KR20090002190A - Nitride semiconductor light-emitting device and manufacturing method thereof - Google Patents

Abstract

The nitride semiconductor light emitting device according to the present invention includes an n-type semiconductor layer or a nitride series crystal substrate; An active layer formed on the n-type semiconductor layer or the crystal substrate and having a nano-rod doped with a predetermined material; And a p-type semiconductor layer formed on the active layer. The method of manufacturing a nitride semiconductor light emitting device according to the present invention comprises the steps of forming an n-type semiconductor layer or a nitride-based crystal substrate; Forming an active layer having a nano-rod doped with a predetermined material on the n-type semiconductor layer or a nitride-based crystal substrate; And forming a p-type semiconductor layer on the active layer.

According to the present invention, since the lattice defect and the thermal expansion coefficient defect are significantly reduced, there is an effect of improving the electrical characteristics and optical characteristics of the light emitting device. In addition, due to the nanorod structure, the environment in which the quantum dots can be formed is improved, thus enabling current spreading in a wider area and reducing leakage current.

Description

Nitride semiconductor light emitting device and manufacturing method thereof

1 is a side cross-sectional view schematically showing the components of a typical nitride semiconductor light emitting device.

2 is a side cross-sectional view schematically showing the components of the nitride semiconductor light emitting device according to the first embodiment of the present invention.

Figure 3 is a side cross-sectional view schematically showing the components of the nitride semiconductor light emitting device according to the second embodiment of the present invention.

Figure 4 is a side cross-sectional view schematically showing the components of the nitride semiconductor light emitting device according to the third embodiment of the present invention.

5 is a side cross-sectional view schematically showing the components of a nitride semiconductor light emitting device according to the fourth embodiment of the present invention.

<Explanation of symbols for main parts of drawing>

100, 200, 300, and 400: nitride semiconductor light emitting device according to the present invention

110: crystal substrate layer 210, 310, 410: substrate layer

220, 320, 420: n-type semiconductor layer 120, 230, 330, 430: first active layer

130, 240, 340, and 440: second active layer 350: third active layer

122, 232, 342, 442: nanorods 140, 250, 360, 450: p-type semiconductor layer

The present invention relates to a nitride semiconductor light emitting device and a method of manufacturing the same.

In general, a semiconductor light emitting device (LED) is a light emitting diode (LED), which is used to send and receive signals by converting electrical signals into infrared, visible or light forms using the characteristics of compound semiconductors. It is an element.

The use range of LED is used in home appliances, remote controllers, electronic signs, indicators, and various automation devices, and the types are divided into IRED (Infrared Emitting Diode) and VLED (Visible Light Emitting Diode).

In general, miniaturized LEDs are made of a surface mount device type for direct mounting on a printed circuit board (PCB) board. Accordingly, LED lamps, which are used as display elements, are also being developed as surface mount device types. These surface-mount devices can replace the existing simple lighting lamps, which are used for lighting indicators of various colors, character display and image display.

As the area of use of LEDs becomes wider as described above, required luminances such as electric lamps used for living, electric lamps for rescue signals, and the like become higher and higher, and in recent years, development of high output light emitting diodes is actively underway.

In particular, many researches and investments have been made on semiconductor optical devices using Group 3 and Group 5 compounds such as GaN (gallium nitride), AlN (aluminum nitride), and InN (indium nitride). This is because the nitride semiconductor light emitting device has a bandgap of a very wide region ranging from 1.9 eV to 6.2 ev, and thus has the advantage of realizing three primary colors of light using the same.

Recently, the development of blue and green light emitting devices using nitride semiconductors has revolutionized the optical display market and is considered as one of the promising industries that can create high added value in the future. However, as mentioned above, in order to pursue more industrial use in such a nitride semiconductor optical device, increasing light emission luminance is also a problem to be taken first.

1 is a side cross-sectional view schematically showing the components of a typical nitride semiconductor light emitting device 10.

Referring to FIG. 1, a general nitride semiconductor light emitting device 10 includes a substrate 11, a buffer layer 12, an undoped-GaN layer 13, an n-type semiconductor layer 14, an active layer 15, and a p-type semiconductor layer ( 16), insulating film 17, p-electrode 18, n-electrode 19 and the like.

The substrate 11 is made of sapphire or SiC, and a buffer layer 12 having a polycrystalline thin film structure of, for example, an Al _y Ga _1-y N layer is grown on the substrate 11 at a low temperature.

When the buffer layer 12 is grown, an Undoped-GaN layer 13 is grown thereon to increase lattice match, and an N-type semiconductor layer (GaN layer) 14 doped with Si (silicon) is formed.

An active layer 15 is stacked on the n-type semiconductor layer 14, and a p-type semiconductor layer (GaN layer) 16 doped with Mg (magnesium) is formed on the active layer 15. As a multiple quantum well (MQW) structure, holes flowing through the p-type semiconductor layer 16 and electrons flowing through the n-type semiconductor layer 14 are combined to generate light.

In addition, an insulating film 17 is formed on the n-type semiconductor layer 14 and the p-type semiconductor layer 16, and an n-electrode 19 and a p-electrode 18 are formed on the insulating film 17, respectively, to form a semiconductor light emitting device. To form (10).

As described above, when the semiconductor layer is grown on the substrate 11, by using a substrate that is lattice matched with the semiconductor to be grown, there are few crystal defects and the semiconductor having good crystallinity can be grown. However, there are currently no substrates lattice matched with nitride semiconductors, excellent in crystallinity, and capable of stably growing nitride semiconductor crystals, and as a substitute, sapphire, spinel (MgAl ₂ O ₄ ) And substrates that are not lattice matched with nitride semiconductors such as silicon carbide.

Since the buffer layer 12 formed to implement an optical device such as a nitride semiconductor light emitting device or a laser serves to buffer stress between the substrate 11 and a layer grown thereon, sapphire, SiC, Si, or the like According to the type of substrate, a buffer layer growth technology using materials such as GaN and AlGaN is applied.

However, first of all, since the difference in crystal lattice constant between the buffer layer 12 and the substrate 11 is large, the buffer layer 12 may have a dislocation or attacker between the layer grown on the substrate 11 and the buffer layer 12. Lattice defects such as vacancy occur.

In addition, in the case of using a Si substrate, a high temperature environment is required to grow a nitride semiconductor layer including an epi layer, and a natural n-type doping effect is performed on a growing nitride layer because Si diffuses into the nitride layer during high temperature growth. effects may occur to deteriorate the crystallinity of the nitride layer or to make conduction control difficult.

In addition, when growing, for example, a hexagonal structure (Al _x Ga _1-x ) _1-y InN _y layer on a cubic Si wafer, epitaxy may be particularly used. The lattice mismatch due to the different crystal structures causes the Si wafer and the (Al _x Ga _1-x ) _1-y InN _y layer to be separated from each other as a semiconductor device unless there is an operation technique for the semiconductor device. The function is almost impossible.

Accordingly, the substrate and the nitride layer on the substrate must be made of high quality crystal lattice bonds to reduce crystal mismatch with each other.

The present invention provides a nitride semiconductor light emitting device having excellent crystal lattice bonding properties without lattice defects on a substrate and of which good quality quantum dots can be formed.

In addition, the present invention provides a method of manufacturing a nitride semiconductor light emitting device capable of suppressing the diffusion of current and leakage current, which is an electrical characteristic of the device, while functioning as a quantum dot seed while having a low defect density.

The nitride semiconductor light emitting device according to the present invention includes an n-type semiconductor layer or a nitride series crystal substrate; An active layer formed on the n-type semiconductor layer or the crystal substrate and having nanorods doped with a predetermined material; And a p-type semiconductor layer formed on the active layer.

The method of manufacturing a nitride semiconductor light emitting device according to the present invention comprises the steps of forming an n-type semiconductor layer or a nitride-based crystal substrate; Forming an active layer having a nano-rod doped with a predetermined material on the n-type semiconductor layer or a nitride-based crystal substrate; And forming a p-type semiconductor layer on the active layer.

Hereinafter, a method of manufacturing a nitride semiconductor light emitting device and a nitride semiconductor light emitting device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. For convenience of understanding, a stacked structure of a nitride semiconductor light emitting device and a method of manufacturing the same are described. Let's explain together.

2 is a side cross-sectional view schematically showing the components of the nitride semiconductor light emitting device 100 according to the first embodiment of the present invention.

Referring to FIG. 2, the nitride semiconductor light emitting device 100 according to the first embodiment of the present invention may include a crystal substrate layer 110, a first active layer 120, a second active layer 130, and a p-type semiconductor layer 140. The first active layer 120 is a kind of nanorod layer in which nanorods are formed, and the crystal substrate layer 110 is a nitride-based material. It is assumed that the substrate layer is provided.

The GaN crystal substrate layer 110 may be grown by HVPE (Hydride Vapor Phase Epitaxy) technology, Molecular Beam Epitaxy (MBE) technology, Atomic Layer Deposition (ALD) technology, or the like.

Subsequently, the first active layer 120 having the nanorods 122 formed thereon is grown on the GaN crystal substrate layer 110. In order to form the nanorods 122, a mask pattern is deposited on the GaN crystal substrate layer 110. , GaN layer is grown.

The mask pattern has a nanometer-based pattern structure, and the GaN layer is formed in a temperature environment of about 700 ° C to 1200 ° C. For example, a SiO2 or SiNx mask pattern may be used as the mask pattern.

After the GaN layer is formed, when the mask pattern is removed, a columnar space (that is, a space for forming the nanorods 122) is created, and the semiconductor material doped with the predetermined material is grown (filled) by the space. Nanorod 122 may be completed.

The nanorods 122 may be formed by, for example, Si, In, Ga, Al, or the like, or may be filled with gallium nitride doped with a material in combination thereof.

The column-shaped space, that is, the narrow rod 122 may be formed in the form of a column whose cross section is circular, stripe or rhombus, where the diameter (when the cross section is circular). In the case of the rhombus, the length of the sides, or the interval (thickness) in the case of the striped form may be formed to about 100 nm to 3 μm.

At this time, the column rods 122 of each column type may be formed in parallel so as not to contact each other (non-coalesce).

In an embodiment of the present invention, the process of forming the first active layer 120, that is, the deposition of the mask pattern, the growth of the GaN layer, the removal of the mask pattern, and the doping material injection into the nanorod space may be repeatedly performed. The depth and directivity of the nanorods 122 may be controlled through an iterative process. The repetitive process may be treated through an ex-situ process.

When the second active layer 130 is grown on the first active layer 120, a quantum dot (QD) is formed around the nanorods 122. The nanorods 122 may be formed at a density of about 10 ⁸ / cm ² to 10 ¹⁰ / cm ² on the first active layer 120.

At this time, an important factor among the conditions for forming the nanorods 122 is a defect density of the GaN layer (first active layer 120) on which the nanorods 122 are formed, and has a low defect density of at least 10 ⁶ / cm ² or less. It should have a numerical value (ie, the defect density figures of the GaN layer are closely related to the size and density of the nanorods).

In the case of a semiconductor layer having a defect density value of 10 ⁸ / cm ³ or more, it is difficult to obtain an active layer having quantum dots around the nanorods 122 as in the present invention, and in particular, the optical property according to crystal quality is IQE ) May also cause a decrease.

In order to improve the performance of the IQE aspect, the lattice defects and the misalignment coefficients (Miss orientation) between the GaN crystal substrate layer 110 and the first active layer 120 should be controlled, and thus, the GaN layer having a low defect density should be adjusted. And to form the nanorods 122 in the GaN layer in order to control the induction production of quantum dots.

In addition, the doped nanorods 122 improve current characteristics-current spreading and injection due to crystal defects at the interface between the first active layer 120, the second active layer 130 and the lower layer, and leak This prevents a phenomenon in which device characteristics are degraded by a current.

When the first active layer 120 is formed, a second active layer 130 is formed thereon.

The second active layer 130 generates light by combining holes flowing through the p-type semiconductor layer 140 and electrons flowing through the GaN crystal substrate layer 110. The second active layer 130 generates light by the excitation level or energy band gap difference of the quantum well. The light of the corresponding energy is emitted.

The second active layer 130 may be grown, for example, in a multi-quantum well (MQW) structure composed of InGaN / GaN using a MOCVD (Metal Organic Chemical Vapor Deposition) method.

When the active layer 130 is formed, the temperature of the atmosphere is raised to 1000 ° C. using hydrogen as a carrier gas, TMGa (7 × 10 ⁻⁶ mol / min), trimethylaluminum (TMAl) (2.6 × 10 ⁻⁵ mol / min), Bicetyl cyclopentadienyl magnesium (EtCp2Mg) {Mg (C ₂ H ₅ C ₅ H ₄ ) ₂ } (5.2 x 10 ^-7 mol / min), and NH ₃ (2.2 x 10 ^-1 mol / min) was fed The p-type semiconductor layer 140 is grown.

Subsequently, for example, heat treatment is performed at a temperature of 950 ° C. for 5 minutes to adjust the maximum hole concentration of the p-type semiconductor layer 140.

As such, when the basic stacked structure from the GaN crystal substrate layer 110 to the p-type semiconductor layer 140 is implemented, an n-type electrode made of titanium (Ti) or the like is deposited under the GaN crystal substrate 110. A p-type electrode made of nickel (Ni) or the like is deposited on the p-type semiconductor layer 140. The p-type electrode may be implemented as a transparent electrode made of one of ITO, ZnO, RuOx, TiOx, and IrOx (the electrode is not shown). Not).

As such, since the GaN crystal substrate layer 110 serves as an n-type contact layer, the nitride semiconductor light emitting device 100 according to the first embodiment of the present invention may be manufactured in a vertical structure.

Hereinafter, the nitride semiconductor light emitting device 200 according to the second embodiment of the present invention will be described with reference to FIG. 3.

3 is a side cross-sectional view schematically showing the components of the nitride semiconductor light emitting device 200 according to the second embodiment of the present invention.

Referring to FIG. 3, the nitride semiconductor light emitting device 200 according to the second embodiment of the present invention may include a substrate layer 210, an n-type semiconductor layer 220, a first active layer 230, and a second active layer 240. And a p-type semiconductor layer 250.

That is, the nitride semiconductor light emitting device 200 according to the second embodiment of the present invention differs from the first embodiment in that the second embodiment instead of the crystal substrate layer 110 of the first embodiment differs from the substrate layer 210. The n-type semiconductor layer 220 is provided.

As the substrate layer 210, all kinds of substrates capable of growing a nitride-based material may be used. For example, sapphire, Si (silicon), SiC (silicon carbide), GaAs (gallium arsenide), ZnO (zinc oxide) ) Or MgO (magnesium oxide), or the like, but in the embodiment of the present invention, a sapphire substrate is used.

An n-type semiconductor layer 220 is formed on the substrate layer 210. The n-type semiconductor layer 220 is formed of an n-type GaN semiconductor layer, and is called Epitaxial Lateral Overgrowth (“ELO”). Low defect density of 10 ⁶ / cm ² or less using the deposition technique.

In general, in the case of a substrate layer such as sapphire or SiC substrate, when the GaN semiconductor layer is grown, it has a defect density of about 10 ⁸ to 10 ⁹ / cm 2. However, when the side growth method such as ELO is used, the defect density may be reduced by several orders or more due to the property that dislocation is not well transmitted in the horizontal direction.

The ELO deposition technique includes growing nitride semiconductor crystals growing on windows adjacent to each other from portions exposed through patterning to the substrate layer 210 until they coalesce on the top surface of the selective growth mask.

The first active layer 230 including the nanorods 132 is formed on the n-type semiconductor layer 220 having the low defect density as described above. A description of the formation process of the first active layer 230 and the second active layer 240 is performed. ) And the functional description in which the quantum dots are formed around the interface between the first active layer 230 is similar to the first embodiment described above, and thus repeated descriptions thereof will be omitted.

In addition, by the doped nanorods 232, the current characteristics due to crystal defects at the interface between the first active layer 230, the second active layer 240 and the lower layer-current spreading and injection-is improved, Similarly to the first embodiment, the effect of preventing the phenomenon of deterioration of device characteristics due to leakage current can be obtained.

A second active layer 240 is formed on the first active layer 230, a p-type semiconductor layer 250 is formed on the second active layer 240, and a p-side electrode and an n-side electrode are formed. The nitride semiconductor light emitting device according to the second embodiment is completed.

Hereinafter, the nitride semiconductor light emitting device 300 according to the third embodiment of the present invention and the nitride semiconductor light emitting device 400 according to the fourth embodiment, which will be described with reference to FIGS. 4 and 5, are core technologies of the present invention. The nanorods 342 and 442 may be differentiated according to the formation position. The configuration and operation of the basic semiconductor layer and the process of forming the nanorods 342 and 442 are similar to those described above. Shall be.

4 is a side cross-sectional view schematically showing the components of the nitride semiconductor light emitting device 300 according to the third embodiment of the present invention.

Referring to FIG. 4, the nitride semiconductor light emitting device 300 according to the third embodiment of the present invention includes a substrate layer 310, an n-type semiconductor layer 320, a first active layer 330, a second active layer 340, And a third active layer 350 and a p-type semiconductor layer 360.

In the third embodiment of the present invention, the nanorod 342 is formed on the second active layer 340.

The nanorod 342 of the second active layer 340 is formed by a mask pattern and is doped by a material such as Si, In, Ga, Al, etc., similar to the above-described first and second embodiments. However, the effects obtained by forming the nanorods 342 between the active layers, that is, between the first active layer 330 and the third active layer 350 are differentiated.

The nanorods 342 are formed in the second active layer 340 between the first active layer 330 and the third active layer 350, so that the nanorods 342 are in contact with the interface between the first active layer 330 and the third active layer 350. Quantum dot formation can be more active, thus increasing carrier suppression and having a high bandgap.

Accordingly, as the recombination rate of holes and electrons is improved on the active layers 330, 340, and 350, and the recombination emission rate is improved, the light emitting efficiency of the nitride semiconductor light emitting device may be increased.

5 is a side cross-sectional view schematically showing the components of the nitride semiconductor light emitting device 400 according to the fourth embodiment of the present invention.

Referring to FIG. 5, the nitride semiconductor light emitting device 400 according to the fourth embodiment of the present invention includes a substrate layer 410, an n-type semiconductor layer 420, a first active layer 430, a second active layer 440, and and a p-type semiconductor layer 450, which is different from the first to third embodiments described above in that the nanorods 442 are formed between the active layers 430 and 440 and the p-type semiconductor layer 450. It is a point formed at an interface.

In the third and fourth embodiments of the present invention, the substrate layer 410 and the n-type semiconductor layer 420 are used, but may be provided as the crystal substrate layer 110 as in the first embodiment. Of course.

The nanorod 442 according to the fourth embodiment of the present invention may be formed by a mask pattern method using photography similar to the above-described method, and may be doped with a material such as Si, In, Ga, Al, or the like.

As the nanorods 442 are formed in the second active layer 440, bending occurs at an interface between the p-type semiconductor layer 450 and the second active layer 440 (an uneven structure is formed to roughen the surface). ), The light emitting area combined with holes and electrons is formed to be wider to maximize the light emitting efficiency of the nitride semiconductor light emitting device.

According to the embodiments of the present invention, first, the nanorods 122, 232, 342, and 442 are formed at an interface between the active layers 130 and 230 and the crystal substrate layer 110 or the n-type semiconductor layer 220. Or, second, between the active layers 330 and 350, or third, at the interface between the p-type semiconductor layer 450 and the active layer 430. The nanorods 122, 232, 342 and 442 It should be noted that the above embodiments can be combined and formed in plural.

Although the present invention has been described above with reference to the embodiments, these are only examples and are not intended to limit the present invention, and those skilled in the art to which the present invention pertains may have an abnormality within the scope not departing from the essential characteristics of the present invention. It will be appreciated that various modifications and applications are not illustrated. For example, each component specifically shown in the embodiment of the present invention 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.

According to the method of manufacturing the nitride semiconductor light emitting device and the nitride semiconductor light emitting device according to the present invention has the following effects.

First, according to the present invention, since lattice defects and thermal mismatch between the substrate and the semiconductor layer are significantly reduced, the density of defects can be lowered, thereby improving the electrical and optical characteristics of the light emitting device. It works.

Second, since the nanorods are provided between the active layer and the n-type semiconductor layer (or crystal substrate layer) or the active layer, the environment in which the quantum dots can be formed is improved, thus enabling current diffusion in a wider area and reducing leakage current. It is effective.

Third, since the nanorods are provided between the p-type semiconductor layer and the active layer, the light emitting area is widened, and thus the luminous efficiency is improved, and the rod can easily control the induction generation of quantum dots.

Claims (17)

n-type semiconductor layer or nitride-based crystal substrate; An active layer formed on the n-type semiconductor layer or the crystal substrate and having a nano-rod doped with a predetermined material; And A nitride semiconductor light emitting device comprising a p-type semiconductor layer formed on the active layer. The method of claim 1, wherein the active layer A first active layer formed on the n-type semiconductor layer or the crystal substrate; A second active layer formed on the first active layer and in which the nanorods are formed; And A nitride semiconductor light emitting device comprising a third active layer formed on the second active layer. The method of claim 1, wherein the active layer A first active layer formed on the n-type semiconductor layer or the crystal substrate and having the nanorods formed thereon; And A nitride semiconductor light emitting device comprising a second active layer formed on the first active layer. The method of claim 1, wherein the active layer A first active layer formed on the n-type semiconductor layer or a nitride-based crystal substrate; And A nitride semiconductor light emitting device formed on the first active layer and including a second active layer having the nanorods formed thereon. The method of claim 1, wherein the crystal substrate is A nitride semiconductor light emitting device which is a GaN crystal substrate. The method of claim 1, wherein the n-type semiconductor layer A nitride semiconductor light emitting device formed using an epitaxial lateral overgrowth (ELO) deposition technique. The method of claim 1, wherein the crystal substrate is A nitride semiconductor light emitting device having a low defect density of 10 ⁶ / cm ² or less. The method of claim 1, wherein the predetermined material A nitride semiconductor light emitting device comprising at least one material of Si, In, Ga, Al. The method of claim 1, wherein the active layer A nitride semiconductor light emitting device comprising a nitride semiconductor layer having a rod formed therein. The method of claim 1, wherein the narrow rod A nitride semiconductor light emitting device formed in a temperature environment of 700 ℃ to 1200 ℃. The method of claim 1, wherein the nanorods A nitride semiconductor light emitting device formed at a density of 10 ⁸ / cm ² to 10 ¹⁰ / cm ² . forming an n-type semiconductor layer or a nitride-based crystal substrate; Forming an active layer having a nano-rod doped with a predetermined material on the n-type semiconductor layer or a nitride-based crystal substrate; And A method of manufacturing a nitride semiconductor light emitting device comprising the step of forming a p-type semiconductor layer on the active layer. The method of claim 12, wherein the forming of the active layer Forming a first active layer on the n-type semiconductor layer or the crystal substrate; Forming a second active layer having the nanorods formed on the first active layer; Filling the inside of the furnace rod with a semiconductor material doped with a predetermined material; And A method of manufacturing a nitride semiconductor light emitting device comprising the step of forming a third active layer on the second active layer. The method of claim 12, wherein the forming of the active layer Forming a first active layer having the nanorods formed on the n-type semiconductor layer or the crystal substrate; Filling the inside of the nanorods with a semiconductor material doped with a predetermined material; And A method of manufacturing a nitride semiconductor light emitting device comprising the step of forming a second active layer on the first active layer. The method of claim 12, wherein the forming of the active layer Forming a first active layer on the n-type semiconductor layer or the nitride-based crystal substrate; Forming a second active layer having the nanorods formed on the first active layer; And The nanorods are filled with a semiconductor material doped with a predetermined material inside the manufacturing method of the nitride semiconductor light emitting device. The method of claim 12, wherein the forming of the active layer Gallium nitride is grown in the nanorods, and the gallium nitride is doped with at least one material of Si, In, Al. The method of claim 12, wherein the forming of the active layer The nanorods are formed using a mask pattern in nanometer units manufacturing method of a nitride semiconductor light emitting device.

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