WO2017039045A1 - Semiconductor light-emitting device - Google Patents

Abstract

A semiconductor light-emitting device capable of improving light-emitting efficiency is disclosed. The semiconductor light-emitting device comprises an n-type semiconductor layer, a quantum well layer, a barrier layer, and a p-type semiconductor layer. The n-type semiconductor layer comprises an I-VII compound semiconductor. The quantum well layer is formed on the n-type semiconductor layer and comprises the I-VII compound semiconductor. The barrier layer is formed on the quantum well layer and comprises the I-VII compound semiconductor. The p-type semiconductor layer is formed on the barrier layer and comprises the I-VII compound semiconductor, wherein one or more p-type local doping layers are formed at the barrier layer.

Description

Semiconductor light emitting device

The present invention relates to a light emitting device, and more particularly to a semiconductor light emitting device.

Semiconductor light emitting devices such as light emitting diodes are environmentally friendly, capable of low power driving, and can be implemented in a small size. Due to these advantages, since semiconductor light emitting devices have been developed, such semiconductor light emitting devices have been widely used in various fields. In particular, since the development of the III-V nitride-based quantum well structure-based semiconductor light emitting device, it is possible to implement white light, and has been gradually expanding the range of application to not only LCD TV backlight but also general lighting. .

Meanwhile, although a III-V nitride-based quantum well structure-based semiconductor light emitting device has been developed, a sapphire substrate is used for nitride semiconductor growth, but there is a problem that it is very expensive. In addition, group II-V / I-VII semiconductors can use ZnO substrates that have higher luminous efficiency than nitride semiconductors, are cheaper than sapphire, and have large area substrates, but are still used for p-doping to form devices. This situation is not solved.

Accordingly, I-VII compound semiconductor light emitting devices have been developed. Since the I-VII compound semiconductor light emitting device has a lattice constant similar to that of silicon, it can be grown on an inexpensive silicon substrate and a large-sized silicon wafer with a diameter of 30 cm can be used as the substrate, thereby significantly reducing manufacturing costs. . In addition, the luminous efficiency is known to be relatively superior to the nitride semiconductor.

1 is a diagram schematically showing a band structure of a conventional I-VII compound semiconductor light emitting device.

Referring to FIG. 1, the electron blocking layer prevents electrons passing through the quantum well from moving to the p-type region to improve luminous efficiency.

It is a structure of a conventional electron blocking layer. As can be seen in FIG. 1, the electron blocking layer blocks electrons moving along the path a to block the movement of the p-type semiconductor layer, but holes are injected from the p-type semiconductor layer along the path b. It acts as a potential barrier Vb with respect to. Therefore, as the hole density of the quantum well layer is reduced, the luminous efficiency acts as a cause. Moreover, the heavy effective mass of the hole and the internal field caused by piezo and spontaneous polarization also contribute to the poor hole injection efficiency.

An object of the present invention is to provide a semiconductor light emitting device that can improve luminous efficiency.

Semiconductor light emitting devices according to exemplary embodiments of the present invention for solving this problem include an n-type semiconductor layer, a quantum well layer, a barrier layer and a p-type semiconductor layer. The n-type semiconductor layer includes an I-VII compound semiconductor. The quantum well layer is formed on the n-type semiconductor layer, and includes an I-VII compound semiconductor. The barrier layer is formed over the quantum well layer and includes an I-VII compound semiconductor. The p-type semiconductor layer is formed on the barrier layer and includes an I-VII compound semiconductor. At this time, at least one p-type local doping layer is formed on the barrier layer.

Preferably, the p-type local doping layer may be formed adjacent to the quantum well layer.

In this case, the n-type semiconductor layer, the quantum well layer, the barrier layer and the p-type semiconductor layer are CuFCl, CuBrF, CuFI, CuClBr, CuClI, CuBrI, AgFCl, AgFBr, AgFI, AgClBr, AgClI, AgBrI, AuFCl, AuFBr, AuFI, AuClBr, AuClI, AuBrI, CuFClBr, CuFClI, CuFBrI, CuIBrCl, AgFClBr, AgFClI, AgFBrI, AgClBrI, AuFClBr, AuFClI, AuFBrI, or AuClBrI, which may contain at least one.

Meanwhile, the semiconductor light emitting device may further include one or more electron blocking layers formed between the barrier layer and the p-type semiconductor layer.

In this case, the p-type local doping layer formed on the barrier layer is preferably spaced apart from the electron blocking layer by more than 10nm.

In addition, at least one p-type local doping layer may be formed on the electron blocking layer.

In addition, the electron blocking layer is CuFCl, CuBrF, CuFI, CuClBr, CuClI, CuBrI, AgFCl, AgFBr, AgFI, AgClBr, AgClI, AgBrI, AuFCl, AuFBr, AuFI, AuClBr, AuClI, AuBrI, CuFClBr, CuBrI, IBIB It may include at least one of, AgFClBr, AgFClI, AgFBrI, AgClBrI, AuFClBr, AuFClI, AuFBrI, or AuClBrI.

A semiconductor light emitting device according to another exemplary embodiment of the present invention includes a substrate, an n-type semiconductor layer, a quantum well layer, a barrier layer, an electron blocking layer, and a p-type semiconductor layer. The n-type semiconductor layer is formed on the substrate and includes an I-VII compound semiconductor. The quantum well layer is formed on the n-type semiconductor layer, and includes an I-VII compound semiconductor. The barrier layer is formed on the quantum well layer and includes an I-VII compound semiconductor. The electron blocking layer is formed on the barrier layer and includes an I-VII compound semiconductor. The p-type semiconductor layer is formed on the electron blocking layer and includes an I-VII compound semiconductor. In this case, at least one p-type local doping layer is formed on the electron blocking layer.

For example, the n-type semiconductor layer, the quantum well layer, the barrier layer, and the p-type semiconductor layer may be CuFCl, CuBrF, CuFI, CuClBr, CuClI, CuBrI, AgFCl, AgFBr, AgFI, AgClBr, AgClI, AgBrI, AuFCl, AuFBr, AuFI, AuClBr, AuClI, AuBrI, CuFClBr, CuFClI, CuFBrI, CuIBrCl, AgFClBr, AgFClI, AgFBrI, AgClBrI, AuFClBr, AuFClI, AuFBrI, or AuClBrI, which may contain at least one.

In addition, one or more p-type local doped layers may be formed on the barrier layer.

In this case, the p-type local doping layer formed on the barrier layer is preferably formed adjacent to the quantum well layer.

In addition, the p-type local doping layer formed on the barrier layer is preferably spaced apart from the electron blocking layer by more than 10nm.

When the p-type local doping layer is formed in the barrier layer, as in the semiconductor light emitting device according to the present invention, the luminous efficiency can be improved by reducing the internal electric field of the active layer due to the spontaneous polarization caused by the piezo effect.

In addition, by forming the p-type local doping layer on the electron blocking layer, it is possible to effectively inject holes while providing an effective blocking effect on electrons. In the p-type local doping layer, the energy level of the holes formed therein increases the tunneling probability of the holes injected from the p-type electrode, thereby increasing the internal quantum efficiency, thereby improving luminous efficiency.

In addition, when the p-type local doping layer is further formed on the thus formed electron blocking layer, the luminous efficiency may be further improved.

In addition, when the p-type local doping layer of the barrier layer is formed adjacent to the active layer, the distance between the electron blocking layer is maximized so that electrons and holes are spaced apart from the barrier layer as much as possible, thereby effectively increasing the Auger recombination probability. Can be reduced.

1 is a diagram schematically showing a band structure of a conventional semiconductor light emitting device.

2 is a diagram schematically showing a band structure of a semiconductor light emitting device according to an exemplary embodiment of the present invention.

3 is a diagram schematically showing a band structure of a semiconductor light emitting device according to another exemplary embodiment of the present invention.

4 is a diagram schematically showing a band structure of a semiconductor light emitting device according to another exemplary embodiment of the present invention.

As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described in the specification, and that one or more other features It should be understood that it does not exclude in advance the possibility of the presence or addition of numbers, steps, actions, components, parts or combinations thereof.

In the present invention, the term "formed on" or "formed on" a film (or layer) means that in addition to being directly formed to be in contact, another film or other layer may be formed therebetween, "Formed directly" on a layer means that no other layer is interposed therebetween.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art.

Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a diagram schematically showing a band structure of a semiconductor light emitting device according to an exemplary embodiment of the present invention.

2, a semiconductor light emitting device 100 according to an exemplary embodiment of the present invention may include an n-type semiconductor layer 110, a quantum well layer 120, a barrier layer 130, and a p-type semiconductor layer. And 150. Although not shown, the semiconductor light emitting device 100 may further include the electron blocking layer 140 illustrated in FIG. 1. The n-type semiconductor layer 110, the quantum well layer 120, the barrier layer 130, the p-type semiconductor layer 150, and the electron blocking layer 140 include an I-VII compound semiconductor. do. In more detail, the n-type semiconductor layer 110, the quantum well layer 120, the barrier layer 130, the p-type semiconductor layer 150, and the electron blocking layer 140 are CuFCl and CuBrF, respectively. , CuFI, CuClBr, CuClI, CuBrI, AgFCl, AgFBr, AgFI, AgClBr, AgClI, AgBrI, AuFCl, AuFBr, AuFI, AuClBr, AuClI, AuBrI, CuFClBr, CuFClI, CuFBrI, CuIBrCl, AgFCrB AgICI At least one of AuFClI, AuFBrI, or AuClBrI may be included.

Among these materials, the band gap of the quantum well layer 120 is selected to be the smallest, and the band of the n-type semiconductor layer 110, the barrier layer 130, and the p-type semiconductor layer 150 is selected. The gap may be formed by selecting a material larger than the quantum well layer 120. In addition, the n-type semiconductor layer 110 may add n-type impurities (eg, zinc (Zn), magnesium (Mg), or the like), and the p-type semiconductor layer 150 may be p-type. It can be formed by adding impurities (eg, oxygen (O), sulfur (S), selenium (Se), or the like).

The n-type semiconductor layer 110 is formed on a substrate (not shown), molecular beam epitaxy (MBE), metal organic chemical vapor deposition (MOCVD), hydride vapor phase epitaxy (HVPE), atomic layer epitaxy (ALE), and / Or else similar. For example, the substrate may be a silicon (Si) substrate. As shown in Table 1 below of the silicon substrate, the lattice constant is similar to that of the copper blend I-VII compound semiconductor, thereby enabling a good thin film formation. More preferably, the n-type semiconductor layer 110 may be formed on the (111) surface of the silicon substrate.

	Lattice Constant (Angstrom)	Bandgap energy (eV)
Si	5.43	1.1 (indirect)
CuCl	5.42	3.399
CuBr	5.68	2.91
CuI	6.05	2.95

Relatively inexpensive silicon substrates may also be used compared to more expensive conventional substrate materials such as sapphire, since their lattice constants are close to those of the I-V compound semiconductors, although they have different crystal structures. For example, silicon is known to have a diamond structure, while CuCl has a diamond structure. In particular, the (111) face of the silicon substrate may be used to fabricate the semiconductor light emitting device 100 as it may be suitable for the crystal structure of CuCl, which may be stacked on the substrate. In other embodiments, the substrate may be used with sapphire, bulk gallium nitride, or the like.

The quantum well layer 120 may be formed through the n-, through molecular beam epitaxy (MBE), metal organic chemical vapor deposition (MOCVD), hydride vapor phase epitaxy (HVPE), atomic layer epitaxy (ALE), and / or the like. The semiconductor layer 110 may be formed on the semiconductor semiconductor layer 110.

The barrier layer 130 may be formed through the quantum well layer through molecular beam epitaxy (MBE), metal organic chemical vapor deposition (MOCVD), hydride vapor phase epitaxy (HVPE), atomic layer epitaxy (ALE), and / or the like. 120 may be formed on top.

The p-type semiconductor layer 150 may be formed through molecular beam epitaxy (MBE), metal organic chemical vapor deposition (MOCVD), hydride vapor phase epitaxy (HVPE), atomic layer epitaxy (ALE), and / or the like. It may be formed on the barrier layer 130.

The quantum well layer 120 including the I-V compound semiconductor may have a relatively large exciton binding energy, for example, an exciton binding energy at least twice as large as those of group III nitride. This can improve quantum efficiency. In particular, I-VIII compound semiconductors with large exciton binding energies may be suitable for strong optical transitions, for example, which are desirable in light emitting devices that emit light in the blue region of the visible spectrum. The exciton binding energy is a measure of the interaction of holes and electrons, with opposite charges, and may be used to predict the strength of the hole-electron recombination process. For example, CuBr is known to have an exciton binding energy of about 108 meV, which is higher than the exciton binding energy of ZnO. As a result, the I-VIII compound semiconductor based light emitting devices have greater optical gain than conventional wide bandgap semiconductors such as group III nitride or ZnO based light emitting devices.

Meanwhile, at least one p-type local doping layer 131 is formed on the barrier layer 130. The p-type local doping layer 131 is a thin film single crystal having an atomic unit thickness to include the p-type impurities described above.

The p-type local doping layer 131 may be formed adjacent to the quantum well layer 120. When the barrier layer 130 is formed adjacent to the quantum well layer 120, the barrier height of the well wall 120 is increased to transfer electrons from the quantum well layer 120 to the barrier layer 130. In addition, the p-type local doping layer 131 may increase the internal quantum efficiency by reducing the internal electric field in the quantum well layer 120 due to the piezo effect and spontaneous polarization.

3 is a diagram schematically showing a band structure of a semiconductor light emitting device according to another exemplary embodiment of the present invention. In the description of FIG. 3, the overlapping part of the description of the embodiment with reference to FIG. 2 is omitted.

Referring to FIG. 3, a semiconductor light emitting device 100 according to another exemplary embodiment of the present invention may include an n-type semiconductor layer 110, a quantum well layer 120, a barrier layer 130, and an electron blocking layer 140. ) And the p-type semiconductor layer 150.

The n-type semiconductor layer 110 may be formed on a substrate (not shown).

The quantum well layer 120 is formed on the n-type semiconductor layer 110. The barrier layer 130 is formed on the quantum well layer 120.

The electron blocking layer 140 is formed on the barrier layer 130. The p-type semiconductor layer 150 is formed on the electron blocking layer 140.

Meanwhile, at least one p-type local doping layer 141 is formed on the electron blocking layer 140. As described above, when the p-type local doping layer 141 is formed on the electron blocking layer 141, the P-type local doping layer 141 is provided with an effective blocking effect on electrons, and enables effective transmission of holes. That is, the energy level of the holes formed in the p-type local doping layer 141 increases the tunneling probability of the holes injected from the p-type electrode, thereby increasing the internal quantum efficiency.

4 is a diagram schematically showing a band structure of a semiconductor light emitting device according to another exemplary embodiment of the present invention. The semiconductor light emitting device shown in FIG. 4 additionally forms the p-type local doping layer 131 shown in FIG. 2 in the semiconductor light emitting device shown in FIG. However, if the p-type local doping layer 131 is formed on the barrier layer 130 and the p-type local doping layer 141 is formed on the electron blocking layer 140 as described above, not only the foregoing effects, but also the A synergistic effect can be expected. The foregoing descriptions and repeated descriptions are omitted.

4, a semiconductor light emitting device 100 according to another exemplary embodiment of the present invention may include an n-type semiconductor layer 110, a quantum well layer 120, a barrier layer 130, and an electron blocking layer 140. ) And the p-type semiconductor layer 150. At least one p-type local doping layer 131 is formed on the barrier layer 130. The p-type local doping layer 131 may be formed adjacent to the quantum well layer 120. In addition, the p-type local doping layer 131 formed on the barrier layer 130 may be spaced apart from the electron blocking layer 140 by 10 nm or more. In addition, at least one p-type local doping layer 141 is formed on the electron blocking layer 140.

The potential formed by local doping is given by Equation 1 below. [D. Ahn, Phys. Rev. 48, 7981 (1993).

Where P _S is the surface charge density of the local doped layer. The energy level of the hole can be obtained from Schrödinger's equation as shown in Equation 2 below.

here

to be.

The structure that can separate the maximum value of the electron and hole distribution in order to reduce the Auger recombination is shown in FIG.

Since the p-type local doping layer 131 formed on the barrier layer 130 serves to cancel the internal electric field, the p-type local doping layer 131 is close to the quantum well layer 120 (just after the last barrier layer), but the electron blocking layer 140 Place at a distance (10 nm or more). Due to the electron blocking layer 140, the electrons in the p-type semiconductor layer 150 may have a maximum density immediately before the electron blocking layer 140. On the other hand, due to the p-type local doping layer 131 formed on the barrier layer 130, the maximum hole distribution is due to the p-type local doping layer 131 and the electron blocking layer formed immediately after the last barrier of the quantum well layer 120. It is expected to be formed in the p-type local doping layer 141 formed at 140 to effectively reduce the Auger recombination probability.

In the detailed description of the present invention described above with reference to the preferred embodiments of the present invention, those skilled in the art or those skilled in the art having ordinary skill in the art will be described in the claims to be described later It will be understood that various modifications and variations can be made in the present invention without departing from the scope of the present invention.

Claims (12)

1. An n-type semiconductor layer comprising an I-VII compound semiconductor;

   A quantum well layer formed on the n-type semiconductor layer and including an I-VII compound semiconductor;

   A barrier layer formed on the quantum well layer and including an I-VII compound semiconductor; And

   A p-type semiconductor layer formed on the barrier layer and including an I-VII compound semiconductor,

   At least one p-type local doped layer is formed in the barrier layer.
2. The method of claim 1,

   And the p-type local doped layer is formed adjacent to the quantum well layer.
3. The method of claim 1,

   The n-type semiconductor layer, the quantum well layer, the barrier layer and the p-type semiconductor layer are CuFCl, CuBrF, CuFI, CuClBr, CuClI, CuBrI, AgFCl, AgFBr, AgFI, AgClBr, AgClI, AgBrI, AuFCl, A device comprising at least one semiconductor light emitting device comprising at least one of AuFBr, AuFI, AuClBr, AuClI, AuBrI, CuFClBr, CuFClI, CuFBrI, CuIBrCl, AgFClBr, AgFClI, AgFBrI, AgClBrI, AuFClBr, AuFClI, AuFBrI, or AuClBrI.
4. The method of claim 1,

   And at least one electron blocking layer formed between the barrier layer and the p-type semiconductor layer.
5. The method of claim 4, wherein

   And the p-type local doped layer formed on the barrier layer is spaced apart from the electron blocking layer by 10 nm or more.
6. The method of claim 4, wherein

   At least one p-type local doped layer is formed in the electron blocking layer.
7. The method of claim 4, wherein

   The electron blocking layer is CuFCl, CuBrF, CuFI, CuClBr, CuClI, CuBrI, AgFCl, AgFBr, AgFI, AgClBr, AgClI, AgBrI, AuFCl, AuFBr, AuFI, AuClBr, AuClI, AuBrI, CuFClBr, CuBrIFC, CuBBI And at least one of AgFClI, AgFBrI, AgClBrI, AuFClBr, AuFClI, AuFBrI, or AuClBrI.
8. Board;

   An n-type semiconductor layer formed on the substrate and comprising an I-VII compound semiconductor;

   A quantum well layer formed on the n-type semiconductor layer and including an I-VII compound semiconductor;

   A barrier layer formed on the quantum well layer and including an I-VII compound semiconductor;

   At least one electron blocking layer formed on the barrier layer and including an I-VII compound semiconductor; And

   A p-type semiconductor layer formed on the electron blocking layer and including an I-VII compound semiconductor,

   At least one p-type local doped layer is formed in the electron blocking layer.
9. The method of claim 8,

   The n-type semiconductor layer, the quantum well layer, the barrier layer and the p-type semiconductor layer are CuFCl, CuBrF, CuFI, CuClBr, CuClI, CuBrI, AgFCl, AgFBr, AgFI, AgClBr, AgClI, AgBrI, AuFCl, A device comprising at least one semiconductor light emitting device comprising at least one of AuFBr, AuFI, AuClBr, AuClI, AuBrI, CuFClBr, CuFClI, CuFBrI, CuIBrCl, AgFClBr, AgFClI, AgFBrI, AgClBrI, AuFClBr, AuFClI, AuFBrI, or AuClBrI.
10. The method of claim 8,

    At least one p-type local doped layer is formed in the barrier layer.
11. The method of claim 10,

    And the p-type local doped layer formed in the barrier layer is formed adjacent to the quantum well layer.
12. The method of claim 10,

    And the p-type local doped layer formed on the barrier layer is spaced apart from the electron blocking layer by 10 nm or more.

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