TWI449210B - Light emitting device - Google Patents

Description

Light-emitting element

The present invention relates to a light-emitting element, and more particularly to a light-emitting element having a distributed Bragg reflection structure.

At present, the field of application of light-emitting elements (such as light-emitting diodes) has been extensive. For example, in the fields of display devices, communication devices, lighting devices, medical devices, and communication devices, the application of the light-emitting elements can be seen.

Referring to FIG. 1, a conventional light emitting device 10 is shown, which includes a conductive substrate 11, a bonding layer 13, a metal reflective layer 15, a transparent conductive layer 17, and a semiconductor laminate 19. The adhesive layer 13 is located on the conductive substrate 11, the metal reflective layer 15 is on the adhesive layer 13, the transparent conductive layer 17 is on the metal reflective layer 15, and the semiconductor laminate 19 is on the transparent conductive layer 17. The semiconductor stack 19 includes a p-type gallium nitride layer 192 connected to the transparent conductive layer 17, an n-type gallium nitride layer 196 over the p-type gallium nitride layer 192, and a p-type gallium nitride layer 192 and n-type nitrogen. The active layer 194 between the gallium layers 196.

In the light-emitting element 10, the transparent conductive layer 17 directly contacts the p-type gallium nitride layer 192 to achieve an ohmic contact function, and the high transmittance characteristic of the transparent conductive layer 17 allows the metal reflective layer 15 to exhibit a high reflection function.

However, since heat treatment is required in the manufacturing process of the light-emitting element 10, and mutual diffusion between the transparent conductive layer 17 and the metal reflective layer 15 is easily caused during heat treatment, metal is caused in the manufacturing process of the light-emitting element 10. The reflection layer 15 is atomized, which in turn reduces the reflectance of the metal reflective layer 15, so that the luminous efficiency of the light-emitting element 10 is affected.

Therefore, how to prevent the reflectance of the reflective structure of the light-emitting element from being lowered during the manufacturing process to improve the light-emitting efficiency of the light-emitting element is one of the issues that people in the related art pay attention to.

In view of this, the present invention provides a light-emitting element which can improve luminous efficiency.

The invention provides a light-emitting element comprising a conductive substrate, a metal reflective layer, a multilayer film structure having two or more refractive index dissimilar materials alternately stacked, a transparent conductive layer and a semiconductor laminate. The metal reflective layer is disposed on the conductive substrate. The multi-layer film structure of the alternating stack is disposed on the metal reflective layer, and the multi-layer film structure of the above-mentioned alternately stacked has at least one insulating layer, and has at least one via structure through the multi-layer film structure of the alternating stack, and the transparent conductive layer is disposed in the interaction The stacked multilayer film structure is disposed on the transparent conductive layer.

The invention also provides a light-emitting element comprising a conductive substrate, a metal reflective layer, a multilayer film structure having two or more refractive index dissimilar materials alternately stacked, a transparent conductive layer and a semiconductor laminate. The metal reflective layer is disposed on the conductive substrate. The multi-layer film structure of the alternating stack is disposed on the metal reflective layer, and the multi-layer film structure of the above-mentioned alternately stacked is made of a conductive material, and the conductive material includes at least TiO ₂ having doping. The transparent conductive layer is disposed on the multilayer film structure of the alternate stack. The semiconductor stack is disposed on the transparent conductive layer.

The light-emitting element of the present invention adopts a multi-layer film structure which is alternately stacked, and has a multilayer film structure in which two or more kinds of refractive index different materials are alternately stacked to reflect light, and the multi-layer film structure which is alternately stacked can avoid the metal reflective layer and the transparent conductive layer. The problem of mutual diffusion of substances due to thermal action and a decrease in reflectance are beneficial to improve the luminous efficiency of the light-emitting element.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

2 is a schematic view of a light emitting device according to an embodiment of the present invention. Referring to FIG. 2, a light-emitting element 30 according to an embodiment of the present invention includes a conductive substrate 31, a metal reflective layer 33, a multilayer film structure 35 having two or more refractive index dissimilar materials, and a transparent conductive layer 37, A semiconductor stack 39, a via structure 352, and an electrode 41.

As shown in FIG. 2, the light-emitting element 30 is a vertical light-emitting diode; wherein the metal reflective layer 33 is located on the conductive substrate 31, and the stacked multilayer film structure 35 is located on the metal reflective layer 33, and the transparent conductive layer 37 is located. The stacked multilayer multilayer film structure 35 is disposed on the transparent conductive layer 37. Further, the electrode 41 is disposed on the semiconductor laminate 39. Wherein, the above-mentioned stacked multilayer film structure 35 has at least one insulating layer, wherein the insulating layer material may be Ta ₂ O ₅ , SiN _x , TiO ₂ or SiO ₂ , and the above-mentioned alternately stacked multilayer film structure 35 has at least A via structure 352 is penetrated therethrough, and the via structure 352 is used to form an electrical connection between the metal reflective layer 33 and the transparent conductive layer 37. In the embodiment of FIG. 2, although only one via structure 352 is illustrated, the present invention is not limited to the number of via structures 352. In other embodiments, the number of via structures 352 may be plural. Moreover, the material of the above-mentioned via structure 352 is filled with a high-light reflective metal or a thermo-stable metal material, and a high-light reflective metal such as silver, aluminum, gold, or an alloy thereof is used, thereby improving the light-emitting element 30. The light reflectivity, and the thermally stable metal material may be a metal such as titanium, aluminum, or chromium or an alloy of the above metals to improve the compactness of the via structure 352.

In addition, the interaction of the stacked multilayer film structure 35 also may be a stack of an insulating material different from the interaction, the aforementioned insulating material may be _{Ta 2 O 5, SiN x,} TiO 2 or SiO _2; in the present embodiment, stacked one The multilayer film structure 35 is formed by alternately stacking two insulating materials of TiO ₂ and SiO ₂ .

According to the above, the so-called multi-layer film structure 35 having two or more refractive index dissimilar materials alternately stacked is generally formed by stacking two materials having different refractive indexes. In this embodiment, the stack is alternately stacked. The multilayer film structure 35 is a Distributed Bragg Reflector (DBR) structure in which the thickness of each layer is λ/4, where λ is the dominant wavelength of the light-emitting element 30.

Furthermore, the material of the semiconductor stack 39 may be selected from an aluminum indium gallium nitride series material or an aluminum indium gallium phosphide series material, and may include a first conductive type semiconductor layer 392, an active layer 394, and a second conductive type semiconductor layer 396. . The first conductive semiconductor layer 392 is located on the transparent conductive layer 37, the active layer 394 is located on the first conductive semiconductor layer 392, and the second conductive semiconductor layer 396 is disposed on the active layer 394.

In detail, the active layer 394 may be a multi-quantum well (MQW) structure, and the first conductive semiconductor layer 392 and the second conductive semiconductor layer 396 may be a p-type semiconductor layer and an n-type semiconductor layer, respectively. . In more detail, the first conductive semiconductor layer 392 and the second conductive semiconductor layer 396 may be a p-type gallium nitride layer and an n-type gallium nitride layer, respectively.

Moreover, the surface of the semiconductor stack 39 may be a roughened structure to reduce the occurrence of total reflection after the light is generated by the active layer due to the difference in refractive index between the semiconductor layer 39 and the outside, thereby increasing the light-emitting element 30. Light extraction efficiency.

In addition, the material of the transparent conductive layer 37 may be a transparent metal oxide material such as ITO, CTO, ZnO, In ₂ O ₃ , SnO ₂ , CuAlO ₂ , CuGaO ₂ , SrCu ₂ O ₂ , in this embodiment, a transparent conductive layer The material of 37 is ITO.

Moreover, the material of the conductive substrate 31 may be zinc oxide, tantalum or metal. Further, a back electrode 312 may be formed on the lower surface of the conductive substrate 31.

In addition, the metal reflective layer 33 described above may have the function of a bonding layer for bonding the conductive substrate 31 and the multilayer film structure 35 which are alternately stacked. In the present embodiment, the metal reflective layer 33 may be selected from a metal having high light reflectivity such as silver, aluminum, gold, and alloys thereof, and formed by a metal eutectic bonding technique such that the metal reflective layer 33 is formed. At the same time, it has the function of bonding layer. It should be noted, however, that the present invention is not limited to the fact that the metal reflective layer 33 has a bonding effect at the same time.

FIG. 3 shows another embodiment of the present invention. As shown in FIG. 3, the metal reflective layer 33 and the conductive substrate 31 further have a bonding layer 34, and the bonding layer 34 mainly functions to improve the metal reflective layer 33 and the conductive substrate 31. For the bonding force, the material of the bonding layer 34 may be a metal material or an organic material having conductive particles.

In summary, the light-emitting element of the present invention uses a multilayer film structure in which two or more refractive index dissimilar materials are alternately stacked to separate the metal reflective layer from the transparent conductive layer to reduce the between the metal reflective layer and the transparent conductive layer. The problem of atomization of the metal reflective layer due to the thermal diffusion problem, thereby improving the luminous efficiency of the light-emitting element.

Since the multi-layer film structure 35 of the alternating stack is interposed between the metal reflective layer 33 and the transparent conductive layer 37, the interface between the metal reflective layer 33 and the transparent conductive layer 37 does not exist due to mutual diffusion caused by heat, thereby causing metal reflection. The problem of atomization of the layer 33 makes it possible to prevent the reflectance of the metal reflective layer 33 from being affected, thereby contributing to an improvement in the luminous efficiency of the light-emitting element 30. Furthermore, the omnidirectional mirror is formed by the interactively stacked multilayer film structure 35 and the metal reflective layer 33, thereby facilitating the structural design of the light-emitting element 30.

4 is a light emitting device 50 according to another embodiment of the present invention. The light-emitting element 50 is similar to the light-emitting element 30, except that the multi-layer film structure 55 which is alternately stacked is made of a conductive material, and the material thereof may be selected from the group consisting of ITO, CTO, ZnO, In ₂ O ₃ , SnO ₂ , CuAlO _{2 .} , CuGaO ₂ or SrCu ₂ O ₂ . Since the interactively stacked multilayer film structure 55 is made of a conductive material, the metal reflective layer 33 and the transparent conductive layer 37 can be electrically connected directly by the multilayer film structure 55 which is alternately stacked.

In this embodiment, the alternately stacked multilayer film structure 55 comprises at least a material having doped TiO ₂ , wherein the dopant of the TiO ₂ may be a VB group element of the periodic table; in this embodiment, The doped TiO ₂ material may be Ti _x Ta _1-x O ₂ or Ti _x Nb _1-x O ₂ ; further, the multi-layer film structure 55 alternately stacked in this embodiment is Ti _x Ta _{1- x} O ₂ is stacked with ITO.

In addition, the light-emitting element 50 may also include at least one via structure (not shown) extending through the multi-layered film structure 55 for alternately stacking to improve the electrical connection between the metal reflective layer 33 and the transparent conductive layer 37, and the above The material of the via structure is filled with a high-light reflective metal or a thermo-stable metal material, and a high-light reflective metal such as silver, aluminum, gold, or an alloy thereof is used, thereby improving the light reflectance of the light-emitting element 50, The thermally stable metal material may be a metal such as titanium, aluminum or chromium or an alloy of the above metals to improve the compactness of the via structure.

FIG. 5 shows a further embodiment of the present invention. As shown in FIG. 5, the metal reflective layer 33 and the conductive substrate 31 further have a bonding layer 54. The function of the bonding layer 54 is mainly to improve the relationship between the metal reflective layer 33 and the conductive substrate 31. The bonding force, the material of the bonding layer 54 may be a metal material or an organic material having conductive particles.

In summary, the light-emitting element of the present invention uses a multilayer film structure in which two or more refractive index dissimilar materials are alternately stacked to separate the metal reflective layer from the transparent conductive layer to reduce the between the metal reflective layer and the transparent conductive layer. The problem of atomization of the metal reflective layer due to the thermal diffusion problem can prevent the reflectance of the metal reflective layer 33 from being affected, thereby improving the luminous efficiency of the light-emitting element. Furthermore, the multi-layer film structure of the interactive stacking is combined with the metal reflective layer to form an omnidirectional mirror, thereby also facilitating the structural design of the light-emitting element.

While the present invention has been described in its preferred embodiments, the present invention is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

30, 50. . . Light-emitting element

31. . . Conductive substrate

312. . . Back electrode

33. . . Metal reflective layer

34, 54. . . Bonding layer

35, 55. . . Interactively stacked multilayer film structure

352. . . Guide hole structure

37. . . Transparent conductive layer

39. . . Semiconductor stack

392. . . First conductive semiconductor layer

394. . . Active layer

396. . . Second conductive semiconductor layer

41. . . electrode

FIG. 1 is a schematic view of a conventional light-emitting element.

2 is a schematic view of a light emitting device according to an embodiment of the present invention.

3 is a schematic view of a light emitting device according to another embodiment of the present invention.

4 is a schematic view of a light emitting device according to still another embodiment of the present invention.

FIG. 5 is a schematic diagram of a light emitting device according to still another embodiment of the present invention.

30. . . Light-emitting element

31. . . Conductive substrate

312. . . Back electrode

33. . . Metal reflective layer

35. . . Interactively stacked multilayer film structure

352. . . Guide hole structure

37. . . Transparent conductive layer

39. . . Semiconductor stack

392. . . First conductive semiconductor layer

394. . . Active layer

396. . . Second conductive semiconductor layer

41. . . electrode

Claims (20)

A light-emitting element comprising: a metal reflective layer; a multilayer film structure comprising an insulating layer or a metal oxide material on the metal reflective layer; a transparent conductive layer comprising a transparent metal oxide material on the multilayer film structure; a semiconductor stack on the transparent conductive layer; and a via structure between the metal reflective layer and the transparent conductive layer and extending through the multilayer film structure. The light-emitting element of claim 1, wherein the alternately stacked multilayer film structure comprises one or more metal oxide materials. The light-emitting element of claim 1, wherein the multilayer film structure is a dispersed Bragg reflection structure. The light-emitting element of claim 1, wherein the metal reflective layer is a bonding layer. The light-emitting element of claim 1, further comprising a bonding layer connecting the reflective layer, and the bonding layer comprises a metal or an organic adhesive substance having conductive particles. The photovoltaic element according to claim 1, wherein the transparent metal oxide material comprises a group VB element of the periodic table. The illuminating device of claim 1, wherein the semiconductor laminate comprises: a first conductive semiconductor layer connected to the transparent conductive layer; an active layer on the first conductive semiconductor layer; A second conductive semiconductor layer is disposed on the active layer. The light-emitting element of claim 7, wherein the active layer is a multiple quantum well structure. The light-emitting element according to claim 1, wherein the semiconductor laminate comprises an aluminum indium gallium nitride series material or an aluminum indium gallium phosphide series material. The light-emitting element of claim 1, wherein the via structure comprises silver, gold, titanium, aluminum, chromium or an alloy thereof. A light-emitting element comprising: a metal reflective layer; a multilayer film structure comprising an insulating layer or a metal oxide material on the metal reflective layer; and a transparent conductive layer comprising a transparent metal oxide material on the multilayer film structure; a semiconductor stack on the transparent conductive layer; and a via structure extending through the multilayer film structure and not including the metal oxide material. The illuminating element according to claim 11, wherein the The material of the film structure comprises one or more metal oxide materials. The light-emitting element of claim 11, wherein the multilayer film structure is a distributed Bragg reflection structure. The light-emitting element of claim 11, wherein the metal reflective layer is a bonding layer. The light-emitting element according to claim 11, further comprising a bonding layer connecting the reflective layer, and the bonding layer comprises a metal or an organic adhesive substance having conductive particles. The illuminating device of claim 11, wherein the semiconductor laminate comprises: a first conductive semiconductor layer connected to the transparent conductive layer; an active layer on the first conductive semiconductor layer, and A second conductive semiconductor layer is disposed on the active layer. The light-emitting element of claim 16, wherein the active layer is a multiple quantum well structure. The light-emitting element according to claim 11, wherein the semiconductor laminate comprises an aluminum indium gallium nitride series material or an aluminum indium gallium phosphide series material. The light-emitting element of claim 11, wherein the via structure comprises gold, silver, titanium, aluminum, chromium or an alloy thereof. The light-emitting element according to claim 11, wherein the transparent metal oxide material comprises a group VB element of the periodic table.