TWI398023B - A light-emitting device having a patterned surface - Google Patents

Description

Light-emitting element with patterned surface

The present invention relates to a light-emitting element having a patterned surface.

In recent years, the light-emitting diode components have been dedicated to the improvement of brightness, and the final application can be applied to the field of lighting to achieve energy-saving and carbon-saving effects. The improvement of brightness is mainly divided into two parts. One is the improvement of Internal Quantum Efficiency (IQE), which is mainly to improve the bonding efficiency of electron holes through the improvement of epitaxial quality; on the other hand, the light extraction efficiency (Light Extraction) Efficiency; LEE) is mainly focused on making the light emitted by the illuminating layer penetrate effectively to the outside of the component, reducing the absorption of light by the internal structure of the illuminating diode.

Surface roughening technology is considered one of the ways to effectively increase brightness. FIG. 7 illustrates a conventional light-emitting diode 700 having a surface pattern substrate, including a growth substrate 701, an epitaxial laminate, a first electrode 707, and a second electrode 708. The surface 701a of the growth substrate 701 has a plurality of trapezoidal recess patterns to enhance light extraction efficiency. The epitaxial layer stack includes a buffer layer 702 grown on the growth substrate 701, an undoped semiconductor layer 703 grown on the buffer layer 702, and a first doped first semiconductor layer 704 grown on the undoped semiconductor layer. On the 703, an active layer 705 is grown on the first semiconductor layer 704, and a second doped second semiconductor layer 706 is grown on the active layer 705. The first electrode 707 is formed on the exposed first semiconductor layer 704; the second electrode 708 is formed on the second semiconductor layer 706. Due to the pattern design of the general substrate surface 701a, the pattern width and the pattern are designed. The ratio of the interval between the cases is about 1, so that most of the surface area is parallel to the surface 705a of the active layer, and the light emitted from the active layer 705 to the area is easily returned to the epitaxial stack by total reflection, and is The absorption is converted to heat, resulting in poor light extraction efficiency and heat dissipation problems. In addition, in order to compensate for the light loss caused by the parallel regions, the pattern depth is generally deepened to improve the light extraction efficiency of the patterned substrate, but thus a patterned surface having a high aspect ratio is formed, resulting in subsequent epitaxial growth. Difficulties affect the epitaxial quality of the component.

In addition, a conventional surface roughening technique is to form a randomly distributed rough surface on the surface of the substrate by mechanical grinding. This method cannot effectively control the roughening size, for example, depth or width. Moreover, the surface is grown on a messy surface. The epitaxial layer is liable to cause poor quality of the epitaxial layer.

The invention provides a light-emitting element with a patterned surface, which can balance the epitaxial quality and the light extraction effect.

An aspect of the invention discloses a light-emitting element comprising a substrate; an intermediate layer formed on the substrate; a first doped semiconductor layer formed on the intermediate layer, having a first dopant; a second doped semiconductor layer is formed on the first doped semiconductor layer and has a second doping; an active layer is interposed between the first doped semiconductor layer and the second doping Between the semiconductor layers, having an active layer surface; and a patterned surface having a plurality of regularly arranged unit patterns; wherein the corresponding areas of the patterned surface and the surface of the active layer are substantially non-parallel to each other .

Another aspect of the invention discloses a light emitting device comprising a substrate; An intermediate layer is formed on the substrate; a first doped semiconductor layer is formed on the intermediate layer and has a first doping; and a second doped semiconductor layer is formed on the first doped a second doping material on the hetero semiconductor layer; an active layer interposed between the first doped semiconductor layer and the second doped semiconductor layer, having an active layer surface; and a pattern The surface has a plurality of regularly arranged unit patterns; wherein the plurality of regularly arranged unit patterns are closely arranged such that each of the plurality of unit patterns and the adjacent unit patterns are in contact with each other.

1 shows a light-emitting device 100 according to the present invention, comprising a growth substrate 101, an intermediate layer comprising a lattice buffer layer 102 and/or an undoped semiconductor layer 103 epitaxially formed on the growth substrate 101, The first doped first contact layer 104 is epitaxially formed on the undoped semiconductor layer 103, and a first doped layer 105 having a first doping layer is epitaxially formed on the first contact layer 104, an active layer 106 epitaxially formed on the first tie layer 105, a second tie layer 107 having a second dopant is epitaxially formed on the active layer 106, and a second contact layer 108 having a second dopant is epitaxially formed. On the second tie layer 107, a current dispersion layer 109 is formed on the second contact layer 108, and forms a good ohmic contact with the second contact layer 108, and a first electrode 110 is evaporated or sputtered to form a bare electrode. A contact layer 104 and a second electrode 111 are formed by vapor deposition or sputtering on the current dispersion layer 109. The growth substrate 101 has a patterned surface 101a, and the patterned surface 101a includes a plurality of periodically arranged unit patterns. The plurality of periodically arranged unit patterns are arranged closely, for example, a plurality of unit patterns and phases. The adjacent unit patterns are in contact with each other. In this embodiment The patterned surface 101a of any portion, as shown, for example, in the A1 region, is substantially non-parallel to the portion of the corresponding active layer upper surface 106a, such as the A2 region. The plurality of periodically arranged unit patterns are arranged in a fixed period, or may be arranged in a variable period or a quasi-period. The top view of the plurality of unit patterns includes a polygon, for example, a group of at least one pattern selected from the group consisting of a triangle, a quadrangle, and a hexagon. The cross-sectional pattern of the plurality of unit patterns includes at least one pattern selected from the group consisting of a V shape, a semicircle, an arc, and a polygon. In one embodiment, the cross-sectional pattern of the plurality of unit patterns has a width and a depth, wherein the depth is less than the width, so that the subsequently grown lattice buffer layer 102 and/or the undoped semiconductor layer 103 are easily filled into the patterned surface. The recessed area of 101a.

2 shows a light-emitting element 200 according to the present invention. Compared with the light-emitting element 100 of FIG. 1, the cross-sectional pattern of the patterned surface 101b of the light-emitting element 200 has a plurality of periodically arranged unit patterns, and each unit pattern has a circle. The cross-sectional curve of the arc can further assist the subsequent lattice buffer layer 102 and the non-doped semiconductor layer 103 to be filled in the recessed region of the patterned surface 101b. The method for forming a profile curve of a circular arc can form a photoresist mask layer on a surface of a planar substrate, and then pattern the photoresist mask layer by a lithography process, and then place it in a baking device at a suitable temperature. Under baking, the photoresist is reflowed to form a mask layer having a cross-sectional pattern of a circular arc curve, and then wet etching or dry etching is applied to transfer the photoresist pattern to the substrate 101 to form a pattern as shown in FIG. The patterned surface 101b of the arc profile curve. The top view of the plurality of unit patterns includes a polygon, for example, a group of at least one selected from the group consisting of a triangle, a quadrangle, and a hexagon.

Figure 3 discloses a light-emitting element 300 in accordance with the present invention, and Figure 2 Compared with the light-emitting element 200, the patterned surface 101c of the light-emitting element 300 has a unit pattern of different sizes or different patterns for periodic arrangement, and the upper view shape includes different polygons, for example, the different patterns are selected from triangles, A group of quadrilaterals and hexagons.

4 shows a light-emitting element 400 according to the present invention. Compared with the light-emitting element 200 of FIG. 2, the upper surface 108a of the second contact layer 108 of the light-emitting element 400 also has a patterned surface as disclosed in the above embodiment. To further increase the light extraction efficiency, any portion of the second contact layer 108 upper surface 108a and the corresponding active layer upper surface 106a are substantially non-parallel to each other. The upper surface 108a of the second contact layer 108 is formed by adjusting the epitaxial parameters, such as lowering the growth temperature or adjusting the hydrogen/nitrogen concentration ratio in the reactor, when the second contact layer 108 is epitaxially grown. In a manner, the hexagonal pyramidal recess is naturally grown; after the second contact layer 108 is formed, the patterned surface 108a having protrusions and/or depressions is formed by a conventional lithography process. Subsequent current spreading layer 109 is conformally formed on patterned relief surface 108a and forms a good ohmic contact.

Fig. 5 shows a light-emitting element 500 according to the present invention. Compared with the light-emitting element 200 of Fig. 2, the intermediate layer 502 of the light-emitting element 500 is a bonding layer, such as a transparent adhesive layer or a transparent oxide layer. And bonding technology, such as direct bonding or thermocompression bonding, to connect the first contact layer 104 and a second substrate 501. According to the spirit of the embodiment, the second substrate 501 is not limited to a material for growing the epitaxial layer, and the desired material can be selected according to the purpose, such as a material with high thermal conductivity, a transparent material with high transmittance, and a conductive material. Or a material with light reflection.

6A to 6D are the patterned surfaces described in the above embodiments Above view. As shown in FIG. 6A, the above-mentioned patterned surface is composed of hexagonal unit patterns, and each unit pattern is composed of six concave or convex inner surfaces 601a protruding from the surface of the substrate, and the inner inclined surfaces are common. Connected to a center point 601c, and each unit pattern is adjacent to each other to six adjacent sides 601b such that the patterned surface does not substantially have a surface parallel to the corresponding active layer upper surface 106a. As shown in FIG. 6B, the patterned surface may also be composed of a triangular unit pattern, and each unit pattern is composed of three concave or convex inner surfaces 602a protruding from the surface of the substrate, and the inner inclined surfaces are connected together. At a center point 602c, and the unit patterns are connected to each other at three adjacent sides 602b such that the patterned surface does not substantially have a surface parallel to the corresponding active layer upper surface 106a. As shown in FIG. 6C, the patterned surface may also be composed of a diamond-shaped unit pattern, and each unit pattern is composed of four concave or convex inner inclined surfaces 603a, and the inner inclined surfaces are commonly connected to a center. Point 603c, and the unit patterns are connected to each other at four adjacent sides 603b such that the patterned surface does not substantially have a surface parallel to the corresponding active layer upper surface 106a. As shown in FIG. 6D, the above-mentioned patterned surface may also be composed of a square unit pattern defined by overlapping circles, and each unit pattern is composed of four convex outer inclined surfaces 604a and one circular arc top surface 604c. The unit patterns are connected to each other at four adjacent sides 604b such that the patterned surface does not substantially have a surface parallel to the corresponding active layer upper surface 106a. In the above embodiments, the “patterned surface does not substantially have a surface parallel to the surface of the corresponding active layer”, and variations or etchings of the photoresist pattern caused by process variations such as lithography are not excluded herein. Graphical variations, etc., causing some of the patterned areas to still have parallel surfaces or portions of the area that are not graphically flat The surface of the row, such as the center point 601c, 602c, 603c or the dome surface 604c, may still form a small platform within the range of process variation, but the process variation is within a controllable range, resulting in parallel surfaces and unpatterned surfaces Its total area does not exceed 3% of the total substrate surface. As shown in FIG. 6E, the patterned surface may also be composed of a circular unit pattern, and each of the unit patterns is a concave or convex arc surface or a hemispherical surface, and each unit pattern is connected to each other. Tightly arranged such that the ratio of the portion of the patterned surface parallel to the upper surface 106a of the corresponding active layer to the patterned surface is approximately the value obtained by subtracting three sector areas from the triangular area in the figure divided by the area of the triangle. It is 9.3%, or no more than 10%.

The unit pattern disclosed in the above embodiments is capable of relatively increasing the epitaxial growth difficulty of the lattice buffer layer and the non-doped semiconductor layer of the subsequent growth due to a large degree of patterning ratio. Considering the light extraction efficiency and the internal quantum efficiency, the cross-sectional pattern of the unit pattern has a width and a depth, wherein the depth is smaller than the width, or a ratio of depth/width thereof is less than 1, to form a unit pattern having a low aspect ratio, so that The subsequently grown lattice buffer layer and/or the undoped semiconductor layer are easily filled into the recessed regions of the patterned surface to enhance the quality of epitaxial growth.

The patterned surface disclosed in the above embodiments is not limited to forming a patterned surface on a specific structure, that is, a patterned surface conforming to the present invention formed on any of the structures is within the scope of the present invention, for example The patterned surface may also be a light-emitting element in contact with one of the light-emitting surface or the environment contact surface; in one embodiment, the material adjacent to the patterned surface includes, but is not limited to, a light-emitting element. Any structure, The encapsulating material or the environmental medium has a different refractive index, and preferably has a refractive index difference of at least 0.1 or more.

In the above embodiments, the material of the lattice buffer layer, the undoped first contact layer, the first tie layer, the second tie layer, the second contact layer, and the active layer comprises a III-V group. a compound such as Al _p Ga _q In _(1-pq) P or Al _x In _y Ga _(1-xy) N, wherein, 0 p, q 1; p, q, x, y are positive numbers; (p+q) 1; (x+y) 1. The first dopant is an n-type dopant, such as Si, or a p-type dopant, such as Mg or Zn; and the second dopant has a conductivity different from that of the first dopant. Type of doping. The current dispersion layer comprises a metal conductive oxide, such as indium tin oxide (ITO), or a semiconductor layer having good conductivity, such as a phosphide or nitride having a high doping concentration. The growth substrate comprises at least one transparent material selected from the group consisting of gallium phosphide, sapphire, tantalum carbide, gallium nitride, and aluminum nitride. The second substrate comprises a transparent material selected from the group consisting of gallium phosphide, sapphire, tantalum carbide, gallium nitride, and aluminum nitride; or the heat conductive material is selected from the group consisting of diamond and diamond-like carbon (DLC). A group of metal materials such as zinc oxide, gold, silver, and aluminum.

The examples of the invention are intended to be illustrative only and not to limit the scope of the invention. Any changes or modifications of the present invention to those skilled in the art will be made without departing from the spirit and scope of the invention.

100, 200, 300, 400, 500‧‧‧Lighting elements

101‧‧‧ Growth substrate

101a, 101b, 101c, 101d‧‧‧ graphical surface

102‧‧‧ lattice buffer layer

103‧‧‧Undoped semiconductor layer

104‧‧‧First contact layer

105‧‧‧First tie layer

106‧‧‧Active layer

106a‧‧‧ Upper surface of the active layer

107‧‧‧Second tie layer

108‧‧‧Second contact layer

108a‧‧‧Second contact layer upper surface

109‧‧‧current conduction layer

110‧‧‧First electrode

111‧‧‧second electrode

112‧‧‧Transparent adhesive layer

501‧‧‧second substrate

502‧‧‧Intermediate

601a, 602a, 603a, 604a‧‧‧ inner slope

601b, 602b, 603b, 604b‧‧‧ adjacent

601c, 602c, 603c‧‧‧ center point

604c‧‧‧Dome face

1 is a schematic view showing a first embodiment of a light-emitting element according to the present invention; FIG. 2 is a schematic view showing a second embodiment of a light-emitting element according to the present invention; and FIG. 3 is a schematic view showing light-emitting according to the present invention. a third embodiment of the component; FIG. 4 is a schematic view showing a fourth embodiment of the light-emitting component according to the present invention; 5 is a schematic view showing a fifth embodiment of a light-emitting element according to the present invention; FIGS. 6A to 6E are schematic views showing a top view of a patterned substrate according to the present invention; and FIG. 7 is a schematic view showing a front view The structure of the light-emitting elements of the art.

100‧‧‧Lighting elements

101‧‧‧ Growth substrate

101a‧‧‧Graphic surface

102‧‧‧ lattice buffer layer

103‧‧‧Undoped epitaxial layer

104‧‧‧First contact layer

105‧‧‧First tie layer

106‧‧‧Active layer

106a‧‧‧ Upper surface of the active layer

107‧‧‧Second tie layer

108‧‧‧Second contact layer

109‧‧‧current conduction layer

110‧‧‧First electrode

111‧‧‧second electrode

Claims (21)

A light-emitting element comprising: a substrate having a patterned surface, the patterned surface having a plurality of unit patterns; an intermediate layer formed on the substrate; a first doped semiconductor layer formed on the intermediate layer, having a first doped material; a second doped semiconductor layer formed on the first doped semiconductor layer, having a second doping; and an active layer interposed between the first doped semiconductor layer and the second doped Between the hetero-semiconductor layers, having a gluten layer surface; wherein the patterned surface of any portion is substantially non-parallel to the corresponding surface portion of the active layer; and wherein the intermediate layer comprises at least one crystal a buffer layer, an undoped semiconductor layer or a bonding layer. The light-emitting element of claim 1, wherein the plurality of unit patterns are arranged in a fixed period, a variable period, or a quasi-period. The illuminating element of claim 1, wherein the plurality of unit patterns comprise a polygon in a top view. The illuminating element of claim 3, wherein the plurality of unit patterns have a top view comprising at least one graphic selected from the group consisting of A group of triangles, squares, and hexagons. The light-emitting element of claim 1, wherein the cross-sectional pattern of the plurality of unit patterns comprises at least one pattern selected from the group consisting of a V shape, a semicircle, an arc shape, and a polygon. The light-emitting element according to claim 1, wherein the cross-sectional pattern of at least one of the plurality of unit patterns has a width and a depth smaller than the width. The illuminating element of claim 1, wherein the cross-sectional pattern of the plurality of unit patterns comprises at least two arcs of different curvatures. The light-emitting element of claim 1, wherein the surface of the active layer is substantially a plane. The light-emitting element of claim 1, wherein the outer surface of the second doped semiconductor layer has a porous hole structure. A light-emitting element comprising: a substrate having a patterned surface, the patterned surface having a plurality of unit patterns; an intermediate layer formed on the substrate; a first doped semiconductor layer formed on the intermediate layer, having a first doping; a second doped semiconductor layer formed on the first doped semiconductor layer, having a second dopant; An active layer is interposed between the first doped semiconductor layer and the second doped semiconductor layer, and has an active layer surface; wherein the plurality of unit patterns are arranged in a tightest arrangement such that each of the plurality of unit patterns and phases The adjacent unit patterns are in contact with each other; and wherein the intermediate layer includes at least one lattice buffer layer, an undoped semiconductor layer or a bonding layer. The illuminating element according to claim 10, wherein the patterned surface of any one of the portions is substantially non-parallel to the corresponding surface portion of the active layer. The light-emitting element of claim 10, wherein the plurality of unit patterns are arranged in a fixed period, a variable period, or a quasi-period. The illuminating element of claim 10, wherein the plurality of unit patterns comprise a polygon in a top view. The light-emitting element of claim 13, wherein the plurality of unit patterns have an at least one pattern selected from the group consisting of a triangle, a quadrangle, and a hexagon. The light-emitting element according to claim 10, wherein the cross-sectional pattern of the plurality of unit patterns comprises at least one pattern selected from the group consisting of a V shape, a semicircle, an arc shape, and a polygon. The illuminating element according to claim 10, wherein the complex The cross-sectional pattern of at least one of the plurality of unit patterns has a width and a depth less than the width. The illuminating element of claim 10, wherein the cross-sectional pattern of the plurality of unit patterns comprises at least two arcs of different curvatures. The light-emitting element according to claim 10, wherein the surface of the active layer is a flat surface. The light-emitting element according to claim 10, wherein the outer surface of the second doped semiconductor layer has a porous hole structure. The light-emitting element according to claim 10, wherein the plurality of unit patterns have a circular shape in a top view. The illuminating element of claim 20, wherein the patterned surface is parallel to the patterned surface of the corresponding surface portion of the active layer by no more than ten percent.