sapphire, ceramic (ZrO ₂ , Al ₂ O ₃ , AlN, GaN, etc.), resin (silicone resin, epoxy resin, etc.), or a combination thereof. be able to. Moreover, since the wavelength conversion member may exist in the 2nd light transmission member in the 2nd light transmission member so that it may mention later, the emitted light from a light emitting element irradiates a wavelength conversion member, and wavelength conversion It is more preferable that the material has a low light absorption rate.

The shape of the second translucent member is not particularly limited, and for example, a spherical shape, a hemispherical shape, a lens shape, a disc shape, a conical shape, a truncated cone shape, or a polygonal shape in plan view. Examples include shape. Among them, those having a curved surface on the light incident side and / or light exit side, such as a spherical shape or a hemispherical shape, particularly those having a curved surface on the light incident side, minimize the return light to the light emitting element due to reflection. This is preferable because the light extraction efficiency can be improved. In the case where the second light transmitting member is formed by a curved surface, in order to obtain good orientation characteristics, the second light transmitting member has a portion located at the center of the through hole and / or its periphery at the top. It is preferably located at a point. In addition, although the thickness of the 2nd translucent member is not specifically limited, For example, about 0.001 mm-about 1 mm are illustrated. The thickness of the second light transmissive member is preferably uniform over the entire surface.
The second translucent member heats and dissolves the material constituting the second translucent member so as to cover the first translucent member disposed in the through hole, and controls the amount thereof. It can form by introduce | transducing in a through-hole. Specifically, methods such as fusion by atmospheric heating, heat fusion by a lamp heater, heat fusion by laser light, or fusion by heating a jig can be used.

Further, the second translucent member may have a filter formed on the surface thereof for reducing reflection of light incident from the semiconductor light emitting element. The filter may be either a single layer film or a multilayer film. In particular, when a multilayer film is used, it is preferable to alternately form a high refractive index material and a low refractive index material. _{Specifically, AlN, SiO 2, TiO 2} , Ta 2 O 5, SiO, Al 2 O 3, Ti 3 O 5, Ti 2 O 3, TiO, Nb 2 O 5, CeO 5, ZnS, MgF 2 , etc. Or a combination thereof may be mentioned.

  It is preferable that the 2nd translucent member contains the wavelength conversion member and / or the light-diffusion material. Note that, regardless of whether or not such a material is contained, the second light transmissive member may be formed of a single layer, or may be a multilayer structure of different layers of materials, Furthermore, you may form so that 1 or 2 or more of a wavelength conversion member and / or a light-diffusion material may be contained in a single layer or multiple layers.

  The wavelength conversion member emits light whose wavelength has been converted by being irradiated with light emitted from the light emitting element, and as a result, a color mixture of the light of the light emitting element and the light whose wavelength has been converted by the wavelength conversion member Light can be extracted outside. In other words, light having a desired wavelength can be extracted by selecting a wavelength conversion member as necessary. Only one type of wavelength conversion member may be used, or two or more types may be used in combination. For example, the following method is exemplified as a method for obtaining white light using a wavelength converting substance. In the first method, yellow light-emitting phosphor is excited by blue light emitted from the light-emitting element. Thereby, the yellow light partially converted in wavelength and the blue light not converted are mixed and emitted as white light. In the second method, red, blue and yellow phosphors are excited by ultraviolet light emitted from the light emitting element. The wavelength-converted three-color light is mixed and emitted as white. In the third method, green and red phosphors are excited by blue light emitted from the light emitting element. The wavelength-converted two-color light and the light of the light emitting element are mixed and emitted as white.

  The wavelength conversion member is not particularly limited, but typically, cadmium zinc sulfide activated with copper, YAG phosphor and LAG phosphor activated with cerium, CASN, CASBN, CCA, β Examples thereof include phosphors such as sialon, silicate, CaS, and Sr thiogallate, or combinations thereof. Furthermore, for example, known phosphors exemplified in JP-A-2005-8844 can be used as the wavelength conversion member.

As the light diffusing material, the light emitted from the light emitting element and / or the light emitted from the wavelength conversion member are diffused. Thereby, the light of a light emitting element can be radiated | emitted uniformly, and light with favorable color distribution can be obtained. For example, aluminum nitride, barium titanate, titanium oxide, aluminum oxide, silicon oxide, silicon dioxide, heavy calcium carbonate, light calcium carbonate, silver, silica (fume silica, precipitated silica, etc.), potassium titanate, barium silicate , Glass fiber and the like, and combinations of two or more thereof.
In addition, it is preferable that the maximum value of the cross-sectional area of the 2nd translucent member is larger than the minimum value of the cross-sectional area of a through-hole. As a result, of the light emitted from the light emitting element, a part of the return light reflected on the light emitting element side surface of the second translucent member is re-reflected by the inner wall in the through hole, and efficiently to the outside. It can be taken out.

(First translucent member)
The first translucent member is a member that is mainly supported in the through-hole in the cap, directly transmits the light from the light emitting element, and makes the light incident on the second translucent member disposed behind the first translucent member. It must be transparent. Moreover, although it depends on the material of the second translucent member described above, the one having a melting point or softening point higher than the melting point or softening point of the second translucent member is preferable. By using such a material, as described above, it has sufficient resistance to the formation of the second light transmissive member by fusion, which will be described later, so as to cover the first light transmissive member, It is possible to easily and simply form the second light transmissive member.
Further, the first light transmissive member has a refractive index (n _in ) greater than the refractive index of the atmosphere (refractive index at a wavelength of 400 to 800: about 1), and the refractive index of the second light transmissive member described above ( n _out ) is preferable (ie, 1 <n _in <n _out ). Although the refractive index difference here is not particularly limited, for example, the refractive index of the first light-transmitting member is as follows as long as the refractive index of the second light-transmitting member is about 1.8 to 2.0. It is exemplified that it is about 6 to 1.79 (preferably about 1.6 to 1.7).

Usually, when the light emitted from the light emitting element is directly incident on the above-described second light transmitting member, the light may return to the light emitting element side due to reflection by the interface between the atmosphere and the second light transmitting member, Reduce the light extraction efficiency. On the other hand, the light emitted from the light emitting element first passes through the first light transmissive member and then enters the second light transmissive member. Thereby, reflection of light on the surface of the second light transmissive member can be relaxed by the first light transmissive member. In other words, it is possible to reduce the influence of reflection on the front surface of the second light transmissive member, which occurs when the light emitted from the semiconductor light emitting element directly enters the second light transmissive member. That is, the reflection of the light from the semiconductor light emitting element on the second light transmissive member can be reflected again on the front surface of the first light transmissive member by arranging the first light transmissive member. Further, the light reflected on the surface of the second light transmissive member and returning to the light emitting element side can be rereflected at the interface between the second light transmissive member and the first light transmissive member. As a result, the return light can be reduced, and as a result, the light of the semiconductor light emitting element can be efficiently extracted to the outside, and the light emission efficiency can be improved. This is particularly effective when the relationship between the refractive indexes of the first light transmitting member and the second light transmitting member as described above is provided.
Since the first light transmissive member is disposed on the side close to the light emitting element (particularly when an LD is used), the first light transmissive member may be deformed by heat caused by the emitted light when the melting point is low. Further, the first light transmissive member is usually disposed between two heat sources (light emitting element and phosphor (second light transmissive member containing)). Therefore, it is preferable that the melting point is high. For example, it can be formed of quartz glass, sapphire, ceramics (ZrO ₂ , Al ₂ O ₃ , AlN, GaN, etc.), resin (silicone resin, epoxy resin, etc.), or a combination thereof. Although the thickness of the 1st translucent member is not specifically limited, For example, about 0.001 mm-1 mm are illustrated. This thickness is not necessarily uniform over the entire surface.

The shape of the first translucent member is not particularly limited. For example, the spherical shape, the hemispherical shape, the lens shape, the disc shape, the conical shape, the truncated cone shape, or the polygonal shape of the plan view is processed. Examples include shape. Among them, those having a curved surface on the light incident side and / or light exit side, such as a spherical shape and a hemispherical shape, can reduce the light reflected on the surface and returning to the light emitting element side, or the light extraction efficiency can be reduced. It is preferable to improve. In addition, it is preferable that the 1st translucent member has the lower surface arrange | positioned in the through-hole side rather than the lowest surface (inner surface of a cap) of a through-hole.
The transparent member may contain a light diffusing material as described above.
Moreover, the filter for reducing reflection of the light which injects from a semiconductor light-emitting element may be formed in the surface of the 1st translucent member. The filter may be either a single layer film or a multilayer film. In particular, when a multilayer film is used, it is preferable to alternately form a high refractive index material and a low refractive index material. Specifically, the thing similar to the filter in the 2nd translucent member mentioned above is illustrated.
Embodiments of a semiconductor light emitting device according to the present invention will be described below with reference to the drawings.

Example 1
As shown in FIGS. 1 and 2, the semiconductor light emitting device 10 in this embodiment covers a light emitting element 11, a disk-shaped base 12 for mounting the light emitting element 11, and the light emitting element 11 together with a part of the base 12. And a cap 13 to be configured.
As the light emitting element 11, a semiconductor laser element having a peak wavelength of 445 nm was used.
The cap 13 has a shape in which the upper end of the cylinder is covered with an annular upper surface, and light emitted from the light emitting element 11 passes through the cap 13 at a portion facing the light emitting surface of the light emitting element 11. A circular through hole 16 is formed. The through hole 16 has a shape that becomes a wide opening from the inside facing the light emitting element 11 to the outside. The diameter of the through hole 16 is 200 μm inside the cap 13 and 1000 μm outside, and the inclination angle (α in FIG. 2) of the inner wall of the through hole is 60 °. The distance from the light emitting surface of the light emitting element 11 to the cap 13 (through hole 16) is approximately 250 μm. Moreover, the thickness of the cap 13 is about 0.85 mm, for example.

In this through-hole 16, from the inside, the 1st translucent member 17 which permeate | transmits the emitted light from the light emitting element 11, and the 2nd translucent member 18 which permeate | transmits the light from a 1st translucent member, Are arranged in this order.
The first translucent member 17 is made of sapphire and has a substantially spherical shape with a diameter of about 0.4 mm. The refractive index of the first light transmissive member 17 was 1.76.
The second translucent member 18 is formed of borosilicate glass containing YAG and LAG as phosphors and SiO ₂ as a diffusing material, and has a thickness of about 0 along the spherical surface of the first translucent member 17. The first translucent member 17 is covered by 4 mm. The second light transmissive member 18 is bonded to the inside of the through hole 16 of the cap 13 using low melting point glass. The refractive index of the second light transmissive member 18 was 1.8.

  The pedestal 12 is formed of an alloy of copper and iron, and includes a wall portion 12a erected in a substantially vertical direction corresponding to the form of the light emitting element 11 to be used. The pedestal 12 is electrically connected to an electrode (not shown) of the light-emitting element 11 via a wire 19, and a through hole 12 b for projecting one end of a lead 14 disposed in a direction perpendicular to the pedestal 12. Is formed. In the gap between the base 12 and the lead 14 in the through hole 12b, low-melting glass is embedded as the insulating material 15. The lead 14 can be electrically connected to the external electrode.

The light extraction structure of this semiconductor light emitting device can be formed as follows, for example.
First, a plate made of a desired metal is processed to prepare a cap having the shape described above.
A through hole is formed in the central portion of the upper surface of the cap. The through hole can be formed by, for example, cutting, pressing, injection molding, punching, or the like, and at this time, the shape is controlled to have a wide opening from the inside to the outside.
Also, a spherical first light transmissive member having a diameter larger than the minimum diameter of the through hole, smaller than the maximum diameter, and smaller than the thickness of the upper surface of the cap is prepared.
The glass which comprises the 2nd translucent member containing fluorescent substance as a wavelength conversion member is prepared.
Thereafter, a spherical first light-transmitting member is placed in the through hole of the cap, and a material having a lower melting point than the first light-transmitting member, for example, a low-melting glass is used and melted by heating at 900 ° C. in an atmosphere. The first translucent member is fixed to the cap by wearing.
Subsequently, the second translucent member material is disposed on the surface of the first translucent member in the through hole of the cap, and is fused by holding the surface with a mold by heating at 800 ° C. in an atmosphere. The second light transmissive member is fixed to the first light transmissive member.

  In the semiconductor light emitting device configured as described above, the light emitted from the light emitting element 11 passes through the through hole 16 and then enters the transmissive member 17, and then enters the second light transmissive member 18, and the second The wavelength is converted by the phosphor in the translucent member 18. A highly efficient white color was obtained by mixing the blue color of the body light emitting element with the yellow and green colors obtained from the phosphor.

As a comparative example, as shown in FIG. 11, substantially the same as that of Example 1 except that the through hole 16 of the cap 13 includes only the second light transmissive member 98 containing the phosphor and the diffusing material. A semiconductor light emitting device 30 having the same configuration as that of the semiconductor light emitting device was produced.
Using the semiconductor light emitting device shown in FIG. 2 described above and the semiconductor light emitting device of the comparative example shown in FIG. 11, the light flux when the output of the light emitting element was changed was measured.
The result is shown in FIG.
According to FIG. 12, it was confirmed that in the semiconductor light emitting device (solid line) shown in FIG. 2, the luminous flux was improved by about 36% at the output of 400 nW as compared with the semiconductor light emitting device of the comparative example (dotted line).

As described above, in the semiconductor light emitting device according to the example, the through hole is wide from the inside to the outside of the cap, so that the light emitted from the light emitting element is effectively re-reflected from the return light from the through hole. It becomes possible to make it. As a result, the light extraction efficiency can be increased.
Further, since the first light transmissive member and the second light transmissive member are arranged in order from the side closer to the semiconductor element in the through hole, the second light transmissive light out of the light emitted from the light emitting element. Light that is reflected at the interface between the member and the first light transmissive member and returns to the light emitting element side can be efficiently rereflected at the interface between the first light transmissive member and the atmosphere. As a result, return light can be effectively prevented.
In particular, when the bottom surface of the first light transmissive member (most side different from the light emitting element) is disposed in the through hole, the first light transmissive member and the atmosphere out of the light emitted from the light emitting element. The light that is reflected at the interface and returns to the light emitting element side can also be efficiently reflected by the inner wall of the through hole. Therefore, return light can be prevented more effectively.

  On the other hand, in the semiconductor light emitting device of the comparative example, a part of the light emitted from the light emitting element is reflected at the interface between the second light transmissive member and the atmosphere, and compared with the semiconductor light emitting device of Example 1, Lower the extraction efficiency.

Example 2
As shown in FIG. 4, the semiconductor light emitting device 40 of this embodiment is the same as the embodiment except that a reflecting member 41 made of Ag is provided on a part of the outer surface of the cap 13 from the inner wall of the through hole of the cap 13. This is the same as the semiconductor light emitting device 1 of FIG.
The reflecting member 41 can be formed by, for example, a sputtering method.
By providing the reflecting member 41, light that is reflected on the inner surface of the cap 13 of the second light transmitting member 18 and / or the first light transmitting member 17 and returns to the light emitting element 11 side is transmitted through the through hole. Combined with the degree of inclination of 16, it can be effectively taken out of the cap 13.

Example 3
In the semiconductor light emitting device 50 of this embodiment, as shown in FIG. 5, the reflecting member 51 made of Ag and the protective film 52 made of SiO ₂ are formed on a part of the outer surface of the cap 13 from the inner wall of the through hole of the cap 13. The semiconductor light emitting device is the same as the semiconductor light emitting device of Example 1 except that is provided.
By providing the reflecting member 51, the same effect as in the second embodiment can be obtained, and by providing the protective film 52, it is possible to prevent the reflecting member from being deteriorated.

Example 4
In the semiconductor light emitting device 60 of this embodiment, as shown in FIG. 6, the second light transmissive member 68 is formed in a convex shape from the inside of the through hole of the cap 13 to a part of the outer surface of the cap 13. The semiconductor light emitting device of Example 1 is the same as the semiconductor light emitting device of Example 1.
Thereby, the same effect as Example 1 can be acquired.

Example 5
In the semiconductor light emitting device 70 of this embodiment, as shown in FIG. 7, the first translucent member 27 protrudes downward from a through hole of the cap 13 to a part of the inner surface of the cap 13. Except for being formed, it is the same as the semiconductor light emitting device of Example 1.
Thereby, substantially the same effect as in the first embodiment can be obtained.

Example 6
In the semiconductor light emitting device 80 of this embodiment, as shown in FIG. 8, the first light transmissive member 87 and the second light transmissive member 88 are formed flat in the through hole of the cap 13. This is the same as the semiconductor light emitting device of Example 1.
Thereby, substantially the same effect as in the first embodiment can be obtained.

  The present invention can be optimally used as an endoscope light source, a head ride, an inspection machine light source, a sensor light source, a display backlight, and a light source used for optical communication.

It is an external appearance perspective view of the semiconductor light-emitting device of this invention. It is a schematic longitudinal cross-sectional view of the semiconductor light-emitting device of FIG. It is a schematic longitudinal cross-sectional view of another semiconductor light-emitting device of this invention. It is a schematic longitudinal cross-sectional view which shows the semiconductor light-emitting device of Example 2 of this invention. It is a schematic longitudinal cross-sectional view which shows the semiconductor light-emitting device of Example 3 of this invention. It is a schematic longitudinal cross-sectional view which shows the semiconductor light-emitting device of Example 4 of this invention. It is a schematic longitudinal cross-sectional view which shows the semiconductor light-emitting device of Example 5 of this invention. It is a schematic longitudinal cross-sectional view which shows the semiconductor light-emitting device of Example 6 of this invention. It is a schematic longitudinal cross-sectional view for demonstrating the relationship of the position, shape, etc. of the semiconductor light-emitting element and through-hole of the semiconductor light-emitting device of this invention. It is the schematic of the principal part for demonstrating the course of the light in the semiconductor light-emitting device of this invention. 6 is a longitudinal sectional view of a semiconductor light emitting device in Comparative Example 1. FIG. 12 is a graph showing output-light flux characteristics in the semiconductor light emitting device of FIGS. 2 and 11.

Explanation of symbols

10, 20, 30, 40, 50, 60, 70, 80 Semiconductor light emitting device 11 Light emitting element 12, 22 Base 12a Wall portion 13, 23 Cap 14 Lead 15 Insulator 16, 12b, 26 Through holes 17, 77, 87 First 1 translucent member 17a inner surface 18, 68, 78, 88, 98 second translucent member 19 wire 41, 51 reflective member 52 protective film 53a, 53b, 54c light

Claims (7)

A semiconductor light emitting device;
A pedestal on which the semiconductor light emitting element is mounted;
A cap through which light from the semiconductor light emitting element passes, and a through hole that becomes a wide opening from a side closer to the semiconductor light emitting element to a side far from the semiconductor light emitting element;
A first translucent member that is at least partially supported in the through hole of the cap and transmits light emitted from the semiconductor light emitting element;
A semiconductor light emitting device comprising: a second translucent member that is supported at least in part in the through hole of the cap, contains a phosphor, and transmits light from the first translucent member.   The semiconductor light emitting device according to claim 1, wherein the second light transmissive member has a higher refractive index than the first light transmissive member.   The semiconductor light-emitting device according to claim 1, wherein the semiconductor light-emitting element is separated from the cap.   4. The semiconductor light emitting device according to claim 1, wherein the first light transmitting member has a light incident side surface disposed in a through hole of the cap. 5.   The semiconductor light-emitting device according to claim 1, wherein the semiconductor light-emitting element is a semiconductor laser or an edge-emitting LED.   6. The semiconductor light emitting device according to claim 1, wherein the second light transmissive member is formed of a material having a lower melting point or softening point than the first light transmissive member. The semiconductor light-emitting device according to claim 1, wherein the second light-transmissive member has a curved surface on a light incident side and / or a light-emitting side.

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