Light emitting device and manufacturing method thereof

Provided is a light emitting device. The light emitting device comprises a second electrode layer, a second conduction type semiconductor layer, an active layer, a first conduction type semiconductor layer, a first electrode layer, and an insulating layer. The second conduction type semiconductor layer is formed on the second electrode layer. The active layer is formed on the second conduction type semiconductor layer. The first conduction type semiconductor layer is formed on the active layer. The first electrode layer is formed on the first conduction type semiconductor layer. The insulating layer is disposed between the second electrode layer and the second conduction type semiconductor layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119(e) of Korean Patent Application No. 10-2007-0073253 (filed on Jul. 23, 2007), which is hereby incorporated by reference in its entirety.

BACKGROUND

The present disclosure relates to a light emitting device and a manufacturing method thereof.

A light emitting diode (LED) is widely used as a light emitting device.

The LED includes an N-type semiconductor layer, an active layer, and a P-type semiconductor layer stacked therein. Light is generated from the active layer and emitted to the outside when power is applied.

SUMMARY

Embodiments provide a light emitting device and a manufacturing method thereof.

Embodiments also provide a light emitting device with an improved electrical insulation characteristic, and a manufacturing method thereof.

In an embodiment, a light emitting device comprises: a second electrode layer; a second conduction type semiconductor layer on the second electrode layer; an active layer on the second conduction type semiconductor layer; a first conduction type semiconductor layer on the active layer; a first electrode layer on the first conduction type semiconductor layer; and an insulating layer between the second electrode layer and the second conduction type semiconductor layer.

In an embodiment, a method for manufacturing a light emitting device comprises: forming a first conduction type semiconductor layer, an active layer, and a second conduction type semiconductor layer; forming an insulating layer on a peripheral portion on the second conduction type semiconductor layer; forming a second electrode layer on the second conduction type semiconductor layer and the insulating layer; and forming a first electrode layer on the first conduction type semiconductor layer.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a light emitting device and a manufacturing method thereof according to embodiments are described in detail with reference to the accompanying drawings.

In the following description, it will be understood that when a layer (or film) is referred to as being ‘on’ another layer or substrate, it can be directly on the another layer or substrate, or intervening layers may also be present. Further, it will be understood that when a layer is referred to as being ‘under’ another layer, it can be directly under the another layer, and one or more intervening layers may also be present. In addition, it will also be understood that when a layer is referred to as being ‘between’ two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. Also, ‘on’ and ‘under’ of each layer is judged using the drawings as a reference.

Hereinafter, a light emitting device and a manufacturing method thereof according to embodiments are described in detail with reference to the accompanying drawings.

FIG. 1is a cross-sectional view explaining a light emitting device according to a first embodiment.

Referring toFIG. 1, a light emitting device includes: a second electrode layer40; a second conduction type semiconductor layer16on the second electrode layer40; an active layer15on the second conduction type semiconductor layer16; a first conduction type semiconductor layer14on the active layer15; and a first electrode layer22on the first conduction type semiconductor layer14.

Also, the second electrode layer40may include a metal layer21, a reflective layer20formed on the metal layer21, and an ohmic contact layer19formed on the reflective layer20.

The metal layer21can be formed of at least one of Ti, Cr, Ni, Al, Pt, Au, W, and a conductive substrate. The reflective layer20can be formed of metal including at lease one of Ag, Al, Cu, and Ni having high light reflectivity. The ohmic contact layer19can be a transparent electrode layer, and for example, can be formed of at least one of indium tin oxide (ITO), ZnO, RuOx, TiOx, and IrOx.

Also, an insulating layer18is formed between the second electrode layer40and the second conduction type semiconductor layer16along the lateral surface of the light emitting device. The insulating layer18contacts the upper surface and the lateral surface of the second electrode layer40, and contacts the lower surface of the second conduction type semiconductor layer16. The insulating layer18can be a nitride layer in the group III having a thickness of 0.5-10 μm. For example, the insulating layer18can be an AlxGa1-xN layer (0<x≦1).

The central portion of the metal layer21protrudes to the direction in which the second conduction type semiconductor layer16is disposed. The central portions of the reflective layer20and the ohmic contact layer19also protrude to the direction in which the second conduction type semiconductor layer16is disposed.

Therefore, portions of the metal layer21and the reflective layer20are disposed on the same horizontal plane, and portions of the metal layer21and the ohmic contact layer19are disposed on the same horizontal plane.

Also, portions of the metal layer21and the insulating layer18can be disposed on the same horizontal plane. Portions of the metal layer21, the reflective layer20, the ohmic contact layer19, and the insulating layer18can be disposed on the same horizontal plane.

The upper surface of the first conduction type semiconductor layer14is not formed to have a uniform height but has an uneven surface including convex portions and concave portions.

In the light emitting device according to the first embodiment, the insulating layer18is formed between the second conduction type semiconductor layer16and the second electrode layer40, so that the first conduction type semiconductor layer14or the first electrode layer22is spaced further from the second electrode layer40.

Therefore, short-circuit between the first conduction type semiconductor layer14or the first electrode layer22and the second electrode layer40by an external foreign substance can be prevented.

That is, since the second conduction type semiconductor layer16is formed to have a very thin thickness, short-circuit between the first conduction type semiconductor layer14and the second electrode layer40, or between the first electrode layer22and the second electrode layer40may occur. The light emitting device according to the first embodiment can prevent the short-circuit through the insulating layer18.

Particularly, in the light emitting device according to the first embodiment, the insulating layer18can be a nitride layer and the nitride layer can be formed with a thick thickness, so that short-circuit is effectively prevented.

FIGS. 2 to 6are views explaining a method for manufacturing a light emitting device according to the first embodiment.

Referring toFIG. 2, a substrate11, a buffer layer12, an un-doped GaN layer13, a first conduction type semiconductor layer14, an active layer15, and a second conduction type semiconductor layer16are sequentially formed.

Also, a mask layer17is formed on positions spaced from peripheral portions on the second conduction type semiconductor layer16. For example, the mask layer17can be formed of SiO2or SiN.

Referring toFIG. 3, an insulating layer18is deposited on the second conduction type semiconductor layer16on which the mask layer17is formed.

The insulating layer18can be a nitride layer in the group III. For example, the insulating layer18can be an AlxGa1-xN layer (0<x≦1).

At this point, the insulating layer18does not grow at the central portion where the mask layer17is formed, but grows on only the peripheral portions of the second conduction type semiconductor layer16where the mask layer17is not formed.

The insulating layer18can be grown by flowing tri methyl gallium (TMGa) gas and tri methyl aluminum (TMAl) gas together with a hydrogen gas and an ammonia gas into a chamber at temperature of 600-1200° C.

The insulating layer18has an insulation characteristic with a carrier concentration of 6×1015-3×1017/cm3. At this point, the resistance of the insulating layer18is greater than that of heat-treated second conduction type semiconductor layer16.

Since the insulating layer18is formed using a nitride layer in the light emitting device according to the first embodiment, the insulating layer18having a thickness of 0.5-10 μm can be formed. Also, since the insulating layer18is formed using the nitride layer, it can be formed by a general MOCVD equipment.

Referring toFIG. 4, the mask layer17is removed. Therefore, only the insulating layer18remains on the second conduction type semiconductor layer16.

FIG. 7is a view of a second conduction type semiconductor layer where an insulating layer is formed as viewed from the upper side.

Referring toFIG. 7, the insulating layer18is formed along the peripheral portion of the second conduction type semiconductor layer16, and the second conduction type semiconductor layer16is exposed through the central portion.

Referring toFIG. 5, a second electrode layer40is formed on the insulating layer18and the second conduction type semiconductor layer16.

The second electrode layer40can be formed by sequentially depositing an ohmic contact layer19, a reflective layer20, and a metal layer21.

Referring toFIG. 6, the substrate11, the buffer layer12, and the un-doped GaN layer13are removed. The substrate11, the buffer layer12, and the un-doped GaN layer13can be removed by a laser or an etching process.

As the substrate11, the buffer layer12, and the un-doped GaN layer13are removed, the first conduction type semiconductor layer14is exposed, and the upper surface of the first conduction type semiconductor layer14is selectively etched such that it has an uneven surface.

Processing the upper surface of the first conduction type semiconductor layer14such that it has an uneven surface is intended for allowing light from the active layer15to be efficiently emitted.

Also, a first electrode layer22is formed on the first conduction type semiconductor layer14.

Though not shown in detail, the first electrode layer22can include an ohmic contact layer.

As described above, the light emitting device according to the first embodiment provides the insulating layer18between the second electrode layer40and the second conduction type semiconductor layer16along the outer lateral surface of the light emitting device, thereby improving the electrical characteristic of the light emitting device.

FIG. 8is a cross-sectional view explaining a light emitting device according to a second embodiment.

Referring toFIG. 8, a light emitting device includes: a second electrode layer40; a second conduction type semiconductor layer16on the second electrode layer40; an active layer15on the second conduction type semiconductor layer16; a first conduction type semiconductor layer14on the active layer15; and a first electrode layer50on the first conduction type semiconductor layer14.

Also, the second electrode layer40can include a metal layer21, and a reflective layer20and an ohmic contact layer19formed on the metal layer21.

The metal layer21can be formed of at least one of Ti, Cr, Ni, Al, Pt, Au, W, and a conductive substrate. The reflective layer20can be formed of metal including at lease one of Ag, Al, Cu, and Ni having high light reflectivity. The ohmic contact layer19can be a transparent electrode layer, and for example, can be formed of at least one of indium tin oxide (ITO), ZnO, RuOx, TiOx, and IrOx.

The first electrode layer50can include an ohmic contact layer25, a seed layer23formed on the ohmic contact layer25, and a metal layer24formed on the seed layer23.

The ohmic contact layer25can be a transparent electrode layer, and for example, can be formed of at least one of indium tin oxide (ITO), ZnO, RuOx, TiOx, and IrOx.

Also, the insulating layer18is formed between the second electrode layer40and the second conduction type semiconductor layer16along the lateral surface of the light emitting device. The insulating layer18can be a nitride layer in the group III having a thickness of 0.5-10 μm. For example, the insulating layer18can be an AlxGa1-xN layer (0<x≦1).

The central portion of the metal layer21protrudes to the direction in which the second conduction type semiconductor layer16is disposed. The central portions of the reflective layer20and the ohmic contact layer19also protrude to the direction in which the second conduction type semiconductor layer16is disposed.

The upper surface of the first conduction type semiconductor layer14, and the lower surface of the second conduction type semiconductor layer16are not formed to have a uniform height. They have an uneven surface including convex portions and concave portions.

Also, a passivation layer30is formed on the lateral surfaces of the light emitting device.

The passivation layer30can be formed of at least one of SiO2, SiN, Al2O3, SU8, SiON, SiCN, and a nitride in the group III.

Therefore, portions of the metal layer21and the reflective layer20are disposed on the same horizontal plane. Portions of the metal layer21and the ohmic contact layer19are disposed on the same horizontal plane. Also, portions of the metal layer21and the passivation layer30are disposed on the same horizontal plane.

Also, portions of the metal layer21, the insulating layer18, and the passivation layer30can be disposed on the same horizontal plane. Portions of the metal layer21, the reflective layer20, the ohmic contact layer19, the insulating layer18, and the passivation layer30can be disposed on the same horizontal plane.

In the light emitting device according to the second embodiment, the insulating layer18is formed between the second conduction type semiconductor layer16and the second electrode layer40, so that the first conduction type semiconductor layer14or the first electrode layer50is spaced further from the second electrode layer40.

Therefore, short-circuit between the first conduction type semiconductor layer14or the first electrode layer50and the second electrode layer40by an external foreign substance can be prevented.

That is, since the second conduction type semiconductor layer16is formed to have a very thin thickness, short-circuit between the first conduction type semiconductor layer14and the second electrode layer40, or between the first electrode layer50and the second electrode layer40may occur. The light emitting device according to the embodiment can prevent the short-circuit through the insulating layer18.

Particularly, in the light emitting device according to the embodiment, the insulating layer18can be a nitride layer and the nitride layer can be formed with a thick thickness, so that short-circuit is effectively prevented.

Also, the passivation layer30is formed on the outer surfaces of the light emitting device according to the second embodiment, so that short-circuit between the first conduction type semiconductor layer14and the second electrode layer40, or between the first electrode layer50and the second electrode layer40by an external foreign substance can be prevented.

FIGS. 9 to 19are views explaining a method for manufacturing a light emitting device according to the second embodiment.

In description of the method for manufacturing the light emitting device according to the embodiment, manufacturing two light emitting devices on one substrate is exemplary shown for easy understanding of a process of forming the passivation layer30.

Referring toFIG. 9, a substrate11, a buffer layer12, an un-doped GaN layer13, a first conduction type semiconductor layer14, an active layer15, and a second conduction type semiconductor layer16are sequentially formed.

Referring toFIG. 10, the upper surface of the second conduction type semiconductor layer16is selectively etched to form an uneven surface including convex portions and concave portions. At this point, a drying or wet etching process can be used as the etching process.

Referring toFIG. 11, a mask layer17is formed on positions spaced from peripheral portions on the second conduction type semiconductor layer16. The mask layer17can be formed of SiO2or SiN.

Referring toFIG. 12, an insulating layer18is deposited on the second conduction type semiconductor layer16on which the mask layer17is formed.

The insulating layer18can be a nitride layer in the group III. For example, the insulating layer18can be an AlxGa1-xN layer (0<x≦1).

At this point, the insulating layer18does not grow at the central portion where the mask layer17is formed, but grows on only the peripheral portions of the second conduction type semiconductor layer16where the mask layer17is not formed.

The insulating layer18can be grown by flowing tri methyl gallium (TMGa) gas and tri methyl aluminum (TMAl) gas together with a hydrogen gas and an ammonia gas into a chamber at temperature of 600-1200° C.

The insulating layer18has an insulation characteristic with a carrier concentration of 6×1015-3×1017/cm3. At this point, the resistance of the insulating layer18is greater than that of heat-treated second conduction type semiconductor layer16.

Since the insulating layer18is formed using a nitride layer in the light emitting device according to the second embodiment, the insulating layer18having a thickness of 0.5-10 μm can be formed.

Also, since the insulating layer18is formed using the nitride layer, it can be formed by a general MOCVD equipment.

Referring toFIG. 13, the mask layer17is removed. Therefore, only the insulating layer18remains on the second conduction type semiconductor layer16.

Also, an ohmic contact layer19is formed on the second conduction type semiconductor layer16and the insulating layer18.

Referring toFIG. 14, a passivation layer30is formed on the lateral surfaces of the light emitting device.

Referring toFIG. 15, a reflective layer20and a metal layer21are formed on the passivation layer30and the ohmic contact layer19, so that a second electrode layer40is formed.

Referring toFIG. 16, the substrate11, the buffer layer12, and the un-doped GaN layer13are removed.

The substrate11, the buffer layer12, and the un-doped GaN layer13can be removed by a laser or an etching process.

As the substrate11, the buffer layer12, and the un-doped GaN layer13are removed, the first conduction type semiconductor layer14and the passivation layer30are exposed.

Referring toFIG. 17, the upper surface of the first conduction type semiconductor layer14is selectively etched such that it has an uneven surface.

Processing the upper surface of the first conduction type semiconductor layer14such that it has an uneven surface is intended for allowing light from the active layer15to be efficiently emitted.

Referring toFIG. 18, a first electrode layer50is formed on the first conduction type semiconductor layer14.

The first electrode layer50can include an ohmic contact layer25, a seed layer23, and a metal layer24.

Referring toFIG. 19, the two light emitting devices shown inFIG. 18are separated into individual light emitting devices.FIG. 19illustrates one light emitting device separated.

As described above, the light emitting device according to the embodiment provides the insulating layer18between the second electrode layer40and the second conduction type semiconductor layer16along the outer lateral surface of the light emitting device, thereby improving the electrical characteristic of the light emitting device.

Also, the light emitting device according to the embodiment provides the passivation layer30on the lateral sides of the light emitting device, thereby improving the electrical insulation characteristic of the light emitting device.