Light emitting device and method of manufacturing the same

A light emitting device is provided. The light emitting device comprises a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer, and an InNO layer. The active layer is disposed on the first conductive semiconductor layer. The second conductive semiconductor layer is disposed on the active layer. The InNO layer is disposed on the second conductive semiconductor layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. 119(e) and 35 U.S.C. 365 to Korean Patent Application No. 10-2008-0085885 (filed on Sep. 1, 2008), which is hereby incorporated by reference in its entirety.

BACKGROUND

The present disclosure relates to a light emitting device.

Extensive research has been conducted recently on devices that use Light Emitting Diodes (LEDs) as devices for emitting light.

LEDs use the characteristics of compound semiconductors to convert electrical signals into light. LEDs have a structure in which a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer are stacked. Here, a power source is applied to the structure to emit light from the active layer.

A first conductive semiconductor layer becomes an N-type semiconductor layer, and a second conductive semiconductor layer becomes a P-type semiconductor layer. Alternatively, a first conductive semiconductor layer may become a P-type semiconductor layer, and a second conductive semiconductor layer may become an N-type semiconductor layer.

On the other hand, an indium-tin oxide (ITO) layer is formed on the second conductive semiconductor layer so that light generated in the active layer may be effectively emitted to the outside. However, high resistance of the ITO layer increases the operating voltage of the LED, thereby increasing power consumption and generated heat.

SUMMARY

Embodiments provide a light emitting device having improved light emission efficiency.

Embodiments also provide a light emitting device having reduced contact resistance between a second conductive semiconductor layer and a second electrode layer.

Embodiments also provide a light emitting device having reduced power consumption and generated heat.

In an embodiment, a light emitting device comprises: a first conductive semiconductor layer; an active layer on the first conductive semiconductor layer; a second conductive semiconductor layer on the active layer; and an InNO layer on the second conductive semiconductor layer.

In an embodiment, a light emitting device comprises: a first conductive semiconductor layer; an active layer on the first conductive semiconductor layer; a second conductive semiconductor layer on the active layer; and an InGaNO layer on the second conductive semiconductor layer.

In an embodiment, a light emitting device comprises: a first conductive semiconductor layer; an active layer on the first conductive semiconductor layer; a second conductive semiconductor layer on the active layer; and an oxide layer including nitrogen on the second conductive semiconductor layer.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the description of embodiments, it will be understood that when a layer (or film), region, pattern or structure is referred to as being ‘on’ or ‘under’ another layer (or film), region, pad or pattern, the terminology of ‘on’ and ‘under’ includes both the meanings of ‘directly’ and ‘indirectly’. Further, the reference about ‘on’ and ‘under’ each layer will be made on the basis of drawings.

In the drawings, the thickness or size of each layer is exaggerated, omitted, or schematically illustrated for convenience in description and clarity. Also, the size of each element does not entirely reflect an actual size.

Hereinafter, a light emitting device according to the embodiments will be described in detail with reference to the accompanying drawings.

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

Referring toFIG. 1, the light emitting device according to the first embodiment includes a substrate10, a buffer layer20on the substrate10, a first conductive semiconductor layer30on the buffer layer20, an active layer40on the first conductive semiconductor layer30, a second conductive semiconductor layer50on the active layer40, and an oxide layer60on the second conductive semiconductor layer50.

Also, the light emitting device includes a first electrode layer70on the first conductive semiconductor layer30, and a second electrode layer80on the oxide layer60.

In the light emitting device, the oxide layer60is disposed between the second electrode layer80and the second conductive semiconductor layer50.

The oxide layer60reduces the contact resistance generated between the second electrode layer80and the second conductive semiconductor layer50to reduce an operating voltage of the light emitting device. Accordingly, power consumption and generated heat of the light emitting device may be reduced, and light emission efficiency may be increased.

The oxide layer60includes an InNO layer or an InGaNO layer.

For example, the InNO layer may be formed by forming an InN layer on the second conductive semiconductor layer50and oxidizing the InN layer.

For example, the InGaNO layer may be formed by forming an In rich InGaN layer on the second conductive semiconductor layer50and oxidizing the In rich InGaN layer. The In rich InGaN layer may become an InxGa1−xN layer (where 0.7≦x<1), and the InGaNO layer may become an InxGa1−xNO layer (where 0.7≦x<1).

Hereinafter, a method of manufacturing the light emitting device as described above will be fully described.

A substrate10is prepared. A buffer layer20is formed on the substrate10.

The substrate10may be formed of at least one of Al2O3, Si, SiC, GaAs, ZnO, and MgO.

The buffer layer20reduces a difference of the lattice constant between the substrate10and a semiconductor layer on the substrate10. For example, the buffer layer20may be formed in a stacked structure such as AlInN/GaN, InxGa1−xN/GaN and AlxInyGa1−x−yN/InxGa1−xN/GaN.

The buffer layer20may be formed by injecting TMGa and TMIn of 3×105mol/min, and TMAl of 3×106mol/min in addition to a hydrogen gas and an ammonia gas into a chamber where the substrate10is located.

Also, an undoped GaN layer may be formed between the buffer layer20and the first conductive semiconductor layer30.

A first conductive semiconductor layer30, an active layer40and a second conductive semiconductor layer50are formed on the buffer layer20.

The first conductive semiconductor layer30may be a nitride semiconductor layer doped with a first conductive impurity. For example, the first conductive semiconductor layer may be formed by providing a silane gas (SiH4) including NH3(3.7×10−2mol/min), TMGa (1.2×10−4mol/min), and an N-type impurity such as Si.

The active layer40may be formed in a single quantum well structure or a multiple quantum well structure, or may be formed in a stacked structure of InGaN well layer/GaN barrier layer. For example, the active layer40may be formed at an atmosphere of nitrogen by injecting a trimethyl gallium and a trimethyl indium using a Metal Organic Chemical Vapor Deposition (MOCVD).

The second conductive semiconductor layer50may be a nitride semiconductor layer doped with a second conductive impurity. For example, the second conductive semiconductor layer50may be formed by supplying a TMGa gas (7×10−6mol/min), bis-ethylcyclopentadienyl magnesium EtCp2Mg {Mg(C2H5C5H4)2} (5.2×10−7mol/min), and NH3(2.2×10−1mol/min) using a hydrogen gas as a carrier gas.

The oxide layer60is formed on the second conductive semiconductor layer50.

The oxide layer60may be formed using an InNO layer or an InGaNO layer. The InNO layer or InGaNO layer is formed by performing an oxidation process on an InN layer and or an In rich InGaN layer after forming the InN layer or the In rich InGaN layer on the second conductive semiconductor layer50.

The InN layer is formed by injecting a TMIn gas and an NH3gas into MOCVD equipment at a temperature of about 400□ to about 700□. The In rich InGaN layer is formed by injecting a TMIn gas, a TMGa gas and an NH3gas into MOCVD equipment at a temperature of about 400□ to about 700□.

The oxidation process may be performed through a dry oxidation process under an O2atmosphere in RTP equipment, PECVD equipment, and RIE equipment. According to another embodiment, the oxidation process may be performed through a wet oxidation process.

Next, the oxide layer60, the second conductive semiconductor layer50, the active layer40, and the first conductive semiconductor layer30are selectively removed through a mesa etching to upwardly expose a portion of the first conductive semiconductor layer30.

Then, a first electrode layer70is formed on the first conductive semiconductor layer30, and a second electrode layer80is a oxide layer60.

Accordingly, the light emitting device as described inFIG. 1according to the first embodiment may be manufactured.

FIG. 2is a cross-sectional view of a light emitting device according to a second embodiment. Hereinafter, only the difference from the first embodiment will be described.

Referring toFIG. 2, the light emitting device according to the second embodiment includes an InN layer or an In rich InGaN layer61between an oxide layer60and a second conductive semiconductor layer50.

While, in the first embodiment, the oxide layer60is disposed on the second conductive semiconductor layer50by forming an InN layer or an InGaN layer to completely oxidize into an InNO layer or an InGaNO layer, the oxide layer60is formed by partially oxidizing only an upper portion of the InN layer or the In rich InGaN layer61to form an oxide layer60, InNO layer or In rich InGaNO layer in the second embodiment.

That is, in the second embodiment, the InN layer or In rich InGaN layer61is formed on the second conductive semiconductor layer50, and the oxide layer60is formed on the InN layer or the In rich InGaN layer61.

FIG. 3is a cross-sectional view of a light emitting device according to a third embodiment. Hereinafter, only the difference from the first embodiment will be described.

ReferringFIG. 3, the light emitting device according to the third embodiment includes a third conductive semiconductor layer62between an oxide layer60and a second conductive semiconductor layer50.

The oxide layer60is formed of an InNO layer or an InGaNO layer to have strong characteristics of an N-type impurity. However, the contact resistance may be high. In order to complement this, the third conductive semiconductor layer62is disposed between the oxide layer60and the second conductive semiconductor layer50.

The third conductive semiconductor layer62may be formed of a GaN layer or an InGaN layer including an N-type impurity, Si, and be formed in a thickness of about 2 nm to about 10 nm.

The third conductive semiconductor layer62can enhance the current spreading effect.

FIG. 4is a cross-sectional view of a light emitting device according to a fourth embodiment. Hereinafter, only the difference from the first embodiment will be described.

Referring toFIG. 4, the light emitting device according to the fourth embodiment includes an indium-tin oxide (ITO) layer63on an oxide layer60, having a different composition from the oxide layer60.

Since being disposed on the oxide layer60, the ITO layer63has an advantage of smaller contact resistance than an ITO layer disposed on a second conductive semiconductor layer in the related-art.

In above first to fourth embodiment, the oxide layer60may be formed in a thickness of about 1 nm to about 100 nm by oxidizing an InN layer or an In rich InGaN layer. Here, the In rich InGaN layer may be an InxGa1−xN layer (where 0.7≦x<1).

Also, the oxide layer60may include N-type impurities. For example, the oxide layer60may be an InNO layer or an In rich InGaNO layer including Si.

As described above, light emitting devices according to the embodiments can reduce contact resistance by forming an InNO layer or an In rich InGaNO layer between the second conductive semiconductor layer and the second electrode layer, and enhance light emission efficiency by reducing power consumption and generated heat of the light emitting device.