JP4856666B2 - Light emitting diode element and method for manufacturing the same - Google Patents

Description

  The present invention relates to a light-emitting diode element and a method for manufacturing the same, and more particularly to a light-emitting diode element having a broad emission spectrum in the visible light region and suitable for use as a white light source and a method for manufacturing the same.

  Since the invention of the GaN-based blue light-emitting diode element, the progress of the technology related to the light-emitting diode element has been remarkable. Among them, remarkable progress has been made year by year for the manufacturing technology of white light-emitting diode elements that can be used as a white light source having excellent efficiency and reliability.

  One of the conventionally proposed technologies for manufacturing white light-emitting diode elements is to mount red, yellow and green light-emitting diode elements in one package, and light up each light-emitting diode element simultaneously to emit light. A technique for realizing white light by mixing colors has been proposed (see, for example, Patent Document 1).

  As another white light emitting diode element manufacturing technique, a phosphor excited by light from a blue light emitting diode element or an ultraviolet light emitting diode element is provided in the vicinity of the light emitting diode element, and wavelength conversion is performed by this phosphor. Techniques have been proposed that generate white light (see, for example, Patent Document 2 and Patent Document 3).

Japanese Patent Laid-Open No. 07-211939 JP 2002-198573 A JP 2005-229048 A

  However, when white light is realized using the light emitting diode elements of three colors as disclosed in the above-mentioned Patent Document 1, the driving voltage and the light emission output intensity are different for each light emitting diode element of each color. In order to realize a white light source having an emission spectrum of 1, it is necessary to provide a complicated power supply circuit and a drive circuit. For this reason, when white light is realized using light emitting diode elements of three colors, there are problems that the number of manufacturing steps is increased and the manufacturing cost is likely to increase, and further, it is difficult to reduce the size of the light emitting diode.

  In addition, when white light is realized using a phosphor as disclosed in Patent Document 2 and Patent Document 3 described above, part of the light generated from the light emitting diode element is converted into thermal energy in the phosphor. In other words, there is a problem that light energy loss is large and energy utilization efficiency is poor.

  Therefore, the present invention has been devised in view of the above-described problems, and the object of the present invention is light emission that is easy to manufacture, has excellent energy utilization efficiency, and is suitable for use as a white light source. The object is to provide a method for manufacturing a diode element.

  In order to solve the above-described problems, the present inventor has first group III containing a gallium compound or an aluminum compound in a chamber in which a substrate on which a plurality of columnar nanostructures are formed is installed. A source gas, a group V source gas, and a second source gas containing an indium compound are supplied into the chamber and irradiated with light having a wavelength longer than the absorption edge wavelength of the second group III source gas. Accordingly, the second source gas is decomposed based on near-field light generated according to the shape of the columnar nanostructure, and the In group III-V compound semiconductor layer is formed on the outer surface of the columnar nanostructure. Invented a method of manufacturing a light-emitting diode device, characterized by having a step of growing the substrate.

That is, in the method for manufacturing a light-emitting diode device according to claim 1 of the present application, the first containing a gallium compound or an aluminum compound in a chamber in which a substrate on which a plurality of columnar nanostructures are formed is installed. A group III source gas, a group V source gas, and a second source gas containing an indium compound are supplied into the chamber, and the first group III source gas, the group V source gas, and the second group III source material are supplied. Gas is decomposed and deposited on the outer surface of the columnar nanostructure and the substrate, and by irradiating light having a wavelength longer than the absorption edge wavelength of the second group III source gas, based on the near-field light is generated in accordance with the shape by decomposing the second group III source gas, the composition ratio of indium gallium or aluminum, the corners of the columnar nano-structure and root portion Oite large, characterized by having a step of growing the group III-V compound semiconductor layer having a smaller becomes such concentration distribution as away from the corner portion and the root portion on the outer surface of the columnar nanostructure.

According to a second aspect of the present invention, there is provided a method for manufacturing a light-emitting diode device according to the first aspect of the present invention, wherein the step of growing the III-V compound semiconductor layer is formed according to the shape of the columnar nanostructure. Near-field light is generated in a local region, and the second source gas is decomposed based on the generated near-field light.

According to a third aspect of the present invention, there is provided a method for manufacturing a light-emitting diode device according to the first or second aspect of the present invention, wherein the step of growing the III-V compound semiconductor layer is performed on the outer surface of the columnar nanostructure. The method further comprises the step of growing a first conductivity type cladding layer, and after the step of growing the III-V compound semiconductor layer, the second conductivity type cladding layer is grown on the outer surface of the columnar nanostructure. The method further includes a step.

According to a fourth aspect of the present invention, there is provided a method for manufacturing a light emitting diode device according to the first or second aspect of the present invention, wherein in the step of growing the III-V group compound semiconductor layer, the columnar nanostructure is interposed between the substrate and the substrate. After the step of growing the group III-V compound semiconductor layer on the outer surface of the columnar nanostructure of the substrate on which the first conductivity type cladding layer is laminated, and growing the group III-V compound semiconductor layer The method further comprises the step of growing a clad layer of the second conductivity type on the outer surface of the columnar nanostructure.

The method for manufacturing a light-emitting diode element according to claim 5 of the present application is the invention according to any one of claims 1 to 4 , wherein the columnar nanostructure is formed in the step of growing the III-V compound semiconductor layer. The III-V compound semiconductor layer is grown on the outer peripheral surface of the columnar nanostructure of a substrate on which nanorods made of ZnO are formed.

A method for manufacturing a light-emitting diode element according to claim 6 of the present application is the invention according to any one of claims 1 to 5 , wherein in the step of growing the III-V group compound semiconductor layer, the first source gas and The group V source gas is heated to a predetermined temperature or decomposed by plasma discharge to grow the group III-V compound semiconductor layer.

A manufacturing method of a light emitting diode element according to claim 7 of the present application is the invention according to any one of claims 1 to 6 , wherein in the step of growing the III-V compound semiconductor layer, the first group III Instead of supplying the source gas, gallium atoms or aluminum atoms are supplied into the chamber by molecular beam epitaxy to grow the III-V group compound semiconductor layer.

The inventor also includes a substrate, a plurality of columnar nanostructures formed on the surface of the substrate, laminated on the outer surface of the columnar nanostructure, and contains gallium or aluminum and indium. A group III-V compound semiconductor layer, in which the composition ratio of gallium or aluminum to indium is large at the corners and roots of the columnar nanostructure , and the corners and roots The light-emitting diode element according to claim 8 is invented, wherein the light-emitting diode element has a concentration distribution that decreases with increasing distance from the portion .

The light-emitting diode element according to claim 9 of the present invention is the light-emitting diode element according to claim 8 , wherein the first conductive type cladding layer, the III-V group compound semiconductor layer, and the first layer are formed on the outer surface of the columnar nanostructure. A two-conductivity-type clad layer is sequentially laminated.

A light-emitting diode device according to claim 10 of the present invention is the light-emitting diode device according to claim 9, wherein the columnar nanostructure is formed on a first conductivity type clad layer stacked on the substrate, and the columnar nanostructure is formed. The III-V group compound semiconductor layer and the second conductivity type cladding layer are sequentially stacked on the outer surface of the structure.

A light emitting diode device according to claim 11 of the present invention is the light emitting diode device according to claim 9 or 10 , wherein the first conductivity type cladding layer, the III-V compound semiconductor layer, and the second conductivity type cladding layer are formed on the first conductivity type cladding layer. A pair of electrodes for applying a voltage is further provided.

The light-emitting diode element according to claim 12 of the present invention is characterized in that, in the invention according to any one of claims 9 to 11 , the columnar nanostructure is a nanorod made of ZnO.

With the method of manufacturing a light emitting diode device to which the present invention is applied, a group III source gas such as TMIn or a group V source gas such as NH ₃ is heated on the surface of the layer on which the active layer 15 is to be stacked, as shown in FIG. It is decomposed by dissociation or the like and grows. In addition, near-field light is generated based on the light emitted from the light source 43 in the corner portion 13a and the boundary portion 13b of the nanorod 13, that is, in a local region in which near-field light having a strong electric field strength is likely to be generated. Due to the generated near-field light, TMIn is decomposed in large quantities by photodissociation and grows in the local region. Here, since the difference between the irradiated light and the absorption edge wavelength is smaller in TMIn, which is a source gas of In, than TMG, TMAl, etc., which are source gases other than In, the amount of decomposition of the source gas other than In In contrast, the amount of In source gas is decomposed by about 1000 times. For this reason, the In composition ratio increases in the vicinity of the local region, and the In composition ratio continuously decreases as the distance from the local region increases. That is, an active layer having an In concentration distribution corresponding to the shape of the nanorod 13 can be obtained by the method for manufacturing a light-emitting diode element to which the present invention is applied.

  In addition, the light emitting diode element obtained by the method of manufacturing a light emitting diode element to which the present invention is applied includes an In layer III-V compound semiconductor layer containing In and other group III elements, and other than In. The concentration distribution with respect to the group III element differs depending on the shape of the nanorod 13. In the region where the concentration distribution of other In group III elements is large, the band gap becomes smaller and the emission wavelength becomes longer, and in the region where the concentration distribution of other In group III elements is small, the band gap becomes larger. The emission wavelength is shortened. For this reason, in the vicinity of a local region formed according to the shape of the nanorod 13, such as the corner portion 13a and the boundary portion 13b of the nanorod 13, which is a portion having a large concentration distribution with respect to other group III elements of In, For example, radiant light such as red is obtained, and radiant light having different colors continuously from yellow, green, and blue, for example, is obtained from the red region as the distance from the local region increases. This is because, for each nanorod 13, for example, a broad emission spectrum from an emission color obtained when the band gap such as red is relatively small to an emission color obtained when the band gap such as blue is relatively large. This means that it is possible to obtain emitted light, that is, it is possible to obtain an active layer 15 that can be used as a white light source. For this reason, the light emitting diode element 1 in which a plurality of such nanorods 13 are formed can be used as a white light source.

  Hereinafter, as a best mode for carrying out the present invention, a method for manufacturing a light-emitting diode element that can be used as a white light source will be described in detail with reference to the drawings.

  First, a light emitting diode element formed by a method for manufacturing a light emitting diode element to which the present invention is applied will be described.

  FIG. 1 shows a configuration of a light-emitting diode element 1 formed by a method for manufacturing a light-emitting diode element to which the present invention is applied, wherein (a) is a schematic sectional side view, and (b) is a plan view thereof. (C) has shown the partially expanded sectional side view.

  As shown in FIG. 1, the light-emitting diode element 1 includes a substrate 11 and a plurality of nanorods 13 formed on the surface of the substrate 11. As shown in FIGS. 1A and 1C, an n-type cladding layer 12 is laminated on the substrate 11, and a plurality of nanorods 13 are formed on the n-type cladding layer 12. ing. An active layer 15, a transparent insulating layer 16, and a p-type cladding layer 17 are sequentially stacked on the outer surfaces of the plurality of nanorods 13 and the n-type cladding layer 12. Further, a part of the upper surface 12a of the n-type cladding layer 12 is formed so as to be exposed, and an electrode pad 18 is attached to the exposed upper surface 12a. An electrode pad 19 is attached to the surface of the p-type cladding layer 17.

The substrate 11 is used for depositing and growing a semiconductor layer on the surface thereof. The material of the substrate 11 is made of, for example, sapphire (Al ₂ O ₃ ) or silicon carbide (SiC), but is not limited thereto.

  As shown in FIG. 2, the nanorod 13 is a columnar nanostructure formed so as to be substantially upright with respect to the surface of the substrate 11. The material of the nanorod 13 is made of ZnO in the present embodiment, but is not limited thereto, and may be made of, for example, GaN, AlN, AlGaN, or AlGaInN.

  The manufacturing method of the nanorod 13 is not particularly limited, and may be embodied by any known technique. The nanorods 13 are manufactured by, for example, metal organic chemical vapor deposition (Metal Organic Chemical Vapor Deposition).

  The n-type cladding layer 12 is GaN doped with an n-type impurity element such as Si in the present embodiment. The p-type cladding layer 17 is GaN doped with a p-type impurity element such as Mg in the present embodiment. Other examples of the n-type cladding layer 12 and the p-type cladding layer 17 include AlN. However, the present invention is not limited to this, and the clad layer may have any known composition.

The transparent insulating layer 16 is laminated to insulate the plurality of nanorods 13 formed on the substrate 11 and to protect the nanorods 13 themselves from an impact applied to the plurality of nanorods 13 . In addition, the transparent insulating layer 16 serves as a base layer that allows the upper part of the active layer 15 formed on the surface of the nanorod 13 to be electrically connected in common by the p-type cladding layer 17. Therefore, the transparent insulating layer 16 is configured such that the height of the upper end portion 16a is lower than the height of the upper end portion 15a of the active layer 15, as shown in FIG. The material of the transparent insulating layer 16 is not particularly limited. For example, the transparent insulating layer 16 is embodied by transparent SOG (Spin On Glass), SiO _2, epoxy resin, or the like.

  The electrode pad 18 and the electrode pad 19 are attached as a set of electrode terminals for applying a voltage to the n-type cladding layer 12 and the p-type cladding layer 17. The material of the electrode pad 18 and the electrode pad 19 is not particularly limited. For example, the electrode pad 18 and the electrode pad 19 have a thickness of about 3 to 7 nm, and any one or two selected from Ti, Al, Pd, Au, and the like. It is comprised by the above. A wire (not shown) is bonded to the electrode pad 18 and the electrode pad 19, and a voltage is thereby applied.

The active layer 15 is the most important semiconductor layer in the present invention. The active layer 15 is a semiconductor layer that emits light when the p-type cladding layer 17 is energized to the n-type cladding layer 12 , that is, when energized in the forward direction. In this embodiment, the active layer 15 includes gallium (Ga), indium (In), and nitrogen (N), and is configured as an In-based III-V group compound semiconductor represented by InGaN. is there. Ga and In contained in the active layer 15 satisfy the condition that the main emission peak of In belongs to a wavelength region longer than the main emission peak of Ga.

The active layer 15 is not limited to the above-described InGaN, but contains In as a group III element and one or two of aluminum (Al) or Ga, and as a group V element. Any one of N, phosphorus (P), and arsenic (As ) may be contained. The active layer 15 is configured, for example, as a ternary mixed crystal semiconductor layer such as InAlN or a quaternary mixed crystal semiconductor layer such as AlInGaN or AlInGaP in addition to InGaN, but contains In. There is no particular limitation as long as it is configured as a known ternary mixed crystal, quaternary mixed crystal, or ternary mixed crystal semiconductor layer.

  Hereinafter, in the present embodiment, the active layer 15 will be described using the active layer 15 configured as an In-based III-V compound semiconductor of Ga and In and N as an example.

As shown in FIG. 3, the active layer 15 is formed so as to have an In concentration distribution corresponding to the shape of the nanorod 13 by a method for manufacturing a light-emitting diode element to which the present invention is applied. This In concentration distribution is represented by a composition ratio of In _x Ga _(1-x) N (0 ≦ x ≦ 1) at a position corresponding to the shape of the nanorod 13. The concentration distribution of the active layer 15 is, for example, in the vicinity of the upper corner 13a of the nanorod 13 or in the vicinity of the boundary 13b between the n-type cladding layer 12 and the nanorod 13 where the active layer 15 is to be laminated. The composition ratio of In to Ga is high, and the composition ratio of In to Ga decreases as the distance from the corner portion 13a or the boundary portion 13b increases. This is based on the fact that near-field light is generated in a local region such as the corner portion 13a and the boundary portion 13b, which is formed according to the shape of the nanorod 13, as will be described later.

  Next, a crystal growth apparatus 3 for realizing a method for manufacturing a light emitting diode element to which the present invention is applied as schematically shown in FIG. 4 will be described.

  This crystal growth apparatus 3 is an apparatus used for realizing the MOVPE method.

  The crystal growth apparatus 3 is disposed in the chamber 31, a stage 33 for placing the substrate 11, a plurality of gas supply pipes 35 for supplying a source gas into the chamber 31, and the chamber 31. A gas exhaust pipe 37 for exhausting the raw material gas and the like inside, and an opening window 39 for introducing light into the chamber 31 are provided.

  In the chamber 31, source gases serving as raw materials for the respective semiconductor layers such as the n-type cladding layer 12 and the active layer 15 are supplied from a plurality of gas supply pipes 35. A pressure sensor (not shown) for detecting the pressure in the chamber 31 is provided in the chamber 31. Based on the pressure detected by the pressure sensor, the gas supply amount from the gas supply pipe 35 and the gas exhaust pipe 37 are used. The internal pressure in the chamber 31 can be automatically controlled by adjusting the exhaust amount.

  The crystal growth apparatus 3 further includes a plurality of RF (Radio Frequency) heaters 41 provided outside the chamber 31 and around the stage 33, and a temperature sensor (not shown) provided inside the chamber 31. . The crystal growth apparatus 3 can control the temperature inside the chamber 31, particularly around the stage 33, to a predetermined temperature by the RF heater 41 based on the temperature detected by the temperature sensor.

  The crystal growth apparatus 3 is provided with a light source 43 for irradiating light onto the stage 33 outside the chamber 31. The light source 43 emits light having a predetermined wavelength based on control by a driving power source (not shown). The light emitted from the light source 43 irradiates the substrate 11 placed on the stage 33 through the opening window 39 of the chamber 31.

The light source 43 is embodied by, for example, a He—Ne laser oscillator, an Ar laser oscillator, a He—Cd laser oscillator, a CO ₂ laser oscillator, or a semiconductor laser oscillator. Note that an irradiation optical system may be provided in order to control the beam diameter and beam shape of the light emitted from the light source 43 and narrow the range of light irradiation.

  Next, a method for manufacturing the light-emitting diode element 1 using the crystal growth apparatus 3 having such a configuration will be described.

First, as shown in FIG. 5A, the substrate 11 on which nothing is formed is placed on the stage 33 in the chamber 31, and the n-type cladding layer 12 is grown on the substrate 11. In this embodiment, since the n-type cladding layer 12 is GaN, a gallium compound TMG (trimethylgallium) is used as a group III source gas of a gallium source from a gas supply pipe 35, and a nitrogen compound is used as a group V source gas of a nitrogen source. NH ₃ is introduced, and SiH ₄ for doping Si into the layer is introduced. Note that since GaN has n-type characteristics due to nitrogen vacancies, oxygen impurities, or the like without introducing Si, the introduction of SiH ₄ may be omitted. In this case, for example, the temperature is 400 to 500 ° C., the pressure is 1 torr to 760 torr (atmospheric pressure), and the flow rates of TMG, NH ₃ and SiH ₄ are about 30 to 70 sccm, 1000 to 2000 sccm, and 5 to 20 sccm, respectively. Adjust to.

  Next, as shown in FIG. 5B, a plurality of nanorods 13 made of ZnO are formed on the n-type cladding layer 12. In this case, diethylzinc gas of zinc compound as the source gas of the zinc source and oxygen as the source gas of the oxygen source are supplied from the gas supply pipe 35, and the temperature and pressure are adjusted to a predetermined range to form the nanorods 13. become. In this case, for example, the temperature is adjusted to 450 ° C. ± 10%, and the pressure is adjusted to about 1 to 760 torr (atmospheric pressure). The diethyl zinc gas may be an organic metal gas made of a compound containing zinc, and the oxygen may be a gas or vapor made of a compound containing an oxygen element such as nitrogen dioxide.

Next, as shown in FIG. 5C, the active layer 15 is grown on the outer surface of the nanorod 13 and on the n-type cladding layer 12. In this case, TMG of a gallium compound as a group III source gas of a gallium source, TMIn (trimethylindium) of an indium compound as a group III source gas of an indium source, and NH ₃ as a group V source gas of a nitrogen source are supplied from a gas supply pipe 35. Will do. Furthermore, in order to grow the active layer 15, light having a wavelength longer than the absorption edge wavelength of TMIn which is a group III source gas of the indium source is irradiated onto the substrate 11 . In this case, the temperature on the substrate 11 is adjusted to be 500 ° C. or higher, which is the temperature at which TMG and TMIn can be thermally dissociated, and the wavelength of light emitted from the light source 43 is the absorption of TMIn. Since the edge wavelength is about 300 nm, adjustment is made to be about 320 to 450 nm. As the light source 43, a He—Cd laser oscillator, a CO ₂ laser oscillator, or a semiconductor laser oscillator whose wavelengths of oscillated light are about 325 nm, 350 nm, and 410 nm, respectively, can be used. Further, for example, the pressure is adjusted to 1 to 760 (atmospheric pressure) torr, TMG, TMIn, and NH ₃ to 30 to 70 sccm, 10 to 40 sccm, and 1000 to 2000 sccm, respectively.

By adjusting in this way, as shown in FIG. 6, the outer surface of the nanorod 13 is a surface of the layer on which the active layer 15 is to be laminated, such as a group III source gas of TMG or TMIn or a group V source gas of NH _3. On the upper surface and the surface of the n-type cladding layer 12, decomposition is performed by thermal dissociation, and Ga, In, and N are deposited. Further, near-field light is generated based on the light emitted from the light source 43 in the corner portion 13a and the boundary portion 13b of the nanorod 13, that is, in a local region in which near-field light having high emission intensity is likely to be generated. This means that near-field light having different electric field strengths is generated at a site corresponding to the shape of the nanorod 13. Based on the near-field light generated according to the shape of the nanorod 13, TMIn is decomposed in large quantities into In by photodissociation, and as a result, a large amount of In is present in local regions such as the corner portions 13a and the boundary portions 13b of the nanorods 13. Will be deposited. In this way, the active layer 15 is grown on the outer surface of the nanorod 13 and the surface of the n-type cladding layer 12 by decomposing and depositing Ga, N, and In.

  Here, since the absorption edge wavelength of TMG is about 250 nm and the absorption edge wavelength of TMIn is about 300 nm, when irradiating light with a wavelength of about 320 to 450 nm, as described later, depending on the propagation light, each raw material Although the gas is not photodissociated, each source gas is photodissociated depending on near-field light. In particular, it is known that the absorption coefficient of the source gas with respect to the irradiated light rapidly decreases as the wavelength of the irradiated light shifts from the absorption edge wavelength of the source gas to the longer wavelength range. For this reason, TMIn in which the difference between the irradiated light and the absorption edge wavelength is smaller than that of TMG is decomposed by about 1000 times as much as the decomposition amount of TMG. Then, the In generated by being decomposed in a large amount as described above is deposited and diffused in the vicinity of the corner portion 13a and the boundary portion 13b of the nanorod 13 and thereby grows. Thereby, the concentration distribution of In according to the shape of the nanorod 13 Therefore, the active layers 15 having different values are formed.

  The reason why the concentration distribution of In continuously decreases as the distance from the corner 13a and the boundary 13b of the nanorod 13 decreases is as follows. That is, the raw material gas decomposed based on the near-field light is decomposed through a non-adiabatic process as will be described later. Here, the amount of the raw material gas decomposed by the non-adiabatic process is proportional to the product of the light intensity and the light intensity gradient, and the raw material gas decomposed by the non-adiabatic process is expressed by the following equation (A). It is proportional to f (r) expressed. In the following formula (A), I (r) refers to the light intensity at the position r, and the position r is, for example, a coordinate in an orthogonal coordinate system composed of the x-axis, y-axis, and z-axis that are orthogonal to each other. It refers to the position represented by (x, y, z).

  The generation distribution of the near-field light has a property that it becomes maximum in a local region such as the corner portion 13a of the nanorod 13 and rapidly decreases as the distance from the local region increases. Here, for example, in the place where the near-field light is generated as in the range indicated as the near-field light shown in FIG. At a location slightly deviated from the location where the oozing starts, the value of the light intensity gradient becomes zero, and the source gas is not photodissociated. Further, in the place where the near-field light is generated, the value of the light intensity gradient does not change so much, but the light intensity itself rapidly decreases as the distance from the local region increases. For this reason, the value of f (r) continuously decreases as the distance from the local region increases, and in proportion to this, the decomposition amount of In also decreases continuously as the distance from the corner portion 13a of the nanorod 13 and the like. Will do.

Next, as shown in FIG. 7A, a transparent insulating layer 16 is formed between the nanorods 13 . The transparent insulating layer 16 is formed by applying the above-described SOG, SiO ₂ , epoxy resin or the like through a spin coating method or the like.

Next, as shown in FIG. 7B, a p-type cladding layer 17 is grown on the active layer 15 and the transparent insulating layer 16. In the present embodiment, since the p-type cladding layer 17 is GaN, a source gas containing TMG and NH ₃ and Cp ₂ Mg for doping Mg into the layer are introduced from the gas supply pipe 35. In this case, for example, the temperature is adjusted to 400 to 600 ° C., the pressure to 1 to 760 torr, the flow rates of TMG, NH ₃ and Cp ₂ Mg are adjusted to 30 to 70 sccm, 1000 to 2000 sccm, and 5 to 20 sccm, respectively.

Next, as shown in FIG. 7C, an electrode pad 18 and an electrode pad 19 for applying a voltage are formed. In order to form the electrode pad 18, the p-type cladding layer 17, the transparent insulating layer 16, the active layer 15, and the nanorod 13 as shown in FIG. The partial range S1 is selectively removed by etching or the like. Next, the electrode pad 18 and the electrode pad 19 are formed using an electron beam evaporation method or the like.

The light emitting diode element 1 is manufactured through the steps as described above. With the method of manufacturing a light emitting diode device to which the present invention is applied, a group III source gas such as TMIn or a group V source gas such as NH ₃ is heated on the surface of the layer on which the active layer 15 is to be stacked, as shown in FIG. It is decomposed by dissociation and grows. In addition, near-field light is generated based on the light emitted from the light source 43 in the corner portion 13a and the boundary portion 13b of the nanorod 13, that is, in a local region in which near-field light having a strong electric field strength is easily generated. Due to the generated near-field light, TMIn is decomposed in large quantities by photodissociation and grows in the local region. Here, since the difference between the irradiated light and the absorption edge wavelength is smaller in TMIn, which is a source gas of In, than TMG, TMAl, etc., which are source gases other than In, the amount of decomposition of the source gas other than In In contrast, the amount of In source gas is decomposed by about 1000 times. For this reason, the In composition ratio increases in the vicinity of the local region, and the In composition ratio continuously decreases as the distance from the local region increases. That is, an active layer having an In concentration distribution corresponding to the shape of the nanorod 13 can be obtained by the method for manufacturing a light-emitting diode element to which the present invention is applied.

  Further, the light-emitting diode element 1 obtained by the present invention has a concentration distribution of the active layer 15 which is an In-based III-V compound semiconductor layer containing In and other Group III elements with respect to other Group III elements of In. However, it differs depending on the shape of the nanorods 13. In the region where the concentration distribution of other In group III elements is large, the band gap becomes smaller and the emission wavelength becomes longer, and in the region where the concentration distribution of other In group III elements is small, the band gap becomes larger. The emission wavelength is shortened. For this reason, in the vicinity of a local region formed according to the shape of the nanorod 13, such as the corner portion 13a and the boundary portion 13b of the nanorod 13, which is a portion having a large concentration distribution with respect to other group III elements of In, For example, radiant light such as red is obtained, and radiant light having different colors continuously from yellow, green, and blue is obtained from the red region as the distance from the local region increases. This is because, for each nanorod 13, for example, emission light having a wide emission spectrum from the emission color when the band gap is relatively small, such as red, to the emission color when the band gap is relatively large, such as blue, is obtained. This means that the active layer 15 usable as a white light source can be obtained. For this reason, the light emitting diode element 1 in which a plurality of such nanorods 13 are formed can be used as a white light source.

  In particular, since the light-emitting diode element 1 obtained by the manufacturing method according to the present invention does not use a phosphor, light energy loss caused by using the phosphor does not occur, and the energy utilization efficiency is extremely excellent. .

  Also, unlike the white light emitting diode elements obtained by using the conventional three color light emitting diode elements, it is not necessary to adjust the driving voltage, the light emission output, etc. for each color light emitting diode element, compared with the conventional technique. Thus, white light can be easily realized.

In addition, in the method of manufacturing a light emitting diode device to which the present invention is applied, an active layer having a different concentration distribution of In to Ga according to the shape of the nanorod 13 is introduced into the chamber 31 with a predetermined source gas, upon being irradiated with light, since the thus obtained only performed on the basis of the MOCVD method which has been conventionally used, production becomes very easy.

  When the substrate 11 is irradiated with light having a wavelength longer than the absorption edge wavelength of various source gases such as TMIn, each source gas is not photodissociated by propagating light, and each source gas only by near-field light. The reason for the photodissociation of is as follows.

  FIG. 8 shows the relationship of potential energy with respect to the internuclear distance of gas molecules constituting a source gas such as TMIn. Usually, light having a photon energy greater than the energy difference Ea between the ground level and the excited level relative to the gas molecule, that is, light having a wavelength shorter than the absorption edge wavelength of the gas molecule (hereinafter referred to as resonance of this light). When irradiated with light, the gas molecules are directly excited to the excited level. Since this excitation level exceeds the dissociation energy Eb, active species and decomposition products are generated by photolysis of gas molecules in the direction indicated by the arrows.

  In the present invention, absorption of gas molecules is not used, instead of using a resonance process in which gas molecules are irradiated with resonance light as described above, and the gas molecules are directly excited to the excitation level and then photolyzed. Light is emitted from gas molecules using a non-resonant process in which gas molecules are photolyzed by near-field light generated by irradiating light having a wavelength longer than the edge wavelength (hereinafter referred to as non-resonant light). Decompose.

  In normal photodissociation using propagating light, since the electric field intensity of propagating light is a uniform distribution within the space of the molecular size, only light electrons among the nuclei and electrons that make up gas molecules react to light. However, the internuclear distance cannot be changed. On the other hand, in the photodissociation using near-field light, the electric field intensity of the near-field light is violently displaced in the molecular size space, resulting in an uneven distribution. For this reason, in the photodissociation using near-field light, not only the electrons of gas molecules but also the nuclei react to change the distance between the nuclei, causing direct excitation to the vibrational level of the molecules. (Non-adiabatic chemical reaction).

Thus, when the source gas is irradiated with non-resonant light that is near-field light, the gas molecules are excited to the molecular vibration level. The molecule will not be excited. For this reason, in the present invention, as shown in FIG. 6, photodissociation occurs only in the local region formed according to the shape and position of the nanorods 13 in which near-field light is generated, and the other substrates. 11 and the surface of the nanorod 13 do not generate photodissociation, but only thermal dissociation by heating the inside of the chamber 31 occurs.

  Here, when non-resonant light, which is near-field light, is irradiated, the path from the gas level to the molecular vibration level, that is, the non-resonant process, as shown in FIG. The processes are classified into process T1, process T2, and process T3. The process T1 refers to a process in which gas molecules are excited through a plurality of molecular vibration levels and, as a result, are excited to an excited level and then dissociated into active species or the like. Further, in the process T2, when light having a light energy equal to or higher than the dissociation energy Eb of the gas molecule is irradiated, the gas molecule is excited to a molecular vibration level having an energy level equal to or higher than the dissociation energy Eb. A process that is directly dissociated into species. In process T3, when light having light energy equal to or lower than Eb of the gas molecule is irradiated, the gas molecule is excited to the molecular vibration level of the energy level of dissociation energy Eb through a plurality of molecular vibration levels. As a result, it refers to the process of being directly dissociated into active species.

  Near-field light refers to non-propagating light that clings to and localizes the surface of an object when the surface of the object is irradiated with propagating light. It is known that this near-field light is generated by generating a very strong electric field component in the local region as described above. In addition, the local area | region here means the corner | angular part 13a of the nanorod 13 etc. which are formed according to the shape of the nanorod 13, for example. This local region is a concept that includes the tip of the nanorod 13 as long as the shape of the tip of the nanorod 13 is sharpened toward the tip, and irregularities are provided in part of the shape of the nanorod 13. The concept includes the corners formed by the irregularities. Further, the local region is a concept including the boundary portion 13b between the nanorod 13 and another layer such as the n-type cladding layer 12.

  As mentioned above, although the form for implementing this invention was illustrated, the concrete structure and material can apply what was variously deformed.

  For example, in the above-described embodiment, the example in which the p-type cladding layer 17 is stacked on the n-type cladding layer 12 has been described. However, the semiconductor layers stacked on both sides of the active layer 15 have different conductivity types. The p-type cladding layer 17 may be laminated on the substrate 11 and the n-type cladding layer 12 may be laminated thereon. Further, the positions and shapes of the electrode pad 18 and the electrode pad 19 are not limited to the above-described example, and a voltage is applied to the n-type cladding layer 12 and the p-type cladding layer 17 and the active layer 15 interposed therebetween. If possible, other positions and shapes may be used.

  Further, depending on the material such as the substrate 11 and the n-type cladding layer 12, the difference in lattice constant between adjacent layers increases, and the amount of lattice defects and the like of other layers stacked on the layer increases. In order to prevent this, a buffer layer may be laminated between the respective layers. This buffer layer is formed to alleviate this difference in lattice constant, and is embodied by, for example, AlN, GaN, AlGaN, InGaN, InAlGaN, or the like. Incidentally, it goes without saying that the buffer layer may be formed even when the lattice constants of the substrate 11, the nanorods 13 and the active layer 15 are not significantly different.

In the above-described embodiment, the case where Ga growth and In growth are simultaneously performed has been described as an example. However, these steps may be performed separately. In this case, as shown in FIG. 10A, after the nanorods 13 are formed on the n-type cladding layer 12, NH ₃ and TMG are supplied from the gas supply pipe 35 as shown in FIG. 10B. Then, the first active layer 15 is grown around the nanorods 13 and on the substrate 11. In this stage, the first group III-V compound semiconductor layer is an active layer 15 does not include In, composition ratio in the first active layer 15 is constant. The conditions such as temperature and pressure in this step are adjusted such that the temperature is 400 to 500 ° C., the pressure is 1 torr to 760 torr, the flow rates of TMG and NH ₃ are about 30 to 70 sccm and 1000 to 2000 sccm, respectively. .

Next, NH ₃ and TMIn are supplied from the gas supply pipe 35, and further, TMIn, which is a source gas containing In, is irradiated onto the substrate 11 with light having a wavelength longer than the absorption edge wavelength. Near-field light is generated in a local region formed in accordance with the shape and position of the first, and a III-V group compound semiconductor layer as the second active layer 21 is grown on the first active layer 15 . Conditions such as temperature and pressure in this step are not limited as long as NH ₃ can be thermally dissociated. For example, the temperature is 500 ° C. or higher, the pressure is 1 torr to 760 torr, the flow rates of TMIn and NH ₃ are 30 to 70 sccm, 1000 to 1000, respectively. Adjust to 2000 sccm.

  Then, TMIn is decomposed into In by photodissociation by the generated near-field light, and In is grown in the local region. Thereafter, as described above, a process of providing the transparent insulating layer 16, the p-type cladding layer 17, the electrode pad 18, and the electrode pad 19 is performed.

As shown in FIG. 11, the light-emitting diode device 1 thus obtained has a second active activity corresponding to the shape of the nanorod 13 on the GaN layer, which is the first active layer 15 stacked on the surface of the nanorod 13. The InN layer which is the layer 21 is laminated. In this case, radiant light having a continuous emission spectrum cannot be obtained because the composition ratio of In and other group III elements is continuously different, but GaN having different emission colors per nanorod. A layer or an InN layer is formed at a location corresponding to the shape of the nanorod 13. For this reason, the light emitting diode element 1 in which a plurality of such nanorods 13 are formed has an emission spectrum corresponding to each layer at the time of light emission, and the colors emitted from each layer are mixed, It can be used as a white light source.

In the above embodiment, the active layer 15 is configured as a compound semiconductor of Ga and In and N. However, as described above, this is a ternary mixed crystal such as InAlN or AlInGaN. Alternatively, it may be composed of a quaternary mixed crystal semiconductor layer such as AlInGaP. For example, if the active layer 15 is composed of InAlN, the emission peak of Al N is about 200 nm, since the emission peak of the Ga N is about 400 nm, the active layer 15 composed of InAlN, the nanorods 13 When the concentration distribution of In in the layer varies depending on the shape, a broad emission spectrum from purple to red is obtained at the time of light emission. Further, the active layer 15 made of AlInGaN has an emission spectrum of 360 to 370 nm at the time of light emission because the concentration distribution of In in the layer varies depending on the shape of the nanorod 13. As described above, the In-based III-V compound semiconductor active layer 15 obtained by applying the present invention has a different In concentration distribution in the layer depending on the shape of the nanorods 13, so that at the time of light emission, It has an emission spectrum with a wide band according to the concentration distribution.

Examples of the group III source gas used when Al is included in the active layer 15 include TMAl (trimethylaluminum) and TEAl (triethylaluminum). The group III source gas used when Ga is included in the active layer 15 includes TEG (triethylgallium) in addition to TMG. The group III source gas used when In is included in the active layer 15 includes TEIn (triethylindium) in addition to TMIn. An example of the group V source gas used when P is included in the active layer 15 is PH ₃ (phosphine). The group V source gas used when As is included in the active layer 15 is, for example, AsH ₃ (arsine).

  Further, in the above-described embodiment, an example in which the nanorods 13 are directly formed on the n-type cladding layer 12 has been shown, but the nanorods 13 may be directly formed on the substrate 11. Further, when the substrate 11 is disposed in the chamber 31, the substrate 11 on which the n-type cladding layer 12 and the nanorod 13 are formed in advance may be disposed in the chamber 31.

  The nanorods 13 are most preferably composed of ZnO. This is because the lattice constants of the active layer 15 made of InGaN and the nanorods 13 made of ZnO are close to each other, and the active layer 15 with few lattice defects can be deposited on the nanorods 13.

  Moreover, it is preferable that the length from the upper end to the surface of the layer which should laminate | stack the active layer 15 shall be 500 nm or less. This is because it is difficult to reduce the density of the nanorods 13 made of ZnO. Therefore, if the length of the nanorods 13 exceeds 500 nm, a sufficient amount of source gas reaches the lower part of the ZnO nanorods 13 having a density of a certain amount or more. This is because it is difficult to grow the active layer 15 below the nanorods 13.

  When the active layer 15 is grown, when various group III source gases and group V source gases are decomposed, the substrate 11 is heated to a predetermined temperature at which each source gas can be thermally dissociated, and decomposed by plasma discharge. You may make it do. Further, as described later, the active layer 15 may be grown by molecular beam epitaxy. In this case, instead of supplying a source gas containing a gallium compound and an aluminum compound into the chamber, the active layer 15 is grown by supplying gallium atoms or aluminum atoms into the chamber by molecular beam epitaxy. Become.

  Further, as an alternative to the nanorods 13 formed by a predetermined method, a plurality of columnar nanostructures are formed on a substrate by electron beam lithography, X-ray lithography, ion beam lithography, and the like, and the above-described light emission is performed using this. The diode element 1 may be manufactured.

  In addition, the temperature control mechanism for detecting the temperature in the chamber 31 and controlling the temperature in the chamber 31 to a predetermined region is not limited to the combination of the RF heater and the temperature sensor described above, but any known one. It may consist of a configuration. Further, the pressure adjusting mechanism for detecting the pressure in the chamber 31 and controlling the pressure in the chamber 31 to a predetermined region is not limited to the gas exhaust pipe 37 and the pressure sensor described above, and any known configuration is possible. It may consist of.

  In the present invention, crystal growth of a semiconductor layer such as an active layer or a clad layer was performed using MOCVD. However, the present invention is not limited to this, and molecular beam epitaxy (Molecular Beam Epitaxy) is used. The semiconductor layer may be grown using any known physical vapor deposition method or chemical vapor deposition method such as.

It is a figure which shows the structure of the light emitting diode element to which this invention is applied, (a) is the schematic sectional side view, (b) is the top view, (c) is the partially expanded sectional side view. It is a schematic perspective view which shows an example of a structure of a nanorod. It is a figure for demonstrating the composition ratio of In of an active layer. It is the schematic of the crystal growth apparatus for implement | achieving the manufacturing method of the light emitting diode element to which this invention is applied. It is a figure for demonstrating the procedure of the manufacturing method of a light emitting diode element. It is a figure for demonstrating the point which laminates | stacks an active layer on the circumference | surroundings of a nanorod and a board | substrate. It is a figure for demonstrating the procedure of the manufacturing method of a light emitting diode element. It is a figure for demonstrating resonant light and non-resonant light. It is a figure for demonstrating a non-resonance process. It is a figure for demonstrating the procedure of the manufacturing method of a light emitting diode element. It is a figure which shows the other structure of the light emitting diode element to which this invention is applied, (a) is the schematic sectional side view, (b) is the partially expanded sectional side view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emitting diode element 3 Crystal growth apparatus 11 Substrate 12 N-type clad layer 13 Nanorod 13a Corner part 13b Boundary part 15 Active layer 16 Transparent insulating layer 17 P-type clad layer 18, 19 Electrode pad 31 Chamber 33 Stage 35 Gas supply pipe 37 Gas Exhaust pipe 39 Open window 41 RF heater 43 Light source

Claims (12)

A first group III source gas containing a gallium compound or an aluminum compound, a group V source gas, and an indium compound are contained in a chamber in which a substrate on which a plurality of columnar nanostructures are formed is installed. The second group III source gas is supplied into the chamber, and the first group III source gas, the group V source gas, and the second group III source gas are decomposed, and the columnar nanostructure and the outer surface of the substrate And irradiating light having a wavelength longer than the absorption edge wavelength of the second group III source gas, based on the near-field light generated according to the shape of the columnar nanostructure. the second group III source gas is decomposed, the composition ratio of indium gallium or aluminum is greater at the corners and the root portion of the pillar-shaped nanostructure, as separated from the corner portion and the root portion Method of manufacturing a light emitting diode device characterized by comprising a step of growing the group III-V compound semiconductor layer having a concentration distribution such that smaller on the outer surface of the columnar nanostructures. In the step of growing the III-V compound semiconductor layer, near-field light is generated in a local region formed according to the shape of the columnar nanostructure, and the second field is generated based on the generated near-field light. The method for producing a light-emitting diode element according to claim 1, wherein the group III source gas is decomposed. Before the step of growing the III-V compound semiconductor layer, further comprising the step of growing a cladding layer of the first conductivity type on the outer surface of the columnar nanostructure,
After the step of growing the group III-V compound semiconductor layer, according to claim 1 or 2, characterized by further comprising a step of growing a second conductivity type cladding layer on the outer surface of the columnar nanostructure Manufacturing method of the light emitting diode element. In the step of growing the group III-V compound semiconductor layer, on the outer surface of the columnar nanostructure of the substrate in which a cladding layer of a first conductivity type is stacked between the columnar nanostructure and the substrate, Grow III-V compound semiconductor layer,
After the step of growing the group III-V compound semiconductor layer, according to claim 1 or 2, characterized by further comprising a step of growing a second conductivity type cladding layer on the outer surface of the columnar nanostructure Manufacturing method of the light emitting diode element. In the step of growing the group III-V compound semiconductor layer, the group III-V compound semiconductor layer is formed on the outer peripheral surface of the columnar nanostructure of the substrate on which nanorods made of ZnO are formed as the columnar nanostructure. method of manufacturing a light emitting diode device according to any one of claim 1 to 4, characterized in that growing. In the step of growing the group III-V compound semiconductor layer, the first group III source gas and the group V source gas are decomposed by heating the substrate to a predetermined temperature or by plasma discharge, and the III-V method of manufacturing a light emitting diode device according to any one of claim 1 to 5, characterized in that growing family compound semiconductor layer. In the step of growing the III-V compound semiconductor layer, instead of supplying the first group III source gas, gallium atoms or aluminum atoms are supplied into the chamber by molecular beam epitaxy, and the III- method of manufacturing a light emitting diode device according to any one of claim 1 to 6, characterized in that V group compound semiconductor layer. A substrate,
A plurality of columnar nanostructures formed on the surface of the substrate;
A III-V group compound semiconductor layer laminated on the outer surface of the columnar nanostructure and containing gallium or aluminum and indium;
The III-V group compound semiconductor layer has a concentration distribution in which the composition ratio of gallium or aluminum to indium is large at the corners and roots of the columnar nanostructure and decreases as the distance from the corners and roots increases. A light emitting diode element characterized by comprising: On the outer surface of the columnar nano-structure, the cladding layer of the first conductivity type, according to claim 8, wherein the said group III-V compound semiconductor layer and the cladding layer of the second conductivity type are sequentially laminated Light emitting diode element. The columnar nanostructure is formed on a first conductivity type cladding layer laminated on the substrate,
9. The light emitting diode element according to claim 8 , wherein the III-V compound semiconductor layer and the second conductivity type cladding layer are sequentially laminated on the outer surface of the columnar nanostructure. 10. The method according to claim 9 , further comprising a pair of electrodes for applying a voltage to the first conductivity type cladding layer, the III-V group compound semiconductor layer, and the second conductivity type cladding layer. Or a light-emitting diode device according to 10 ; The light emitting diode element according to any one of claims 8 to 11 , wherein the columnar nanostructure is a nanorod made of ZnO.

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