EP2652086A1

EP2652086A1 - Method for producing a radiation conversion element, radiation conversion element, and optoelectronic component containing a radiation conversion element

Info

Publication number: EP2652086A1
Application number: EP11794470.2A
Authority: EP
Inventors: Mikael Ahlstedt; Raquel De La Pena Alonso
Original assignee: Osram Opto Semiconductors GmbH
Current assignee: Ams Osram International GmbH
Priority date: 2010-12-13
Filing date: 2011-12-07
Publication date: 2013-10-23
Also published as: CN103261369A; WO2012080056A1; KR20130105685A; US20130320385A1; DE102010054279A1

Abstract

The invention relates to a method for producing a radiation conversion element, in which a solution is applied to a substrate, a gel is formed from the solution, and the gel is thermally treated. Moreover, a radiation conversion element is provided, which is produced according to the method. Moreover, an optoelectronic component is provided, which contains a radiation conversion element.

Description

description

Process for the preparation of a

Radiation conversion element, radiation conversion element and optoelectronic component containing a

Radiation conversion element

This patent application claims the priority of German patent application 10 2010 054 279.2, the disclosure of which is hereby incorporated by reference.

There will be a method of making a

Radiation conversion element specified as well as the

Radiation conversion element and an optoelectronic component with the radiation conversion element.

Radiation conversion elements can be used, for example, on semiconductor chips of radiation-emitting,

optoelectronic components such as LEDs are applied. The LEDs emit light at a certain wavelength, that of the

Radiation conversion element can be converted into light of different wavelengths.

An object of an embodiment of the invention is to provide an easily performed method for producing a radiation conversion element with which a radiation conversion element with improved properties can be produced. Other tasks are the

Provision of the radiation conversion element and an optoelectronic component, which the

Radiation conversion element contains. These objects are achieved by the method according to claim 1, which Radiation conversion element according to claim 8 and the optoelectronic component according to claim 15 solved.

Further embodiments of the method and of the

Radiation conversion element are the subject of dependent claims.

There will be a method of making a

Radiation conversion element indicated by the

Process steps A) Providing a substrate and a stable solution, the luminescent

B) application of the solution to the substrate, C) hydrolysis and condensation of the solution to form a gel, D) thermal treatment of the gel to form a conversion layer on the substrate. The conversion layer produced by this process can have a crystalline or glassy, ie amorphous structure. In the following, amorphous in connection with the finished conversion layer is understood to mean that crystalline dopant particles can be present in it.

By "precursor" in the context of Dotierstoffprekursoren compounds are meant, which undergo chemical reactions in the course of the process and thus be changed, but the actual dopant, as he after the

Process step D) present in the conversion layer is included from the beginning.

With this method, therefore, a solution with luminescent properties is applied to the substrate, which is formed into a gel layer. The gel layer used in the

Process step D) is further thermally treated and thus formed into a crystalline or amorphous conversion layer containing a dopant, due to In the layer existing luminescent dopants radiation from one wavelength to a larger or smaller depending on the type of dopant wavelength

convert.

Also, the substrate may have radiation-converting properties, so that the conversion layer can convert the already converted radiation even further and thus can cause a fine-tuning of the converted wavelength and thus the color impression for an external viewer of the emitted light. Thus, for example, a white light emitting device in whose

Beam path is applied to a radiation conversion element with the above properties, emit a cold white light for car lights or a warm white light for lighting in the living area.

With the method can easily a

Conversion layer are deposited on the substrate and thus a radiation conversion layer are obtained, which is dense, has a homogeneous doping and a small thickness. This procedure is due to the simple

Implementation also industrially applicable.

The hydrolysis and condensation in process step C) leads to a crosslinking of the solution and thus to the formation of a gel. The reactions that occur during the hydrolysis and

Condensation take place, are given in the formulas (I) to (III):

Rn-xM (OR) x + xH20 <-Rn-xM (OH) x + xROH (I) Rn-xM (OH) x + Rn-xM (OH) x <-> (R) n-xM (OH) xlOM (OH) x-1 (R) nx + (x-1) HÖH

(II) Rn-x M (OH) x + Rn-x M (OR) x <- (R) n-x M (OH) x I OM (OR) x-1 (R) n x + (x-1) ROH

(III) In all formulas, "R" represents an organic radical, such as straight or branched alkyl groups of any length, and the organic radicals in the inter-reacting molecules may be the same or different. "M" represents a metal, which may be "n" represents the valency of the metal on which the number of moieties attached to M is dependent. In the formula (I), the hydrolysis of a substituted

Metal alkoxide shown with water, in which one with x

Hydroxy groups and n-x organic radicals substituted metal and an alcohol arise. According to the formula (II), water can be condensed from two metal compounds each substituted with x-hydroxy groups and n-x organic groups. This can also be done according to formula (III) between a metal that is x

Substituted hydroxy groups and nx organic radicals, and a metal alkoxide take place. The reactions according to formulas (II) and (III) are reversible. The reaction scheme according to the formulas (I) to (III) can also be referred to as sol-gel chemistry. The hydrolysis and condensation in process step C) can be carried out at room temperature. According to one embodiment, the stable solution in the

Process step A) further comprises a solvent and

Metallprekusoren be added. Suitable solvents may be, for example, alcohols, such as isopropanol or ethanol, or acid / base catalysts, such as water with HCl or NH3. With the solvent, a suitable dilution of the solution can be achieved, and the

Drying rate and the homogenization of the solution can be influenced. Depending on the drying rate, the viscosity of the resulting gel can be influenced.

By "precursors" in the context of metal precursors is meant compounds which undergo chemical reactions during the process and are thus altered, but the metal which, after process step D) in the

Conversion layer exists, included from the beginning.

Metal precursors added to the solution may be selected from a group comprising metal alkoxides, acetates, chlorides and nitrates. The metals of this

For example, connections can be from a group

be selected, which comprises Al, Si, Ti and Zr. Generally, metal alkoxides have the formula M-O-R. M stands for the metal, R for an organic radical, which can be chosen arbitrarily.

Additionally, water may be added to the solution to promote hydrolysis. Furthermore, a complexing agent can be added to stabilize the solution. An exemplary complexing agent is acetylacetate. The

Ratio of the metal of the dopant precursor to all metals in the solution can be 0.5 to 20. The dopant precursors in process step A) can be selected from a group comprising metal alkoxides, acetates, chlorides and nitrates of the metals Eu, Ce, Ir, Er and Cs. The dopant precursors can also be called

Nanopowder dispersed in the solution. This will make the solution luminescent

Dotierstoffprekursoren added that form a gel in step C) together with the Metallprekursoren in the solution according to the reactions of the formulas (I) to (III), ie crosslink with each other. Both the metals of

Metal precursors as well as the metals of the

Dotierstoffprekursoren thereby become in the network

built-in .

The application in process step B) can be carried out by means of a method selected from the group consisting of spin coating, dip coating or spray coating

includes. With these methods, particularly thin layers can be applied, whereby after the gel formation and the thermal treatment, a thin conversion layer having radiation-converting properties can result. A small thickness of the conversion layer on the

Substrate results in that the conversion layer is formed substantially transparent.

The application methods used in process step B) are particularly inexpensive methods compared to conventional application methods, such as

for example CVD, PVD or sputtering.

By spin coating, both the thickness of the resulting conversion layer and the wavelength to which radiation is converted can be adjusted which in turn is due to the precisely adjustable thickness.

For example, if an LED with a

Radiation conversion element are provided, the conversion layer should be as transparent as possible.

Radiation converting materials, the radiation too

Converting wavelengths in the green or red region often have non-cubic crystal structures, making them difficult to translate into transparent materials

contribute. Therefore, it is important to make these materials as thin as possible as a radiation-converting, crystalline or amorphous conversion layer on the substrate so that their intrinsic absorption and scattering is reduced. This can be achieved by a method as described above.

Process step D) may comprise the steps D1) drying the gel, D2) calcining the gel to form an amorphous layer, D3) pyrolysis of the amorphous layer to form a conversion layer. The luminescent dopant is thus incorporated in the conversion layer.

Thus, the thermal treatment of process step D) is divided into three sub-steps. First, the gel is left for a few minutes at slightly elevated temperatures,

dried, for example, a temperature in the range 60 ° C to 180 ° C, then at higher temperatures,

for example, a temperature in the range 400 ° C to 600 ° C, calcined and finally a pyrolysis,

for example, at a temperature in the range 600 ° C to 1800 ° C subjected. The pyrolysis atmosphere can be a

Be oxygen, nitrogen or Formiergasatmosphäre. The calcination can be used to form an amorphous layer from the gel layer, which then becomes pyrolysis

Conversion layer, which is crystalline or amorphous, is formed. If the conversion layer is amorphous, crystalline dopant particles may be incorporated in it.

In one embodiment, the method steps B) to D) can be repeated at least twice. Thus, at least two, but also a plurality of superimposed radiation-converting, conversion layers on the

Substrate can be applied. A repetition of up to eight times is also conceivable. The repeated application of the solution to the substrate in process step B) can take place after process step D1), after process step D2) or after process step D3). In general, it makes sense to apply more layers if they are thinner. There can be so many layers

be applied one above the other, as long as no peeling effect of the layers occurs.

Thus, several, even different conversion layers can be generated on the substrate. The individual crystalline or amorphous layers may each have different thicknesses and / or different dopant concentrations and / or different dopants. So that can

For example, a larger dopant concentration in the entire conversion layers in each case very thin and therefore transparent individual layers are generated. It is also possible to apply a plurality of layers, which are made from the same solutions, in order to increase the effect of the radiation conversion by combining these prepared conversion layers. Thus, a method is provided in which a solution is applied to, for example, a radiation-converting substrate. The solution contains a mixture of liquid metal precursors and liquid

Dotierstoffprekursoren, in one embodiment, also dispersed nanopowder dopant precursors, which become a gel by hydrolysis and condensation and after a thermal treatment give a luminescent crystalline or amorphous conversion layer. The

The radiation-converting conversion layer can serve as a modifying radiation conversion layer to more precisely match the radiation converted by the radiation-converting substrate to the desired hue

to vote.

The conversion layer can, for example, convert small amounts of white-colored radiation to blue- or yellow-colored radiation, so that a cool-white radiation results. If warm white radiation is desired, the conversion layer may be formed to convert small amounts of white radiation into reds or greens

The method is a simple technology to apply a color-modifying conversion layer to a

Converter layer, the substrate to apply. The substrate may also be a radiation-inactive layer. Then the conversion layer on the substrate is the only radiation conversion layer that converts the radiation.

With this method can be particularly thin

Conversion layers, for example, 10 nm thick layers are produced, which is not conventional methods is possible. Due to the small thickness of the layers is a very accurate adjustment of the desired hue by

Radiation conversion possible.

Furthermore, the process offers so thin with that

Conversion layers are made, the opportunity, even non-transparent, for example, non-cubic

Apply materials as a very thin layer, whereby the light transmission through the layer is only slightly or not at all reduced

It will continue to be a radiation conversion element

provided by a method according to any of the above-mentioned embodiments and comprising a substrate and at least one conversion layer on the substrate. The radiation conversion element can in a

To be transparent in terms of leadership. This radiation, for example, from a semiconductor chip on which the

Radiation conversion element is applied, is emitted, freely pass through the radiation conversion element through, and at the same time the wavelength of the radiation are converted.

The substrate can convert radiation or become inactive

to be against radiation. A radiation converting

Substrate may include inorganic material. It may be, for example, to a radiation-converting materials containing ceramic, a luminescent glass or a

Glass ceramic act. If ceramics are used as the substrate, higher temperatures can be used in the thermal treatment in process step D), without the

Damage the substrate. For example, as a ceramic, a YAG ceramic can be used, which at temperatures of up to 1850 ° C is stable. If glasses are used as substrate, the temperature in process step D) must be below the

Glass transition temperature are. Has soda lime glass

For example, a glass transition point at 520 to 600 ° C and quartz glass at about 1175 ° C.

An inorganic radiation-converting substrate is favorable if further functional layers are to be deposited thereon. Inorganic radiation-converting

Substrates thus allow the application, for example, of additional inorganic functional layers which have to be prepared at higher temperatures in order to obtain their own

To produce functional properties. Thus, an inorganic radiation-converting substrate is therefore also suitable for applying a conversion layer by means of the abovementioned method, which comprises a thermal treatment.

The substrate may also have non-radiation-converting properties and only as a substrate for the

Applying and producing the conversion layer serve. In this case, the conversion layer is the only one

radiation-converting layer in the

Radiation conversion element.

The conversion layer may have a crystalline or amorphous structure. This is due to the above manufacturing process. In the crystalline or amorphous structure, a metal may be incorporated in a proportion of 0.05 mol% to 8 mol%, especially 1 mol% to 5 mol%. The metal may be selected from a group comprising Eu, Ce, Ir, Er and Cs. Depending on the concentration of these metals, which are dopants, in the conversion layer is more or less passing through the conversion layer Radiation converted. The color, that is to say the wavelength of the radiation emerging from the conversion layer, is thus determined by the concentration of the dopants in the

Conversion layer tunable.

The conversion layer may have a thickness which is selected from the range 10 nm to 5 μπι. The conversion layer may, for example, have 10 nm. In this case, a plurality of conversion layers may be stacked on the substrate to increase the effect of radiation conversion.

Good adhesion between the substrate and the conversion layer can be achieved by the manufacturing method. By taking place in step C) hydrolysis and condensation and bonds between a

inorganic substrate and the crosslinking gel layer arise. These bonds also stay in place during the

subsequent thermal treatment in step D), whereby a covalent bond between the

Conversion layer and the substrate is formed. The rougher the substrate is formed, the more bonds can be made to the gel, and the better the adhesion of the conversion layer to the substrate. Such bonds can be, for example, bonds between OH groups of the

Substrate and gel.

The surface of the conversion layer is further easy to modify, so that, if appropriate, a roughness can be produced which improves the radiation emission from the conversion layer. Finally, an optoelectronic component is provided which comprises a carrier, at least one

radiation-emitting semiconductor chip on the support and a radiation conversion element according to the above

Contains properties on the semiconductor chip. The

Radiation conversion element can convert the radiation emitted by the semiconductor chip radiation. This can be done either by conversion by means of a radiation-converting substrate and a converting modification by the

Conversion layer happen, or alone by the

Conversion layer when the substrate is inactive towards

Radiation is and the conversion layer sole

Radiation conversion layer is.

Such an optoelectronic component has an improved fine tuning of the emitted radiation, so that the desired wavelength of the emitted

Radiation can be adjusted exactly.

Such an optoelectronic component may be, for example, an LED.

With reference to the figure and the embodiment is intended to

Invention will be explained in more detail.

Figure 1 is a schematic side view of an optoelectronic device

Figure 2 Scheme of the method steps of the method for producing a radiation conversion element

Figure 1 shows the schematic side view of a

optoelectronic component comprising a carrier 10, a radiation-emitting semiconductor chip 20, a first and second contact 31 and 32, a housing 40, a potting 50, a bonding wire 33 and a radiation conversion element 60 comprises. The radiation conversion element 60 includes a substrate 61 and a conversion layer 62. The substrate 61 may itself be radiation-converting or inactive

to be against radiation. The conversion layer 62 is a radiation converting layer and may vary depending on

Embodiment of the substrate cause a modification of the wavelength of the radiation converted by the substrate or be sole radiation conversion layer. Of the

Semiconductor chip 20 may be radiation of one wavelength

which is converted to a desired wavelength by the radiation conversion element 60. The

Radiation conversion element 60 as well as the potting 50 are formed transparent.

The following is an example of producing a conversion layer 62 on a substrate 61.

First, a solution is prepared containing a mixture of metal precursors and luminescent dopant precursors. Metal precursors may include metal alkoxides, acetates, chlorides or nitrates. Also the

Dopant precursors may include metal alkoxides, acetates, chlorides and nitrates. The metals of

Metal precursors include one or more of Al, Si, Ti, and Zr, and the metals of the dopant precursors include one or more of Eu, Ce, Ir, Er, and Cs. The precursors can be stabilized prior to mixing to achieve ease of solution handling and avoid the formation of secondary phases. This solution is applied to a substrate, for example an inorganic substrate, which is formed from a ceramic, a glass or a glass ceramic, by means of spin coating, dip coating or spray coating. The solution on the substrate condenses and hydrolyzes to a gel at room temperature and is then dried at 110 ° C for a few minutes. In this case, a high degree of crosslinking forms in the gel layer. The drying step may be repeated several times to increase the preferred layer thickness

receive.

The thus coated substrate is then in

Oxygen atmosphere calcined at temperatures of up to 600 ° C to remove organic residues in the gel and to allow the formation of an inorganic, amorphous network.

The calcined network on the substrate is then subjected to pyrolysis at higher temperatures to allow crystallization of the amorphous layer. The atmosphere in the pyrolysis can be an oxygen,

Nitrogen or Formiergasatmosphere. The choice of the atmosphere is made depending on how the material of the amorphous layer is composed, what stoichiometric

Conditions are present and how are the oxidation states of the dopants.

The intensity of the radiation conversion by the

Conversion layer depends on both the thickness of the

Conversion layer as well as the concentration of the

Dopant in this layer from. The thickness of the

Conversion layer can by means of the application technique in

Process step B), the viscosity of the solution, ie the Amount of solvent in the solution provided in step A), and the number of conversion layers produced can be determined. The thicker the layer and the higher the concentration of dopants, the higher the intensity of the radiation conversion, that is, the more the entire radiation is shifted in the direction of higher or lower wavelengths.

The parameters of the deposition technique, such as the spin speed or time, can be varied to produce thicker and thinner conversion layers, respectively

manufacture. Thicker layers can be made by providing already cross-linked solutions of correspondingly high viscosity.

If the coating is repeated several times, the

Conversion layers are also made thicker. Repetitions are possible after drying the layer in process step D1), after calcination in

Process step D2) or after pyrolysis in

Process step D3). These possibilities, when another solution to form another conversion layer

can be applied, are also shown in Figure 2, where in addition also the process steps A) providing the solution and the process steps B) and C) applying the solution and hydrolysis and condensation before

Process step dl) are specified.

The invention described here is not by the

Description limited to the embodiments.

Rather, the invention includes any novel feature as well as any combination of features, which includes in particular any combination of features in the claims, even if this feature or this combination itself is not explicitly stated in the patent claims or exemplary embodiments.

Claims

claims

1. A method for producing a

Radiation conversion element (60) with the

Steps:

A) providing a substrate (61) and a stable solution comprising luminescent dopant precursors,

B) applying the solution to the substrate (61),

C) hydrolysis and condensation of the solution to form a gel,

D) Thermal treatment of the gel to form a

Conversion layer (62) on the substrate (61).

2. The method according to the preceding claim, wherein the stable solution in step A) continue to

Solvents and Metallprekursoren is added.

3. The method according to the preceding claim, wherein for the solution provided in step A) solution

Metal precursors are selected from a group comprising metal alkoxides, acetates, chlorides and nitrates.

4. The method according to any one of the preceding claims, wherein the Dotierstoffprekursoren in process step A) are selected from a group comprising metal alkoxides, acetates, - chlorides and nitrates of the metals Eu, Ce, Ir, Er and Cs.

5. The method according to any one of the preceding claims, wherein the application in step B) is carried out by a method which is selected from a group comprising spin coating, dip coating or spray coating.

6. The method according to any one of the preceding claims, wherein the method step D) the steps

D1) drying the gel,

D2) calcining the gel to form an amorphous layer, D3) pyrolysis of the amorphous layer to form a

Conversion layer (62).

7. The method according to any one of the preceding claims, wherein the method steps B) to D) at least twice

be repeated.

8. radiation conversion element (60) prepared by a method according to claims 1 to 7, comprising

a substrate (61) and at least one conversion layer (62) on the substrate (61).

9. radiation conversion element (60) according to the preceding claim, which is transparent.

10. Radiation conversion element (60) according to one of

Claims 8 or 9, wherein the substrate (61) radiation

converting or inactive to radiation.

11. Radiation conversion element (60) according to the preceding claim, wherein the radiation-converting substrate (61) comprises an inorganic material.

12 radiation conversion element (60) according to one of

Claims 8 to 11, wherein the conversion layer (62) has a crystalline or amorphous structure.

13. Radiation conversion element (60) according to the preceding claim, wherein in the crystalline or amorphous structure a metal selected from a group comprising Eu, Ce, Ir, Er and Cs in a proportion of 0.05 mol% to 8 mol%.

14. Radiation conversion element (60) according to one of

Claims 8 to 13, wherein the conversion layer (62) has a thickness which is selected from the range 10 nm to 5 μπι.

15. Optoelectronic component containing

a carrier (10),

- At least one radiation-emitting semiconductor chip (20) on the carrier (10) and

- A radiation conversion element (60) according to claims 8 to 14 on the semiconductor chip (20).