KR20120037709A - Light emitting device - Google Patents

Abstract

PURPOSE: A light emitting device is provided to improve light extraction efficiency by reducing damage in a growth process of a conductive semiconductor layer. CONSTITUTION: A light emitting structure(150) is formed on a nitride semiconductor layer(140) and includes a first conductive semiconductor layer(152), an active layer(154), and a second conductive semiconductor layer(156). An ohmic layer(162) is formed on the light emitting structure. A reflection layer(164) is formed on the ohmic layer. A conductive support substrate(168) is formed on the reflection layer.

Description

Light emitting device

The embodiment relates to a light emitting device and a method of manufacturing the same.

A light emitting device such as a light emitting diode or a laser diode using a group 3-5 or 2-6 compound semiconductor material of a semiconductor can realize various colors such as red, green, blue, and ultraviolet rays by developing thin film growth technology and device materials. Efficient white light can be realized by using fluorescent materials or combining colors.

With the development of these technologies, LED backlights, fluorescent lamps or incandescent bulbs, which replace not only display elements but also cold cathode fluorescent lamps (CCFLs), which form the backlight of optical communication means, transmission modules, and liquid crystal display (LCD) displays. Applications are expanding to white light emitting diode lighting devices, automotive headlights and traffic lights that can be substituted for them.

Here, in the structure of the LED, since the P electrode, the active layer, and the N electrode are sequentially stacked on the substrate, and the substrate and the N electrode are wire bonded, currents may be energized with each other.

At this time, when a current is applied to the substrate, since current is supplied to the P electrode and the N electrode, holes (+) are emitted from the P electrode to the active layer, and electrons (-) are emitted from the N electrode to the active layer. Therefore, as holes and electrons combine in the active layer, energy corresponding to the band gap energy of the active layer is emitted in the form of light.

The light emitting device according to the embodiment is intended to improve the light extraction efficiency of the light emitting device by reducing damage in the growth process of the conductive semiconductor layer.

Embodiments may include a light emitting structure including a second conductive semiconductor layer, an active layer, and a first conductive semiconductor layer; And a nitride semiconductor layer doped with europium (Eu) on the first conductive semiconductor layer.

Another embodiment includes forming a first nitride semiconductor layer on a substrate; Etching the first nitride semiconductor layer to form irregularities on a surface thereof; Flatly forming a second nitride semiconductor layer doped with europium on the unevenness of the first nitride semiconductor layer; Forming a light emitting structure on the second nitride semiconductor layer, the light emitting structure including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; And it provides a method of manufacturing a light emitting device comprising the step of removing the substrate and the first nitride semiconductor layer.

The bandgap energy of the nitride semiconductor layer doped with europium may be smaller than the bandgap energy of the first conductive semiconductor layer.

The nitride semiconductor layer may be a gallium nitride layer.

In addition, the nitride semiconductor may have irregularities formed on at least one surface thereof.

In addition, the unevenness may include a conical shape.

The light emitting device may further include a conductive support substrate on the first surface of the light emitting structure, and a first electrode formed on a second surface of the light emitting structure that faces the first surface of the light emitting structure.

In the light emitting device according to the embodiment, damage is reduced in the growth process of the conductive semiconductor layer, thereby improving light extraction efficiency of the light emitting device.

1A to 1H are views showing a first embodiment of a light emitting device,
2A to 2H are views showing a second embodiment of the light emitting device,
3A to 3I are views showing a third embodiment of the light emitting device.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In the description of the above embodiments, each layer (region), region, pattern or structures may be "on" or "under" the substrate, each layer (layer), region, pad or pattern. In the case of what is described as being formed, "on" and "under" include both being formed "directly" or "indirectly" through another layer. In addition, the criteria for the top or bottom of each layer will be described with reference to the drawings.

In the drawings, the thickness or size of each layer is exaggerated, omitted, or schematically illustrated for convenience and clarity of description. In addition, the size of each component does not necessarily reflect the actual size.

1A to 1H are diagrams illustrating a first embodiment of the light emitting device. 1A to 1H illustrate a first embodiment of a light emitting device.

First, as shown in FIG. 1A, the buffer layer 110 and the undoped semiconductor layer 120 are grown on the substrate 100.

The substrate 100 may include a conductive substrate or an insulating substrate, for example, at least one of sapphire (Al ₂ O ₃ ), SiC, Si, GaAs, GaN, ZnO, Si, GaP, InP, Ge, and Ga ₂ 0 ₃ . Can be used. An uneven structure may be formed on the substrate 100, but is not limited thereto. Impurities on the surface may be removed by wet cleaning the substrate 100.

In addition, the buffer layer 110 may be grown between the light emitting structure and the substrate 100 to be described later in order to alleviate the difference in lattice mismatch and thermal expansion coefficient of the material. The material of the buffer layer 110 may be formed of at least one of Group III-V compound semiconductors such as AlN, for example, GaN, InN, InGaN, AlGaN, InAlGaN, and AlInN.

An undoped semiconductor layer 120 may be formed on the buffer layer 110, for example, an AlGaN layer may be grown.

Subsequently, as illustrated in FIG. 1B, the undoped semiconductor layer 120 is etched. In this case, the undoped semiconductor layer 120 is etched by using a wet etching process or a dry etch process. A mask 130 may be provided on the undoped semiconductor layer 120 for an etching process.

In the etching process, the mask 130 may be made of oxide-based materials such as SiO ₂ , TiO _2, and ITO, various metallic materials such as Cr, Ti, Al, Au, Ni, Pt, and Photo Resist (PR). .

Dry etching includes physical methods by ion bombardment, chemical methods by reactants generated in plasma, and the like, and may be performed using, for example, inductively coupled plasma (ICP) or reactive ion etchant (RIE) equipment. .

A portion 120a of the undoped semiconductor layer 120 is removed in the etching process, and as a result, the undoped semiconductor layer 120 has an uneven shape. In this case, the irregularities may form a predetermined pattern or may be irregularly formed.

As shown in FIG. 1C, the nitride semiconductor layer 140 is grown on the undoped semiconductor layer 120 having the unevenness. Europium may be doped into the nitride semiconductor layer 140. In this case, the nitride semiconductor layer 140 may be formed to fill the irregularities on the undoped semiconductor layer 120 and flat. In addition, the nitride semiconductor layer 140 doped with europium may have a bandgap energy smaller than that of the undoped semiconductor layer 120.

As shown in FIG. 1D, the light emitting structure 150 includes a first conductive semiconductor layer 152, an active layer 154, and a second conductive semiconductor layer 156 on the nitride semiconductor layer 140. Can be formed. The light emitting structure 150 may be grown by vapor deposition such as metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), and hydraulic vapor phase epitaxy (HVPE).

The first conductivity type semiconductor layer 152 may be implemented as a group III-V compound semiconductor doped with a first conductivity type dopant, and when the first conductivity type semiconductor layer 112 is an N-type semiconductor layer, The first conductive dopant may be an N-type dopant and may include Si, Ge, Sn, Se, or Te, but is not limited thereto.

The first conductive semiconductor layer 152 may include a semiconductor material having a composition formula of Al _x In _y Ga _(1-xy) N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1). It may include. The first conductive semiconductor layer 112 may be formed of any one or more of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN, AlGaAs, InGaAs, AlInGaAs, GaP, AlGaP, InGaP, AlInGaP, InP. have.

The first conductive semiconductor layer 152 may form an N-type GaN layer using a chemical vapor deposition method (CVD), molecular beam epitaxy (MBE), or sputtering or hydroxide vapor phase epitaxy (HVPE). . In addition, the first conductive semiconductor layer 112 may include a silane containing n-type impurities such as trimethyl gallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and silicon (Si). The gas SiH ₄ may be injected and formed.

The active layer 154 has an energy band inherent in the active layer (light emitting layer) material because electrons injected through the first conductive semiconductor layer 152 and holes injected through the second conductive semiconductor layer 156 formed thereafter meet each other. It is a layer that emits light with energy determined by.

The active layer 154 may be formed of at least one of a single quantum well structure, a multi quantum well structure (MQW), a quantum-wire structure, or a quantum dot structure. For example, the active layer 114 may be formed by injecting trimethyl gallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and trimethyl indium gas (TMIn) to form a multi-quantum well structure. It is not limited to this.

The well layer / barrier layer of the active layer 154 may have a pair structure of at least one of InGaN / GaN, InGaN / InGaN, GaN / AlGaN, InAlGaN / GaN, GaAs (InGaAs) / AlGaAs, GaP (InGaP) / AlGaP. But it is not limited thereto. The well layer may be formed of a material having a band gap energy lower than the band gap energy of the barrier layer.

A conductive cladding layer (not shown) may be formed on or under the active layer 154. The conductive cladding layer may be formed of an AlGaN-based semiconductor, and may have a higher bandgap energy than the bandgap energy of the active layer 154.

The second conductive type semiconductor layer 156 is a second conductive type dopant is doped III-V compound semiconductor, for example _{-5, In x Al y Ga 1 -x-} y N (0≤x≤1, 0≤y≤ And 1, 0 ≦ x + y ≦ 1). When the second conductive semiconductor layer 116 is a P-type semiconductor layer, the second conductive dopant may include Mg, Zn, Ca, Sr, Ba, or the like as a P-type dopant.

The second conductivity type semiconductor layer 156 is a bicetyl cyclone containing p-type impurities such as trimethyl gallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and magnesium (Mg) in the chamber. Pentadienyl magnesium (EtCp ₂ Mg) {Mg (C ₂ H ₅ C ₅ H ₄ ) ₂ } may be injected to form a p-type GaN layer, but is not limited thereto.

In the present exemplary embodiment, the first conductivity type semiconductor layer 152 may be a P type semiconductor layer, and the second conductivity type semiconductor layer 156 may be an N type semiconductor layer. In addition, an N-type semiconductor layer (not shown) is formed on the second conductive semiconductor layer 156 when a semiconductor having a polarity opposite to that of the second conductive semiconductor layer, for example, the second conductive semiconductor layer is a P-type semiconductor layer. can do. Accordingly, the light emitting structure 150 may be implemented as any one of an N-P junction structure, a P-N junction structure, an N-P-N junction structure, and a P-N-P junction structure.

As illustrated in FIG. 1E, an ohmic layer 162 may be formed on the light emitting structure 150. The ohmic layer 162 may include indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), indium aluminum zinc oxide (IZAZO), indium gallium zinc oxide (IGZO), and indium gallium tin (IGTO). oxide), AZO (aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zinc oxide), IZON (IZO Nitride), AGZO (Al-Ga ZnO), IGZO (In-Ga ZnO), ZnO, IrOx, RuOx, NiO, RuOx / ITO, Ni / IrOx / Au, and Ni / IrOx / Au / ITO, Ag, Ni, Cr, Ti, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, Hf It may be formed to include at least one of, and is not limited to these materials.

And, as shown, a reflective layer 164 may be formed on the ohmic layer 162, the reflective layer 164 is a metal layer containing aluminum (Al), silver (Ag) or an alloy containing Al or Ag. Can be made. Aluminum or silver may effectively reflect light generated from the active layer 154 to greatly improve light extraction efficiency of the light emitting device.

1F, a conductive support substrate 168 may be formed on the reflective layer 164. The conductive support substrate 168 may be copper (Cu), gold (Au), copper alloy (Cu Alloy), nickel (Ni-nickel), copper-tungsten (Cu-W), carrier wafers (eg, GaN, Si, Ge, GaAs, ZnO, SiGe, SiC, SiGe, Ga ₂ O _3, etc.) may be optionally included. The conductive support substrate 168 may be formed using an electrochemical metal deposition method or a bonding method using a eutectic metal.

Here, in order to bond the reflective layer 164 and the conductive support substrate 168, the reflective layer 164 functions as a bonding layer, or using nickel (Ni), gold (Au), or the like. A bonding layer (not shown) may be formed.

Subsequently, as illustrated in FIG. 1G, the substrate 100 and the like are removed. The substrate 100 may be removed by a laser lift off (LLO) method using an excimer laser or the like.

For example, a laser lift-off method focuses a laser light having an energy between a band gap energy of the nitride semiconductor layer doped with a flow path product toward the substrate 100 and a band gap energy of the undoped semiconductor layer. In this case, thermal energy is concentrated at the interface between the undoped semiconductor layer 120 and the nitride semiconductor layer 140, and the interface is separated into gallium and nitrogen molecules, and the undoped semiconductor layer 120 is instantaneously at a portion where the laser light passes. Separation occurs. At this time, by doping the europium to the nitride semiconductor layer 140, the band gap energy can be adjusted to facilitate separation at a desired interface. The bandgap energy of the nitride semiconductor layer 140 doped with a flow path product may be less than the bandgap energy of the first conductive semiconductor layer and the undoped semiconductor layer.

As shown in FIG. 1H, when the first electrode 180 is formed on the nitride semiconductor layer 140, the light emitting device is completed.

The light emitting device according to the present embodiment separates the nitride semiconductor layer 140 on the first conductivity-type semiconductor layer 152 from the substrate 100 by using a laser lift-off method or the like, wherein the nitride semiconductor layer 140 is removed. Unevenness is formed on the surface according to the unevenness of the undoped semiconductor layer 120. Therefore, irregularities having a desired shape and depth may be easily formed on the nitride semiconductor layer 140.

In addition, since irregularities may be formed on the surface of the nitride semiconductor layer 140 before growth of the light emitting structure, damage that may be received by the light emitting structure may be removed in the etching process after the growth of the light emitting structure.

2A to 2H are views showing a second embodiment of the light emitting device.

The present embodiment is basically similar to the first embodiment described above, but the irregularities of the surface of the nitride semiconductor layer 140 are different. That is, when the mask 130 is placed on the surface of the undoped semiconductor layer 120 in the process illustrated in FIG. 2B, the surface of the undoped semiconductor layer 120 is etched into a cone shape 120b.

Therefore, in the process illustrated in FIG. 2C, the nitride semiconductor layer 140 is grown on the undoped semiconductor layer 120. Accordingly, the light emitting device according to the present embodiment is illustrated in FIG. 2G, and conical irregularities are formed on the surface of the nitride semiconductor layer 140 after the separation process.

3A to 3I are views showing a third embodiment of the light emitting device.

This embodiment is basically similar to the first embodiment described above, but the process of forming irregularities on the nitride semiconductor layer 140 is different.

First, as shown in FIG. 3A, the buffer layer 110 and the undoped semiconductor layer 120 are grown on the substrate 100, and details thereof are as described with reference to FIG. 1A.

Subsequently, as illustrated in FIG. 3B, a patterned oxide layer 125 is formed on the undoped semiconductor layer 120. In this case, the pattern of the oxide layer 125 may be formed using the mask 135, and may be formed differently according to the pattern of the surface of the nitride semiconductor layer 140 which will be described later. In this case, the mask 135 used may be made of oxide-based materials such as SiO ₂ , TiO _2, and ITO, various metallic materials such as Cr, Ti, Al, Au, Ni, Pt, and Photo Resist (PR).

As illustrated in FIG. 3C, the nitride semiconductor layer 140 is grown on the undoped semiconductor layer 120 having the oxide layer 125 formed thereon. Europium may be doped into the nitride semiconductor layer 140. In this case, a surface of the nitride semiconductor layer 140 may fill the oxide layer 125 and have irregularities or patterns.

As shown in FIG. 3D, the light emitting structure 150 includes a first conductive semiconductor layer 152, an active layer 154, and a second conductive semiconductor layer 156 on the nitride semiconductor layer 140. It can be formed, the specific method is as described in Figure 1d.

As shown in FIG. 3E, the ohmic layer 162 and the reflective layer 164 may be formed on the light emitting structure 150. A detailed method is the same as described with reference to FIG. 1E.

In addition, as illustrated in FIG. 3F, the conductive support substrate 168 may be formed on the reflective layer 164, which is described in detail with reference to FIG. 1F.

Then, the substrate 100 and the like are removed as shown in FIG. 3G. This process is also the same as that shown in FIG. 1G, but when the oxide layer 125 is removed from the surface of the separated nitride semiconductor layer 140, the pattern is formed on the surface of the nitride semiconductor layer 140 as shown in FIG. 3H. To irregularities are formed.

As shown in FIG. 3H, when the first electrode 180 is formed on the nitride semiconductor layer 140, the light emitting device is completed. In the present exemplary embodiment, patterns or irregularities may be formed on the surface of the nitride semiconductor layer 140 using the patterned oxide layer 125 without etching the surface of the undoped semiconductor layer 120.

4 is a cross-sectional view of an embodiment of a light emitting device package. Hereinafter, an embodiment of the light emitting device package will be described with reference to FIG. 4.

As illustrated, the light emitting device package according to the embodiment may include a package body 320, a first electrode layer 311 and a second electrode layer 312 installed on the package body 320, and the package body 320. The light emitting device 300 includes a light emitting device 300 according to an exemplary embodiment and is electrically connected to the first electrode layer 311 and the second electrode layer 312, and a filler 340 surrounding the light emitting device 300.

The package body 320 may include a silicon material, a synthetic resin material, or a metal material. An inclined surface may be formed around the light emitting device 300 to increase light extraction efficiency.

The first electrode layer 311 and the second electrode layer 312 are electrically separated from each other, and provide power to the light emitting device 300. In addition, the first electrode layer 311 and the second electrode layer 312 can increase the light efficiency by reflecting the light generated from the light emitting device 300, the outside of the heat generated from the light emitting device 300 May also act as a drain.

The light emitting device 300 may be installed on the package body 320 or on the first electrode layer 311 or the second electrode layer 312.

The light emitting device 300 may be electrically connected to the first electrode layer 311 and the second electrode layer 312 by any one of a wire method, a flip chip method, or a die bonding method.

The filler 340 may surround and protect the light emitting device 300. In addition, the filler 340 may include a phosphor to change the wavelength of light emitted from the light emitting device 300.

The light emitting device package may mount at least one of the light emitting devices of the above-described embodiments as one or more, but is not limited thereto.

A plurality of light emitting device packages according to the embodiment may be arranged on a substrate, and a light guide plate, a prism sheet, a diffusion sheet, or the like, which is an optical member, may be disposed on an optical path of the light emitting device package. The light emitting device package, the substrate, and the optical member may function as a light unit. Another embodiment may be implemented as a display device, an indicator device, or a lighting system including the semiconductor light emitting device or the light emitting device package described in the above embodiments, for example, the lighting system may include a lamp and a street lamp. .

Features, structures, effects, and the like described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified with respect to other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

In addition, the above description has been made with reference to the embodiment, which is merely an example, and is not intended to limit the present invention. Those skilled in the art to which the present invention pertains will be illustrated as above without departing from the essential characteristics of the present embodiment. It will be appreciated that various modifications and applications are possible. For example, each component specifically shown in the embodiment can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

100 substrate 110 buffer layer
120: undoped semiconductor layer 130, 135: mask
140: nitride semiconductor layer 150: light emitting structure
152: first conductive semiconductor layer 154: active layer
156: second conductive semiconductor layer 162: ohmic layer
164: reflective layer 168: conductive support substrate
180: first electrode

Claims (7)

A light emitting structure including a second conductive semiconductor layer, an active layer, and a first conductive semiconductor layer; And
A light emitting device comprising a nitride semiconductor layer doped with europium (Eu) on the first conductive semiconductor layer. The method of claim 1,
The band gap energy of the europium-doped nitride semiconductor layer is less than the band gap energy of the first conductive semiconductor layer. The method of claim 1,
The nitride semiconductor layer is a gallium nitride layer. The method of claim 1,
The nitride semiconductor is a light emitting device formed with irregularities on at least one side. The method of claim 4, wherein
The unevenness is a light emitting device comprising a conical shape. The method of claim 1,
And a first electrode formed on the first surface of the light emitting structure and a first electrode formed on a second surface of the light emitting structure opposite to the first surface of the light emitting structure. Forming a first nitride semiconductor layer on the substrate;
Etching the first nitride semiconductor layer to form irregularities on a surface thereof;
Flatly forming a second nitride semiconductor layer doped with europium on the unevenness of the first nitride semiconductor layer;
Forming a light emitting structure on the second nitride semiconductor layer, the light emitting structure including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; And
Removing the substrate and the first nitride semiconductor layer.

Images