KR101777262B1 - A light emitting device - Google Patents

Abstract

The light emitting device includes a substrate, a first conductive semiconductor layer on the substrate, an active layer, and a second conductive semiconductor layer, the light emitting structure exposing a part of the first conductive semiconductor layer, A conductive layer on the contact layer in ohmic contact with the contact layer, a first electrode pad on the exposed first conductive type semiconductor layer, and a second electrode pad on the second conductive type semiconductor layer through the conductive layer and the contact layer, And a second electrode pad that is in Schottky contact with the second electrode pad.

Description

A light emitting device

The present invention relates to a light emitting device and a light emitting device package.

2. Description of the Related Art Generally, a light emitting diode (LED) converts an electric signal into an infrared ray, a visible ray, or a light by using a compound semiconductor characteristic of recombination of electrons and holes. Semiconductor device.

In general, LEDs are used for home appliances, remote controls, display boards, displays, various automation devices, and optical communication. The types of LEDs are divided into IRED (Infrared Emitting Diode) and VLED (Visible Light Emitting Diode).

In the LED, the frequency (or wavelength) of the emitted light is a function of the band gap of the semiconductor material. When a semiconductor material having a small band gap is used, photons of low energy and long wavelength are generated, When a semiconductor material having a bandgap is used, short wavelength photons are generated. Therefore, the semiconductor material of the device is selected depending on the type of light to be emitted.

Embodiments provide a light emitting device, a light emitting device package, and a lighting device capable of improving current dispersion and luminous efficiency.

A light emitting device according to an embodiment includes a substrate, a first conductive semiconductor layer on the substrate, an active layer, and a second conductive semiconductor layer, the light emitting structure exposing a part of the first conductive semiconductor layer, Type semiconductor layer, a conductive layer on the contact layer in ohmic contact with the contact layer, a first electrode pad on the exposed first conductive type semiconductor layer, and a second electrode pad on the conductive layer and the contact layer, And a second electrode pad in Schottky contact with the conductive semiconductor layer.

The second electrode pad may include a body that contacts the upper surface of the conductive layer, and a through hole that branches from the body and penetrates through the conductive layer and the contact layer and has a lower surface in Schottky contact with the second conductive type semiconductor layer. have. The perforations may have different widths. The width of the body may be greater than the width of the penetrating portion. The width of the penetration portion may be 50 to 90% of the width of the body.

The light emitting device according to another embodiment includes a substrate, a first conductivity type semiconductor layer on the substrate, an active layer, and a second conductivity type semiconductor layer, the light emitting structure exposing a part of the first conductivity type semiconductor layer, The contact layer on the second conductive type semiconductor layer having an opening exposing a part of the conductive type semiconductor layer, the second conductive type semiconductor layer exposed by the opening, and the ohmic contact with the contact layer Layer, a first electrode pad on the exposed first conductive type semiconductor layer, and a second electrode pad on a conductive layer portion in Schottky contact with the exposed second conductive type semiconductor layer.

The conductive layer may include a Schottky contact portion in Schottky contact with the second conductive semiconductor layer exposed through the opening and an ohmic contact portion in ohmic contact with the contact layer. The second electrode pad may be disposed on the Schottky contact portion and the ohmic contact portion adjacent thereto. The second electrode pad overlaps at least a portion in a direction perpendicular to the Schottky contact, wherein the vertical direction may be a direction from the substrate to the light emitting structure.

The embodiment can disperse the current and improve the luminous efficiency.

1 is a cross-sectional view of a light emitting device according to a first embodiment.
2 to 6 show a method of manufacturing the light emitting device shown in FIG.
7 is a cross-sectional view of a light emitting device according to the second embodiment.
8 to 12 show a manufacturing method of the light emitting device shown in Fig.
13 shows a light emitting device package according to an embodiment.
14 shows a lighting device including a light emitting device according to an embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. In the drawings, dimensions are exaggerated, omitted, or schematically illustrated for convenience and clarity of illustration. Also, the size of each component does not entirely reflect the actual size. The same reference numerals denote the same elements throughout the description of the drawings. Hereinafter, a light emitting device and a light emitting device package according to embodiments will be described with reference to the accompanying drawings.

1 is a cross-sectional view of a light emitting device 100 according to a first embodiment. Referring to FIG. 1, a light emitting device 100 includes a substrate 110, a light emitting structure 120, a contact layer 130, a conductive layer 140, a first electrode pad 150, Pad 160 as shown in FIG.

The substrate 110 may be selected from the group consisting of a sapphire substrate (Al ₂ O ₃ ), GaN, SiC, ZnO, Si, GaP, InP, Ga ₂ O ₃ , a conductive substrate, and GaAs. An irregular pattern may be formed on the upper surface of the substrate 110. On the substrate 110, a layer or pattern using a compound semiconductor of Group 2 or Group 6 elements is formed on at least one of a ZnO layer (not shown), a buffer layer (not shown) and an undoped semiconductor layer (not shown) . The buffer layer or the undoped semiconductor layer may be formed using a compound semiconductor of a group III-V element, and the buffer layer may reduce the difference in lattice constant with respect to the substrate. The undoped semiconductor layer may be a GaN- .

The light emitting structure 120 includes a first conductive semiconductor layer 122, an active layer 124, and a second conductive semiconductor layer 126. For example, the light emitting structure 120 may include a first conductive semiconductor layer 122, an active layer 124, and a second conductive semiconductor layer 126 sequentially formed on a substrate 110.

The first conductive semiconductor layer 122 may be a nitride semiconductor layer. For example, the first conductive semiconductor layer 122 may be selected from among InAlGaN, GaN, AlGaN, InGaN, AlN, and InN, and may be doped with an n-type dopant such as Si, Ge, or Sn.

The active layer 124 may be formed of a single or multiple quantum well structure, a quantum-wire structure, a quantum dot structure, or the like using a compound semiconductor material of Group 3-V group elements.

For example, the active layer 124 includes a semiconductor material having a composition formula of In _x Al _y Ga _{1 -x- y} N (0? X? 1, 0? _Y? 1, 0? _X + y? 1) A structure including at least one of a quantum wire structure, a quantum dot structure, a single quantum well structure or a multi quantum well (MQW) structure.

The second conductivity type semiconductor layer 126 may be a nitride-based semiconductor layer. For example, it may be selected from InAlGaN, GaN, AlGaN, InGaN, AlN and InN, and may be doped with a p-type dopant such as Mg, Zn, Ca, Sr, Ba and the like.

The second conductive semiconductor layer 126, the active layer 124, and the first conductivity type semiconductor layer 122 are etched to expose a portion of the first conductivity type semiconductor layer 122. The upper surface of the first conductivity type semiconductor layer 122 exposed by the mesa etching may be etched to expose a portion of the first conductive type semiconductor layer 122 at the lower surface of the active layer 124, .

The contact layer 130 is disposed on the second conductivity type semiconductor layer 126. The contact layer 130 is formed of a nitride semiconductor layer such as a semiconductor having a composition formula of In _x Al _y Ga _{1 -x- y} N (0? X? 1, 0? _Y? 1, 0? _X + Layer. For example, the contact layer 130 may be an undoped InAlGaN layer, a p-type InAlGaN layer, or a thin InGaN layer to which no impurity is added, and the thickness thereof may be 30 Å or less. The contact layer 130 may also be an InGaN / GaN superlattice layer, or an AlGaN / GaN superlattice layer.

Since the contact layer 130 can change the lattice constant and the band gap energy independently, contact resistance by ohmic contact can be lowered when the hetero structure is formed. The electric field in the contact layer 130 consists of a piezoelectric polarization field and an electric field by the ionized acceptor in the surface depletion layer. These two electric fields can reduce the tunneling barrier width and improve the tunneling tranport, thereby reducing the contact resistance.

The conductive layer 140 is disposed on the contact layer 130 and the conductive layer 140 is in ohmic contact 165 with the contact layer 130. The conductive layer 140 not only reduces the total reflection but also increases light extraction efficiency of the light emitted from the active layer 124 to the second conductivity type semiconductor layer 126 because of its good translucency.

The conductive layer 140 may include a transparent conductive oxide layer such as indium tin oxide (ITO), tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), indium aluminum zinc oxide (Indium Gallium Zinc Oxide), IGTO (Indium Gallium Tin Oxide), AZO (Aluminum Zinc Oxide), ATO (Antimony Tin Oxide), GZO (Gallium Zinc Oxide), IrOx, RuOx, RuOx / ITO, IrOx / Au, or Ni / IrOx / Au / ITO.

The first electrode pad 150 is disposed on the exposed first conductivity type semiconductor layer 122 and receives a first power from an external power source (not shown). The second electrode pad 160 is disposed on the conductive layer 140 and receives a second power from an external power source (not shown). The first electrode pad 150 and the second electrode pad 160 may be formed of at least one of titanium (Ti), chrome (Cr), nickel (Ni), aluminum (Al), platinum (Pt) .

The second electrode pad 160 penetrates the conductive layer 140 and the contact layer 130 and makes a Schottky contact with the second conductive semiconductor layer 126. The portion of the second electrode pad 160 that contacts the second conductive semiconductor layer 126 includes a Schottky contact portion 161 that is in Schottky contact with the second conductive semiconductor layer 126. At this time, the width of the Schottky contact portion 161 may be 50 to 90% of the width of the second electrode pad 160.

For example, the second electrode pad 160 may include a body 162 that contacts the upper surface of the conductive layer 140, and a second electrode pad 160 that branches off from the body 162 and penetrates the conductive layer 140 and the contact layer 130, And a penetration portion 164 in contact with the conductive type semiconductor layer 162. The lower surface of the penetrating portion 164 is in Schottky contact with the second conductive type semiconductor layer 126 and the side surface of the penetrating portion 164 is in contact with the conductive layer 140 and the penetrated portion of the contact layer 130 have.

As shown in FIG. 1, the body 162 and the penetrating portion 164 may have different widths. For example, the width of the body 162 may be greater than the width of the penetrating portion 164 in schottky contact with the second conductive type semiconductor layer 126. Specifically, the width of the penetrating portion 164 may be 50 to 90% of the width of the body 162.

A current supplied to the second electrode pad 160 flows from the body 162 to the conductive layer 140 and flows from the side surface of the penetrating portion 164 to the conductive layer 140 and the contact layer 130, . However, the flow of current from the second electrode pad 160 to the second conductivity type semiconductor layer 126 through the Schottky contact portion 161 is cut off. The Schottky contact portion 161 serves as a current blocking layer (CBL). That is, the Schottky contact portion 161 disperses the current supplied to the light emitting structure 120 to prevent current from concentrating on one portion of the light emitting structure 120, and can improve the light emitting efficiency of the light emitting device 100 have.

In the first embodiment, a part of the second electrode pad 160 makes a schottky contact with the second conductive type semiconductor layer 126, thereby improving the current dispersion and the luminous efficiency.

2 to 6 show a method of manufacturing the light emitting device shown in FIG. The same components as those in the embodiment shown in Fig. 1 are denoted by the same reference numerals, and redundant description will be omitted.

2, a light emitting structure 120 in which a first conductive semiconductor layer 122, an active layer 124, and a second conductive semiconductor layer 126 are sequentially stacked is formed on a substrate 110 , A contact layer 130 is formed on the light emitting structure 120.

The light emitting structure 120 and the contact layer 130 may be formed by a metal organic chemical vapor deposition (MOCVD) method, a chemical vapor deposition (CVD) method, a plasma enhanced chemical vapor deposition (PCVD) method, , Molecular beam epitaxy (MBE), hydride vapor phase epitaxy (HVPE), and the like.

Referring to FIG. 3, mesa etching is performed on the contact layer 130, the second conductive semiconductor layer 126, the active layer 124, and the first conductive semiconductor layer 122 to form a first conductive Type semiconductor layer 122 is exposed.

Next, referring to FIG. 4, a conductive layer 140 is formed on the contact layer 130. At this time, the conductive layer 140 may make an ohmic contact with the contact layer 130.

Referring to FIG. 5, a conductive layer 140 and a contact layer 130 are etched using photolithography and etching to expose a portion of the second conductive type semiconductor layer 126 1 openings 210 are formed.

Referring to FIG. 6, a first electrode pad 150 is formed on the exposed first conductive semiconductor layer 122. The first opening 210 is filled with at least one of a metal material such as titanium (Ti), chrome (Cr), nickel (Ni), aluminum (Al), platinum (Pt) A second electrode pad 160 having a Schottky contact portion 161 which is in Schottky contact with the conductive semiconductor layer 162 is formed. At this time, the second electrode pad 160 may be formed on the upper surface of the conductive layer 140 adjacent to the first opening 210. The second electrode pad 160 may be the same as that described with reference to FIG. The first electrode pad 150 and the second electrode pad 160 may be formed at the same time.

7 is a cross-sectional view of a light emitting device 200 according to the second embodiment. Referring to FIG. 7, the same parts as those in the embodiment shown in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted.

Referring to FIG. 7, the light emitting device 200 includes a substrate 110, a light emitting structure 120, a contact layer 310, a conductive layer 320, a first electrode pad 150, Pad 330 as shown in FIG.

The light emitting structure 120 has a structure in which a first conductive semiconductor layer 122, an active layer 124, and a second conductive semiconductor layer 126 are stacked on a substrate 110. The first conductive semiconductor layer 122 are exposed.

The contact layer 310 is disposed on the second conductive semiconductor layer 126 and has a second opening 420 exposing a portion of the second conductive semiconductor layer 126.

The conductive layer 320 is disposed on the contact layer 310 and a part of the second conductive semiconductor layer 126 exposed by the second opening 420. The conductive layer 320 is in Schottky contact with the second conductive semiconductor layer 126 exposed through the second opening 420 and in ohmic contact with the contact layer 310. That is, the conductive layer 320 includes a Schottky contact portion 340 which is in Schottky contact with the second conductive type semiconductor layer 126 exposed through the second opening portion 420, and a Schottky contact portion 340 which is in ohmic contact with the contact layer 310 345).

The first electrode pad 150 is disposed on the exposed first conductivity type semiconductor layer 122. The second electrode pad 330 is disposed on the conductive layer 320 that is in Schottky contact with the exposed second conductive semiconductor layer 126. The second electrode pad 330 is disposed on the Schottky contact portion 340 and the conductive layer 320 on the ohmic contact portion 345 adjacent thereto. The second electrode pad 330 overlaps at least part of the Schottky contact portion 340 in the vertical direction. Here, the vertical direction may be a direction from the substrate 110 to the light emitting structure 120.

For example, a portion of the second electrode pad 330 may contact the conductive layer 320 on the Schottky contact portion 340 and the remaining portion may contact the ohmic contact portion 345 adjacent the Schottky contact portion 340 .

The current supplied to the second electrode pad 330 can flow to the first electrode pad 150 through the ohmic contact portion 345 but does not flow to the second electrode pad 330 through the Schottky contact portion 340 . The Schottky contact portion 340 serves to disperse the current supplied to the light emitting structure 120, thereby improving the luminous efficiency of the light emitting device 200.

In the second embodiment, the portion of the conductive layer 320 located under the second electrode pad 330 is in Schottky contact with the second conductive type semiconductor layer 126 to block the current flow, thereby improving the current dispersion and the resulting luminous efficiency Can be improved.

8 to 12 show a manufacturing method of the light emitting device 200 shown in FIG. 8, a light emitting structure 120 in which a first conductive semiconductor layer 122, an active layer 124, and a second conductive semiconductor layer 126 are sequentially stacked is formed on a substrate 110 , A contact layer 310 is formed on the light emitting structure 120.

9, mesa etching is performed on the contact layer 310, the second conductivity type semiconductor layer 126, the active layer 124, and the first conductivity type semiconductor layer 122, Type semiconductor layer 122 is exposed.

Referring to FIG. 10, the contact layer 310 is etched using a photolithography process and an etching process to form a second opening 420 exposing a portion of the second conductive type semiconductor layer 126.

Referring to FIG. 11, a conductive layer 320 (not shown) is formed on the conductive layer 320 so as to be in Schottky contact with a portion of the second conductive type semiconductor layer 126 exposed through the second opening 420 and in ohmic contact with the contact layer 310. [ Is formed on the contact layer 310 having the second opening.

Next, referring to FIG. 12, a first electrode pad 150 is formed on the conductive layer 320. The second electrode pad 330 is formed on the conductive layer 310 that is in Schottky contact with the second conductive semiconductor layer 122 exposed by the second opening 420. For example, the second electrode pad 330 may be formed to contact the Schottky contact portion 340 and the conductive layer 320 on the ohmic contact portion 345 adjacent thereto.

13 shows a light emitting device package according to an embodiment. Referring to FIG. 13, the light emitting device package includes a package body 510, a first metal layer 512, a second metal layer 514, a light emitting device 520, a first wire 522, a second wire 524, Reflective plate 530 and encapsulant layer 540. [

The package body 510 is a structure in which a cavity is formed in one side region. At this time, the side wall of the cavity may be formed to be inclined. The package body 510 may be formed of a substrate having good insulating or thermal conductivity, such as a silicon based wafer level package, a silicon substrate, silicon carbide (SiC), aluminum nitride (AlN) Or may be a structure in which a plurality of substrates are stacked. The embodiments are not limited to the material, structure, and shape of the body described above.

The first metal layer 512 and the second metal layer 514 are disposed on the surface of the package body 510 so as to be electrically separated from each other in consideration of heat discharge or mounting of the light emitting device. The light emitting device 520 is electrically connected to the first metal layer 512 and the second metal layer 514 through the first wire 522 and the second wire 524.

For example, the first wire 522 electrically connects the second electrode pad 160 of the light emitting device 100 or 200 shown in FIG. 1 or 7 to the first metal layer 512, and the second wire 524 The first electrode pad 150 and the second metal layer 514 can be electrically connected to each other.

The reflection plate 530 is formed on the cavity sidewall of the package body 510 to direct the light emitted from the light emitting element 520 in a predetermined direction. The reflection plate 530 is made of a light reflection material, and may be, for example, a metal coating or a metal flake.

The encapsulation layer 540 surrounds the light emitting device 520 located in the cavity of the package body 510 to protect the light emitting device 520 from the external environment. The sealing layer 540 is made of a colorless transparent polymer resin material such as epoxy or silicone. The sealing layer 540 may include a phosphor to change the wavelength of light emitted from the light emitting device 520.

A plurality of light emitting device packages according to the embodiment shown in FIG. 13 are arrayed on a substrate, and a light guide plate, a prism sheet, a diffusion sheet, and the like, which are optical members, may be disposed on a light path of the light emitting device package. The light emitting device package, the substrate, and the optical member may function as a backlight unit.

Still another embodiment may be implemented as a display device, an indicating device, and a lighting system including the 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 streetlight.

14 shows a lighting device including a light emitting device according to an embodiment. 14, the illumination device includes a power coupling 810, a heat sink 820, a light emitting module 830, a reflector 840, and a cover cap 850, And a lens portion 860.

The power coupling unit 810 has a screw shape whose upper end is inserted into an external power socket (not shown) and inserted into an external power socket to supply power to the light emitting module 830. The heat dissipating plate 820 discharges heat generated from the light emitting module 830 through the heat dissipating fin formed on the side surface. The upper end of the heat dissipating plate 820 is screwed to the lower end of the power coupling portion 810.

A light emitting module 840 including light emitting device packages mounted on a circuit board is fixed to a bottom surface of the heat dissipating plate 820. Here, the light emitting device packages may be the light emitting device package according to the embodiment shown in FIG.

The illumination device 800 may further include an insulation sheet 832 and a reflection sheet 834 for electrically protecting the light emitting module under the light emitting module 830. Also, an optical member that performs various optical functions may be disposed on the path of the light irradiated by the light emitting module 840.

The reflecting mirror 840 is coupled to the lower end of the heat dissipating plate 820 in a frustum shape and reflects light emitted from the light emitting module 830. The cover cap 850 has a circular ring shape and is coupled to the lower end of the reflector 140. The lens portion 860 is fitted to the cover cap 850. The lighting device 800 shown in FIG. 14 may be embedded in a ceiling or a wall of a building and used as a downlight.

The features, structures, effects and the like described in the 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 can be combined and modified by other persons 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.

110: substrate 120: light emitting structure
122: first conductivity type semiconductor layer 124: active layer
126: second conductivity type semiconductor layer 130: contact layer
140: conductive layer 150: first electrode pad
160: second electrode pad 161: Schottky contact
162: body 164:
165: ohmic contact 510: package body
512: first metal layer 514: second metal layer
520: light emitting element 522: first wire
524: second wire 530: reflector
540: sealing layer 810: power coupling part
820: heat dissipating plate 830: light emitting module
840: reflector 850: cover cap
860: lens part.

Claims (9)

delete delete delete delete delete Board;
A light emitting structure including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer on the substrate, the light emitting structure exposing a part of the first conductive semiconductor layer;
A contact layer having an opening exposing a part of the second conductivity type semiconductor layer;
A conductive layer in Schottky contact with the second conductive type semiconductor layer exposed by the opening and in ohmic contact with the contact layer;
The first electrode pad on the exposed first conductive type semiconductor layer:
And a second electrode pad on a conductive layer in an area in which the exposed second conductive type semiconductor layer is in Schottky contact with the second electrode type semiconductor layer. 7. The semiconductor device according to claim 6,
A Schottky contact portion in Schottky contact with the second conductive semiconductor layer exposed through the opening; And
And an ohmic contact portion in ohmic contact with the contact layer. 8. The method of claim 7,
Wherein the second electrode pad is disposed on the Schottky contact portion and the ohmic contact portion adjacent thereto. 8. The method of claim 7,
Wherein the second electrode pad at least partially overlaps with the Schottky contact portion in the vertical direction, and the vertical direction is a direction from the substrate to the light emitting structure.

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