JP5100180B2 - Light emitting device and manufacturing method - Google Patents

Description

  The present invention relates to a light emitting device and a method for manufacturing the same.

  In recent years, research and development of light-emitting elements that operate with direct current have been actively conducted. In particular, gallium nitride (GaN) is a practical semiconductor material used for light-emitting elements such as blue-light emitting diodes (Blue-LEDs) and ultraviolet-light emitting diodes (UV-LEDs). ), Indium nitride / gallium mixed crystal (InGaN), aluminum nitride / gallium mixed crystal (AlGaN), or indium nitride / aluminum / gallium mixed crystal (InAlGaN).

  Conventionally, such a Group 3 nitride compound semiconductor has been produced as a single crystal thin film by growing it on a substrate using MOCVD (Metal Organic Chemical Vapor Deposition).

  However, when manufacturing a light emitting device by MOCVD, the substrate to be used needs to have a crystal lattice constant substantially equal to the compound semiconductor to be grown and have excellent heat resistance. That is, there is a problem that the material and size of the substrate are restricted.

For example, when a Group 3 nitride compound semiconductor is grown, a crystalline sapphire (α-Al ₂ O ₃ ) substrate is mainly used. This sapphire has a crystal lattice constant almost equal to that of a Group 3 nitride compound semiconductor, especially gallium nitride, and has excellent heat resistance, and is a material suitable as a substrate for MOCVD. However, when a sapphire substrate is used, it is necessary to grow on the c-plane, so that there is a problem in the workability and formability of the substrate and the material cost is increased.

  In addition, since it is difficult to form a thin film with a uniform film thickness on the entire surface of the substrate, it is not possible to use a substrate with a large area, and currently it is about 20 cm × 20 cm at the maximum, and productivity is low. There was also a problem.

  Furthermore, since the light-emitting element has a multilayer structure including a light-emitting layer (also referred to as an active layer) and an electron / hole carrier transport layer, a compound semiconductor is used so that crystal lattice distortion does not occur at the bonding surface of each semiconductor layer. Must be epitaxially grown. The reason for this is that when crystal lattice distortion occurs, crystal lattice defects such as dislocations occur in the vicinity of the junction surface of each semiconductor layer, resulting in a decrease in luminous efficiency. That is, it is necessary to precisely control the crystal system and the lattice constant of each semiconductor layer, and there is a problem that it is extremely difficult to set and control the crystal growth conditions and it is difficult to manufacture.

  Therefore, in order to realize a light-emitting device capable of surface emission, a particle layer in which particles are bonded by sandwiching between a hole transport layer and an electron transport layer is sandwiched, and a voltage is applied between the hole transport layer and the electron transport layer. However, a method for enabling surface emission has been attempted (for example, see Patent Document 1).

JP 2001-210865A

  However, in the method of manufacturing a light-emitting element as in Patent Document 1 and the structure of the light-emitting element obtained thereby, it is necessary to combine particles by firing, so a material having a low vapor pressure or a sublimable material such as GaN is used. When using, there is a problem that it cannot be used. In addition, since the space between the particles is a cavity, it is easy to generate a leakage current.

  Accordingly, in order to solve such problems, an object of the present invention is to realize a light emitting element capable of realizing surface emission in a large area and suppressing power consumption due to leakage current, and a method for manufacturing the same. Is to provide.

A light emitting device according to the present invention is sandwiched between an electron transport layer, a hole transport layer facing the electron transport layer and spaced apart, and the electron transport layer and the hole transport layer. A light emitting layer having a layer made of a plurality of semiconductor fine particles, a first electrode provided facing the electron transport layer and electrically connected thereto, provided facing the hole transport layer, and electrically A light-emitting element having a multilayer structure in which connected second electrodes are sequentially stacked, and the semiconductor fine particles constituting the light-emitting layer have an n-type inner core and an n-type portion in part, An outer shell partly formed as a p-type part, wherein a pn junction is formed at an interface between the p-type part of the outer shell and the n-type part of the inner core, and the p-type of the outer shell. A portion of the portion is in contact with the hole transport layer and the n-type portion of the outer shell Parts is characterized in that it is arranged so as to be in contact with the electron transport layer.

  Further, the light emitting layer may have a single particle layer of the semiconductor fine particles. Furthermore, the light emitting layer may further include a dielectric that fills a gap between the semiconductor fine particles.

  The average particle diameter of the semiconductor fine particles is preferably larger than the average distance between the electron transport layer and the hole transport layer.

  The semiconductor particles may include GaN microcrystals. The average particle size of the semiconductor fine particles may be in the range of 1 to 100 μm.

A method for manufacturing a light emitting device according to the present invention includes an electron transport layer, a hole transport layer facing the electron transport layer and spaced apart, and sandwiched between the electron transport layer and the hole transport layer. A light emitting layer having a layer made of a plurality of semiconductor fine particles, a first electrode provided facing the electron transport layer and electrically connected, and facing the hole transport layer; A method of manufacturing a light-emitting device having a multilayer structure in which second electrodes connected in series are sequentially stacked , wherein the semiconductor fine particles constituting the light-emitting layer have an n-type inner core and partly an n-type A structure in which a pn junction is formed at an interface between the p-type part of the outer shell and the n-type part of the inner core, and a substrate having a part remaining and a p-type part of the outer shell. Forming a first electron transport layer on the first electron transport layer; A second electron transport layer having fluidity is formed on the layer, and then the semiconductor fine particles are formed on the second electron transport layer, and a part of the n-type portion of the outer shell is formed on the second electron transport layer. After forming the light emitting layer so as to be in contact with each other, a hole transport layer is formed on the semiconductor fine particle so that a part of the p-type portion of the outer shell is in contact with the hole transport layer.

A step of embedding a dielectric in the gap between the semiconductor fine particles;
And removing the dielectric so that the upper part of the semiconductor fine particles is exposed.

  Furthermore, semiconductor fine particles containing GaN may be used as the semiconductor fine particles.

  According to the present invention, it is possible to manufacture a light emitting device capable of surface light emission in a large area at a low cost.

  A light emitting device and a method for manufacturing the same according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the drawings, substantially the same members are denoted by the same reference numerals, and description thereof is omitted.

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view showing a configuration of a light-emitting element 10 according to Embodiment 1 of the present invention. FIG. 2 is an enlarged cross-sectional view showing the relationship among the electron transport layer 3, the light emitting layer 4, and the hole transport layer 5 of FIG. The light emitting element 10 includes a lower electrode 2, an electron transport layer 3, a light emitting layer 4 having a single particle layer of semiconductor fine particles 11 including semiconductor microcrystals, a hole transport layer 5, and an upper electrode 6 in this order. It has a multi-layered structure. In addition, the electron transport layer 3 and the hole transport layer 5 face each other and are spaced apart. Furthermore, the light emitting layer 4 has a single particle layer of the semiconductor fine particles 11 sandwiched between the electron transport layer 3 and the hole transport layer 5. The semiconductor fine particle 11 has a p-type portion 13a and an n-type portion 13b, and has a pn junction inside the particle. Further, a part of the p-type portion 13 a of each particle 11 is in contact with the hole transport layer 5, and a part of the n-type portion 13 b is in contact with the electron transport layer 3. The average particle diameter R of the semiconductor fine particles 11 is larger than the average distance d between the electron transport layer 3 and the hole transport layer 5 (R> d). The lower electrode 2 is electrically connected to the electron transport layer 3. The upper electrode 6 is electrically connected to the hole transport layer 5. The light emitting layer 4 further includes a dielectric 12 that fills the gap between the semiconductor fine particles 11. This dielectric 12 can reduce the leakage current. The dielectric 12 is not necessarily required. For example, the dielectric 12 may not be used as long as the electron transport layer 3 and the hole transport layer 5 can be separated at a predetermined interval by an external support or the like. . The light emitting element 10 can emit light by applying a voltage by a power source 7 connected between the upper electrode 6 and the lower electrode 2.

  In the light emitting element 10, the light emitting layer 4 can be formed as a single particle layer of the semiconductor fine particles 11, and thus can be manufactured at a lower cost than the case where the light emitting element 10 is formed of a thin film. Further, since the semiconductor fine particles 11 are directly sandwiched between the electron transport layer 3 and the hole transport layer 5 without using a binder and are electrically connected to the respective layers 3 and 5, Electron / hole carrier injection efficiency can be improved. Thereby, the luminous efficiency of the light emitting element 10 can be increased. Further, since a part of the p-type portion 13a of each particle is in contact with the hole transport layer 5 and a part of the n-type portion 13b is in contact with the electron transport layer 3, holes and electrons are efficiently introduced into the semiconductor fine particles 11. Introduced. Thereby, light can be efficiently emitted at the pn junction inside each particle 11.

Hereinafter, each component of the light emitting element 10 will be described.
<Board>
Examples of the substrate 1 include a glass substrate, a ceramic substrate, a sapphire substrate, a boron nitride (BN) substrate, an aluminum nitride substrate, a gallium nitride substrate, an aluminum nitride / gallium substrate, an indium nitride / gallium substrate, a silicon carbide (SiC) substrate, A silicon (Si) substrate, a metal substrate, or a resin substrate made of polycarbonate resin, polyethylene terephthalate resin, polyester resin, epoxy resin, acrylic resin, ABS (acrylonitrile-butadiene-styrene copolymer) resin, or the like can be used.

  Note that in the case of a configuration in which light is not extracted from the substrate 1 side, the above-described light transmittance is unnecessary, and a material that does not have light transmittance can also be used.

<Electrode>
There are a lower electrode 2 and an upper electrode 6 as electrodes. For example, the electrode on the side from which light is extracted may be a transparent electrode and the other electrode may be a back electrode. The materials of the electrodes 2 and 6 are limited depending on whether or not they are on the light extraction side. Both electrodes 2 and 6 may be transparent electrodes. Therefore, the lower electrode 2 and the upper electrode 6 will be described not with respect to their arrangement but with each of a case where they are used as transparent electrodes and a case where they are used as back electrodes.

First, the case where it uses as a transparent electrode is demonstrated. The material of the transparent electrode is not particularly limited as long as it has light transmittance so that light emitted in the light emitting layer 4 can be extracted to the outside, and preferably has a high transmittance in the visible light region. Moreover, it is preferable that it is low resistance as an electrode, and also it is preferable that it is excellent in adhesiveness with the board | substrate 1 and the light emitting layer 3. FIG. As a material for the transparent electrode, a metal oxide mainly composed of ITO (In ₂ O ₃ doped with SnO ₂ , also referred to as indium tin oxide), InZnO, ZnO, SnO ₂ or the like is preferable. Pt, Au, Pd, Ag, Ni, Cu, Al, Ru, Rh, Ir, etc., or conductive polymers such as polyaniline, polypyrrole, PEDOT / PSS, polythiophene, etc. It is not limited to. These transparent electrodes can be formed by a film forming method such as a sputtering method, an electron beam evaporation method, or an ion plating method for the purpose of improving the transparency or reducing the resistivity. Further, after film formation, surface treatment such as plasma treatment may be performed for the purpose of resistivity control. The film thickness of the transparent electrode is determined from the required sheet resistance value and visible light transmittance.

The carrier concentration of the transparent electrode is desirably in the range of 1E17 to 1E22 cm ⁻³ . In order to obtain performance as a transparent electrode, the volume resistivity of the transparent electrode is preferably 1E-3 Ω · cm or less, and the transmittance is preferably 75% or more at a wavelength of 380 to 780 nm. The refractive index of the transparent electrode is preferably 1.85 to 1.95. Furthermore, when the film thickness of the transparent electrode is 30 nm or less, a dense and stable film can be realized.

Further, the case of using as a back electrode will be described. Any generally known conductive material can be applied to the back electrode. Furthermore, it is preferable that the adhesiveness with the adjacent layers 3 and 5 is excellent. Suitable examples include, for example, metal oxides such as ITO, InZnO, ZnO, SnO ₂ , Pt, Au, Pd, Ag, Ni, Cu, Al, Ru, Rh, Ir, Cr, Mo, W, Ta, Metals such as Nb, laminated structures thereof, conductive polymers such as polyaniline, polypyrrole, PEDOT [poly (3,4-ethylenedioxythiophene)] / PSS (polystyrene sulfonic acid), or conductive carbon Can be used.

  Next, the electron transport layer 3 and the hole transport layer 5 will be described. The electron transport layer 3 and the hole transport layer 5 face each other and are spaced apart.

<Electron transport layer>
The electron transport layer 3 is made of a nitride of a Group 3B element to which an n-type impurity such as silicon (Si) is added. The electron transport layer 3 may have any form such as a single crystal body, a polycrystal body, an amorphous body, a fine particle body, an organic material, a composite thereof, or a laminated film.

  Further, the electron transport layer 3 preferably has a larger forbidden band energy than the semiconductor fine particles 11 including the semiconductor microcrystals constituting the light emitting layer 4. Thereby, the electron transport layer 3 can function as a carrier confinement and cladding layer for the semiconductor fine particles 11. Further, the wavelength of light emitted from the semiconductor fine particles 11 is longer than the absorption edge wavelength of the electron transport layer 3, and the light emitted from the semiconductor fine particles 11 is transmitted through the electron transport layer 3 without being attenuated. Therefore, light can be extracted from the substrate 1 side, and the light extraction efficiency can be increased.

<Hole transport layer>
The hole transport layer 5 is made of, for example, a nitride of a group 3B element to which a p-type impurity such as magnesium (Mg) is added. The hole transport layer 5 may have any form such as a single crystal body, a polycrystal body, an amorphous body, a fine particle body, an organic substance, a composite thereof, or a laminated film.

  The hole transport layer 5 preferably has a larger forbidden band energy than the semiconductor fine particles 11 containing the semiconductor microcrystals constituting the light emitting layer 4. Thereby, like the electron transport layer 3, the hole transport layer 5 can function as a carrier confinement and cladding layer for the semiconductor fine particles 11. Further, the wavelength of light emitted from the semiconductor fine particles 11 is longer than the absorption edge wavelength of the hole transport layer 5, and the light emitted from the semiconductor fine particles 11 including semiconductor microcrystals passes through the hole transport layer 5. Since the light is transmitted without being attenuated, light can be extracted from the hole transport layer 5 side, and the light extraction efficiency can be increased.

<Light emitting layer>
The light emitting layer 4 has a layer made of semiconductor fine particles 11 sandwiched between the electron transport layer 3 and the hole transport layer 5. In addition, as described above, the dielectric 12 that fills the gap between the semiconductor fine particles 11 may be further included. By using the dielectric 12, the leakage current can be reduced. The layer composed of the semiconductor fine particles 11 constituting the light emitting layer 4 is preferably formed as a single particle layer between the electron transport layer 3 and the hole transport layer 5. Further, as the semiconductor fine particles 11, those having an average particle diameter R larger than the average interplanar distance d between the electron transport layer 3 and the hole transport layer 5 are used (relational formula: R> d). As a result, the electron transport layer 3 and the hole transport layer 5 are opposed to each other and separated from each other by a predetermined interval, and the electrical transport between the electron transport layer 3 and the hole transport layer 5 via each particle of the semiconductor fine particles 11 is performed. Connection can be made. In addition, the average particle diameter R of this semiconductor fine particle 11 should just be in the range of 1-100 micrometers.

<Semiconductor fine particles>
4A and 4B are schematic cross-sectional views showing the internal structure of the semiconductor fine particles 11 and 11a . A semiconductor fine particle 11 shown in FIG. 4A includes a p-type portion 13a at the upper portion of the particle and an n-type portion 13b at the lower portion, and has a pn junction at the interface between the p-type portion 13a and the n-type portion 13b. Further , as shown in FIG. 4B , the semiconductor fine particle 11a of the present invention has a doped type that is different between the inner core and a part of the outer shell using semiconductor materials having different doping characteristics between the inner core and the outer shell. . This semiconductor fine particle 11a has an n-type inner core 13c that is difficult to be doped, and an outer shell that is easily doped, part of the original n-type part 13b remains, and part of which becomes a p-type part 13a. A pn junction is formed at the interface between the outer shell p-type doped portion 13a and the inner core n-type portion 13c. In this case, by leaving the n-type portion 13b in the lower part of the outer shell, electrical connection with the electron transport layer 3 can be ensured from the n-type portion 13c of the inner core through the n-type portion 13b.

  The semiconductor fine particles 11 containing the semiconductor microcrystals only need to be at least partially composed of microcrystals. For example, the semiconductor fine particles 11 may contain particles other than the semiconductor microcrystals. Further, for example, fine particles in which a coating layer or the like is provided on the microcrystal may be included. Further, the semiconductor fine particles 11 themselves may be single crystals. Here, the microcrystal is a fine particle made of single crystal or polycrystal. Further, the semiconductor fine particles 11 emit forbidden band transition light emission (light emission due to forbidden band transition) or donor-acceptor pair light emission (light emission due to transition between donor-acceptor levels). That is, the particle 11 has a forbidden band transition emission function or a donor-acceptor pair emission function.

As the semiconductor fine particles 11, for example, a group III-V compound semiconductor, specifically, GaAs, InP, etc., oxides or nitrides, such as zinc (Zn), titanium (Ti), and iron (Fe) are used. Of these, oxides containing at least one of them, nitrides of Group 3B elements, and the like are preferable. Specifically, zinc oxide, titanium oxide (TiO ₂ ), iron oxide (Fe ₂ O ₃ or FeO), zinc oxide / titanium oxide (ZnO · TiO ₂ ) mixed crystal, zinc oxide · iron oxide (ZnO · Fe ₂₎ O ₃ ) mixed crystal or titanium oxide / iron oxide (TiO ₂ · Fe ₂ O ₃ ) mixed crystal, gallium nitride, indium nitride, indium nitride / gallium mixed crystal, aluminum nitride / gallium mixed crystal or indium nitride / aluminum / Examples include gallium mixed crystals.

For example, when the semiconductor fine particles 11 are configured to include microcrystals made of zinc oxide, titanium oxide, or iron oxide, the hole transport layer 5 is made of boron nitride, aluminum nitride, gallium nitride, aluminum nitride / gallium mixed. Preferably, it is composed of crystals. The band gap energy of the semiconductor fine particles 11 is 3.2 eV for zinc oxide, 3.0 eV for titanium oxide, 3.1 eV for iron oxide (Fe ₂ O ₃ ), 6.2 eV for boron nitride, and 6.2 eV for aluminum nitride. The voltage is 6.1 eV and 3.4 eV for gallium nitride. In the case of a mixed crystal, it varies depending on the composition.

<Dielectric material>
For the dielectric 12, a low dielectric constant material or a high dielectric constant material can be used as necessary. In the case of a low dielectric constant material, specifically, a metal oxide such as SiO ₂ , Al ₂ O ₃ , Y ₂ O ₃ , BaTa ₂ O ₆ , Ta ₂ O _5, a nitride such as Si ₃ N ₄ , SiON, etc. The oxynitride can be used. In the case of a high dielectric constant material, specifically, a ceramic material having a perovskite structure is preferable, and more specifically, PbNbO ₃ , BaTiO ₃ , SrTiO ₃ , PbTiO ₃ , (Sr, Ca) TiO _3, or the like is used. Can do. By filling the gap between the semiconductor fine particles 11 with the dielectric 12, it is possible to make it difficult for leakage current to occur.

<Manufacturing method>
FIGS. 3A to 3I are schematic cross-sectional views illustrating each step of the method for manufacturing the light emitting element 10 according to the first embodiment.
(A) First, the lower electrode 2 is patterned on the substrate 1, and a first electron transport layer 3a is formed on the patterned lower electrode 2 (FIG. 3A).
(B) Next, a liquid second electron transport layer 3b having fluidity is formed on the first electron transport layer 3a by coating (FIG. 3B). The second electron transport layer 3b is formed by applying a liquid. The film thickness d1 of the second electron transport layer 3b is formed to be smaller than the diameter R of the semiconductor fine particles 11 including semiconductor microcrystals to be formed later (relational expression: d1 <R). The first electron transport layer 3a and the second electron transport layer 3b may be the same material or different materials. Further, the second electron transport layer 3b is not limited to the one having fluidity, and the second electron transport layer 3b may be one having adhesiveness capable of adhering the semiconductor fine particles 11 or one in which the semiconductor fine particles 11 are partially embedded. .

(C) Next, on the second electron transport layer 3b having fluidity, the light emitting layer 4 composed of one particle layer of the semiconductor fine particles 11 including semiconductor microcrystals is formed (FIG. 3C). As described above, the film thickness d1 of the second electron transport layer 3b is thinner than the diameter R of the semiconductor fine particles 11. Therefore, by spraying the semiconductor fine particles 11 on the second electron transport layer 3b, the semiconductor fine particles 11 are adhered to the second electron transport layer 3b exactly one particle at a time, and excess particles are removed. One particle layer of the semiconductor fine particles 11 is formed. As a result, the electrical connection between the semiconductor fine particles 11 and the second electron transport layer 3b can be ensured, and the dielectric 12 formed thereafter becomes between the semiconductor fine particles 11 and the first electron transport layer 3a. Intrusion can be suppressed. The semiconductor fine particles 11 may be in contact only with the upper part of the second electron transport layer 3b. Alternatively, the semiconductor fine particles 11 may be embedded in the second electron transport layer 3b and in contact with the first electron transport layer 3a. The first electron transport layer 3a and the second electron transport layer 3b constitute the electron transport layer 3. The light emitting layer 4 made of the semiconductor fine particles 11 is not limited to the spraying method, and may be formed by, for example, coating.
(D) A dielectric film 12 is formed so as to fill the gaps between the particles 11 containing semiconductor microcrystals (FIG. 3D).
(E) The excess dielectric film is removed so that the upper portions of the particles 11 containing semiconductor microcrystals are exposed (FIG. 3E).
(F) A p-type doped material 23 is formed on the particles (FIG. 3 (f)). For the p-type doped material 23, for example, a material such as Mg is used.
(G) A p-type doped portion 13a is formed on the top of the particles 11 containing semiconductor microcrystals by a method such as heat treatment, and then the unnecessary p-type doped material 23 is removed (FIG. 3G). .
(H) The hole transport layer 5 is formed on the semiconductor fine particles 11 (FIG. 3 (h)).
(I) An upper electrode 6 is formed on the hole transport layer 5 (FIG. 3 (i)).
Thus, the light emitting element 10 is formed.

  In this manufacturing method, the single particle layer of the semiconductor fine particles 11 is formed on the electron transport layer 3, but this is not the only case, and conversely, the single particle layer of the semiconductor fine particles 11 is formed on the hole transport layer 5. It may be provided.

  Moreover, although the fluid 2nd electron carrying layer 3b was used in the said manufacturing method, the 2nd electron carrying layer 3b is not necessarily used. The second electron transport layer 3b having fluidity is used for bonding the semiconductor fine particles 11 in order to form a single particle layer of the semiconductor fine particles 11 thereon. Therefore, when the first electron transport layer 3a has adhesiveness on the surface thereof, it is not necessary to use the fluid second electron transport layer 3b. Further, even when the first electron transport layer 3a does not have adhesiveness on the surface, when one particle layer of the semiconductor fine particles 11 is formed thereafter, the semiconductor fine particles 11 and the first electron transport layer 3a The second electron transport layer 3b need not be used as long as the electrical connection can be secured.

Further, in the above manufacturing method, the case of FIG. 4A has been described as the semiconductor fine particle 11 , but the present invention is not limited to this, and for example, the semiconductor fine particle 11 a having the structure shown in FIG. it can.

FIGS. 5A to 5C are schematic cross-sectional views showing the core process of the manufacturing method for forming the structure of the semiconductor fine particles 11a shown in FIG. 4B.
(A) Semiconductor fine particles 11a each having an inner core 13c made of an n-type semiconductor and an outer shell 13b made of an n-type semiconductor are prepared (FIG. 5A). The inner core and the outer shell have different doping characteristics, and the inner core is not easily p-type doped and the outer shell is easily p-type doped.
(B) Doping is performed from above the particles 11 with, for example, the p-type doping material 23 (FIG. 5B).
(C) In this semiconductor fine particle 11a , since the inner core is not easily p-type doped, it remains as the n-type portion 13c, and the outer shell is easily p-type doped. A p-type portion 13a is formed over the portion (FIG. 5A). In this way, a pn junction is formed at the interface between the p-type doped portion 13a of the outer shell and the n-type portion 13c of the inner core.
Thus, the semiconductor fine particles 11a having the structure shown in FIG. 4B are formed. In this case, since the n-type portion 13b remains in the lower part of the outer shell, electrical connection with the electron transport layer 3 can be ensured from the n-type portion 13c of the inner core through the n-type portion 13b.

  According to the present invention, it is possible to manufacture a light emitting device capable of surface light emission in a large area at a low cost.

It is a schematic sectional drawing which shows the structure of the light emitting element which concerns on Embodiment 1 of this invention. It is an expanded sectional view which shows the relationship between the electron carrying layer of FIG. 1, a light emitting layer, and a hole transport layer. FIG. 5 is a schematic cross-sectional view showing one step in the method for manufacturing the light emitting element according to Embodiment 1. FIG. 5 is a schematic cross-sectional view showing one step in the method for manufacturing the light emitting element according to Embodiment 1. FIG. 5 is a schematic cross-sectional view showing one step in the method for manufacturing the light emitting element according to Embodiment 1. FIG. 5 is a schematic cross-sectional view showing one step in the method for manufacturing the light emitting element according to Embodiment 1. FIG. 5 is a schematic cross-sectional view showing one step in the method for manufacturing the light emitting element according to Embodiment 1. FIG. 5 is a schematic cross-sectional view showing one step in the method for manufacturing the light emitting element according to Embodiment 1. FIG. 5 is a schematic cross-sectional view showing one step in the method for manufacturing the light emitting element according to Embodiment 1. FIG. 5 is a schematic cross-sectional view showing one step in the method for manufacturing the light emitting element according to Embodiment 1. FIG. 5 is a schematic cross-sectional view showing one step in the method for manufacturing the light emitting element according to Embodiment 1. (A) is a schematic sectional drawing which shows the pn junction of a semiconductor fine particle, (b) is a schematic sectional drawing which shows the pn junction of the semiconductor fine particle of another example. (A)-(c) is a schematic sectional drawing which shows each process of the manufacturing method which forms the pn junction of the semiconductor fine particle of FIG.4 (b).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Lower electrode 3 Electron transport layer 3a First electron transport layer 3b Second electron transport layer 4 Light emitting layer 5 Hole transport layer 6 Upper electrode 7 Power source 10 Light emitting element 11, 11a Semiconductor fine particle 12 Dielectric 13a p-type part 13b n-type part 13c n-type part 23 p-type doped material

Claims (2)

An electron transport layer, a hole transport layer facing each other and spaced apart from each other, and a layer made of a plurality of semiconductor fine particles sandwiched between the electron transport layer and the hole transport layer A light emitting layer, a first electrode provided facing the electron transport layer and electrically connected thereto, and a second electrode provided facing the hole transport layer and electrically connected ; Is a light emitting device having a multilayer structure in which are sequentially stacked ,
The semiconductor fine particles constituting the light emitting layer have an n-type inner core and an outer shell in which a part of the n-type portion remains and a part of which becomes a p-type portion, and the p-type portion of the outer shell And a part of the n-type part of the outer shell, and a part of the p-type part of the outer shell is in contact with the hole transport layer. Is arranged so as to be in contact with the electron transport layer. An electron transport layer, a hole transport layer facing each other and spaced apart from each other, and a layer made of a plurality of semiconductor fine particles sandwiched between the electron transport layer and the hole transport layer A light emitting layer, a first electrode provided facing the electron transport layer and electrically connected thereto, and a second electrode provided facing the hole transport layer and electrically connected ; Is a method of manufacturing a light-emitting device having a multilayer structure in which are sequentially stacked ,
The semiconductor fine particles constituting the light emitting layer have an n-type inner core and an outer shell in which a part of the n-type portion remains and a part of which becomes a p-type portion, and the p-type portion of the outer shell And a pn junction formed at the interface between the n-type portion of the inner core,
A first electron transport layer is formed on a substrate, a second electron transport layer having fluidity is formed on the first electron transport layer, and then the semiconductor fine particles are formed on the second electron transport layer. Are arranged so that a part of the n-type part of the outer shell is in contact with the second electron transport layer, and a light-emitting layer is formed. Then, a part of the p-type part of the outer shell is formed on the semiconductor fine particles. A method for manufacturing a light-emitting element, comprising forming a hole transport layer so as to be in contact with a transport layer.

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