Highly efficient III-nitride-based top emission type light emitting device having large area and high capacity and method of manufacturing the same

• US 20070040162A1
• Filed: 08/17/2006
• Published: 02/22/2007
• Est. Priority Date: 08/19/2005
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Song, June-O
• Granted Patent: US 7,989,828 B2
• Time in Patent Office: Days
• US Class Current: 257/13
• CPC Class Codes: H01L 33/14 with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/42 Transparent materials

Abstract

Disclosed are a nitride-based top emission type light emitting device and a method of manufacturing the same. The light emitting device includes an n-nitride-based cladding layer, a p-nitride-based cladding layer, a nitride-based active layer, and a multiple p-ohmic contact layer. The multiple p-ohmic contact layer includes at least one pair of ohmic modification layer-transparent conducting layer. The ohmic modification layer includes a poly-crystal nitride layer or an amorphous nitride layer having nitrogen (N) combined with at least one of aluminum (Al), indium (In) and gallium (Ga). The ohmic modification layer is prepared in the form of a droplet or a thin film. Pores or dots are formed on the poly-crystal nitride layer or the amorphous nitride layer so as to provide the multiple p-ohmic contact layer with the photonic crystal effect. The light emitting device represents superior current-voltage characteristics and higher light transmittance.

Claims

1. A nitride-based top emission type light emitting device comprising:

an n-nitride-based cladding layer;

a p-nitride-based cladding layer;

a nitride-based active layer interposed between the n-nitride-based cladding layer and the p-nitride-based cladding layer; and

a multiple p-ohmic contact layer stacked on the p-nitride-based cladding layer, wherein the multiple p-ohmic contact layer includes at least one pair of ohmic modification layer-current spread layer, the ohmic modification layer is not a nitride-based epitaxial layer, but a poly-crystal nitride layer or an amorphous nitride layer having nitrogen (N) combined with at least one of aluminum (Al), indium (In) and gallium (Ga), and the ohmic modification layer has a new phase when the ohmic modification layer is subject to an annealing process such that the ohmic modification layer easily forms a p-ohmic contact through a chemical reaction with the current spread layer stacked on the ohmic modification layer.

2. The nitride-based top emission type light emitting device of claim 1, wherein the current spread layer, which is a transparent conducting layer forming the multiple p-ohmic contact layer, includes a transparent conducting oxide layer or a transparent conducting nitride layer, in which the transparent conducting oxide layer is obtained by combining oxygen (O) with at least one of indium (In), tin (Sn), zinc (Zn), gallium (Ga), cadmium (Cd), magnesium (Mg), beryllium (Be), silver (Ag), molybdenum (Mo), vanadium (V), copper (Cu), iridium (Ir), rhodium (Rh), ruthenium (Ru), tungsten (W), titanium (Ti), tantalum (Ta), cobalt (Co), nickel (Ni), manganese (Mn), platinum (Pt), palladium (Pd), aluminum (Al), and lanthanum (La), and the transparent conducting nitride layer includes transitional metal nitride, which is obtained by combining nitrogen (N) with titanium (Ti), tungsten (W), tantalum (Ta), vanadium (V), chrome (Cr), zirconium (Zr), niobium (Nb), hafnium (Hf), rhenium (Re) or molybdenum (Mo).

3. The nitride-based top emission type light emitting device of claim 1, wherein the ohmic modification layer has a thickness in a range between 0.1 nanometer to 100 nanometer and the current spread layer has a thickness in a range between 1 nanometer to 1000 nanometer.

4. The nitride-based top emission type light emitting device of claim 1, wherein the ohmic modification layer is interposed between the p-nitride-based cladding layer and the current spread layer, and includes a pbly-crystal nitride layer or an amorphous nitride, other than a nitride-based epitaxial layer, in which the poly-crystal nitride layer or the amorphous nitride includes IV-group elements, such as silicon (Si) or germanium (Ge), or II-group elements, such as manganese (Mn), zinc (Zn) or beryllium (Be), in order to improve electrical characteristics at an interfacial surface between the p-nitride-based cladding layer and the current spread layer.

5. The nitride-based top emission type light emitting device of claim 1, wherein the ohmic modification layer is interposed between the p-nitride-based cladding layer and the current spread layer and is prepared in a form of a droplet, a nano-dot or a thin film including at least one of aluminum (Al), indium (In) and gallium (Ga) without using nitrogen (N), in order to improve electrical characteristics at an interfacial surface between the p-nitride-based cladding layer and the current spread layer.

6. The nitride-based top emission type light emitting device of claim 5, wherein the ohmic modification layer is prepared in a form of a droplet, a nano-dot or a thin film including IV-group elements, such as silicon (Si) or germanium (Ge), or II-group elements, such as manganese (Mn), zinc (Zn) or beryllium (Be).

7. The nitride-based top emission type light emitting device of claim 1, wherein pores or dots having various sizes and shapes, such as a circular shape, a triangular shape or a rectangular shape, are formed on the amorphous nitride-based layer or the poly-crystal nitride-based layer through an electrochemical method, a physical method or a chemical method before the current spread layer (transparent conducting layer) is deposited during a process of forming the multiple p-ohmic contact layer, thereby providing the multiple p-ohmic contact layer with a photonic crystal effect.

12. The nitride-based top emission type light emitting device of claim 2, wherein pores or dots having various sizes and shapes, such as a circular shape, a triangular shape or a rectangular shape, are formed on the amorphous nitride-based layer or the poly-crystal nitride-based layer through an electrochemical method, a physical method or a chemical method before the current spread layer (transparent conducting layer) is deposited during a process of forming the multiple p-ohmic contact layer, thereby providing the multiple p-ohmic contact layer with a photonic crystal effect.

13. The nitride-based top emission type light emitting device of claim 3, wherein pores or dots having various sizes and shapes, such as a circular shape, a triangular shape or a rectangular shape, are formed on the amorphous nitride-based layer or the poly-crystal nitride-based layer through an electrochemical method, a physical method or a chemical method before the current spread layer (transparent conducting layer) is deposited during a process of forming the multiple p-ohmic contact layer, thereby providing the multiple p-ohmic contact layer with a photonic crystal effect.

14. The nitride-based top emission type light emitting device of claim 4, wherein pores or dots having various sizes and shapes, such as a circular shape, a triangular shape or a rectangular shape, are formed on the amorphous nitride-based layer or the poly-crystal nitride-based layer through an electrochemical method, a physical method or a chemical method before the current spread layer (transparent conducting layer) is deposited during a process of forming the multiple p-ohmic contact layer, thereby providing the multiple p-ohmic contact layer with a photonic crystal effect.

15. The nitride-based top emission type light emitting device of claim 5, wherein pores or dots having various sizes and shapes, such as a circular shape, a triangular shape or a rectangular shape, are formed on the amorphous nitride-based layer or the poly-crystal nitride-based layer through an electrochemical method, a physical method or a chemical method before the current spread layer (transparent conducting layer) is deposited during a process of forming the multiple p-ohmic contact layer, thereby providing the multiple p-ohmic contact layer with a photonic crystal effect.

16. The nitride-based top emission type light emitting device of claim 6, wherein pores or dots having various sizes and shapes, such as a circular shape, a triangular shape or a rectangular shape, are formed on the amorphous nitride-based layer or the poly-crystal nitride-based layer through an electrochemical method, a physical method or a chemical method before the current spread layer (transparent conducting layer) is deposited during a process of forming the multiple p-ohmic contact layer, thereby providing the multiple p-ohmic contact layer with a photonic crystal effect.

8. A method of manufacturing a nitride-based top emission type light emitting device, the method comprising:

forming a multiple p-ohmic contact layer by repeatedly stacking at least one pair of ohmic modification layer-current spread layer on a p-nitride-based cladding layer of a light emitting structure where an n-nitride-based cladding layer, a nitride-based active layer and the p-nitride-based cladding layer are sequentially stacked on a substrate; and

annealing the multiple p-ohmic contact layer,

wherein the ohmic modification layer includes a poly-crystal nitride layer or an amorphous nitride layer, which is a thin film or a nano-dot obtained by combining nitrogen (N) with at least one of aluminum (Al), indium (In) and gallium (Ga), or the ohmic modification layer is prepared in a form of a droplet, a nano-dot or a thin film without using nitrogen (N).

9. The method of claim 8, wherein the ohmic modification layer includes IV-group elements, such as silicon (Si) or germanium (Ge), or II-group elements, such as manganese (Mn), zinc (Zn) or beryllium (Be) in order to improve electrical characteristics at an interfacial surface between the p-nitride-based cladding layer and the current spread layer.

10. The method of claim 8, wherein a photonic crystal effect is imparted to an upper surface of the p-nitride-based cladding layer in order to improve an external quantum efficiency (EQE) after the ohmic modification layer has been deposited on the p-nitride-based cladding layer.

11. The method of claim 8, wherein the annealing process is performed in a reactor equipped with the multiple p-ohmic contact layer for 3 seconds to 3 hours within a temperature range between a room temperature and 800°

C. under nitrogen (N₂), argon (Ar), helium (He), oxygen (O₂), hydrogen (H₂), air or vacuum atmosphere.