TWI423468B - Light emitting device and method for manufacturing the same - Google Patents

Description

Light-emitting device manufacturing method and light-emitting device

The present invention relates to a method of manufacturing a light-emitting device including a partial conductive portion and a light-emitting device.

In the conventional method for producing a light-emitting diode (LED) formed of a nitride-based compound semiconductor, the following method is widely known: an n-type GaN layer, a light-emitting layer, and p are formed on a sapphire substrate. The GaN layer is sequentially grown to form a compound semiconductor layer. Then, etching is performed from the p-type GaN layer to a part of the n-type GaN layer to expose the n-type GaN layer, and a p-type electrode is formed on the p-type GaN layer; on the other hand, on the exposed n-type GaN layer The p-type electrode individually forms an n-type electrode.

Further, in the light-emitting element described in Patent Document 1, the buffer layer, the n-layer, and the semi-insulating layer (I layer) are sequentially formed on the sapphire substrate, and then n is formed on the surface of the I layer. The side electrode is subjected to heat treatment to form a low-resistance region directly under the n-side electrode, and thereafter to form an I-side electrode.

According to the light-emitting element described in Patent Document 1, since the low-resistance region can be formed in the I-layer region directly under the n-side electrode, current can flow between the I-side electrode and the n-side electrode without manufacturing a contact hole.

[Patent Document 1] Japanese Patent Laid-Open No. Hei 4-273175

However, in the method of manufacturing an LED manufactured by a conventional nitride-based compound semiconductor, when an n-type electrode is formed, a step of removing a compound semiconductor by photolithography and etching is required. Further, the p-type electrode and the p-type GaN layer; the n-type electrode is in contact with the n-type GaN layer, and the p-type electrode and the n-type electrode are made of the same material from the viewpoint that the electrode and the semiconductor must be in ohmic contact. There are difficulties in forming the system. Therefore, it is necessary to form the p-type electrode and the n-type electrode separately in separate steps. Therefore, in the conventional method for producing a nitride-based compound semiconductor LED, it is difficult to simplify the process of the LED.

Moreover, in the manufacture of the light-emitting element described in Patent Document 1, it is necessary to perform a heat treatment step after providing the n-side electrode, and it is necessary to form an I-side electrode after the heat treatment step. In other words, in the light-emitting element described in Patent Document 1, the n-side electrode and the I-side electrode cannot be simultaneously formed. Therefore, in the method for producing a light-emitting device described in Patent Document 1, it is difficult to simplify the process of the light-emitting device.

Accordingly, the present invention has been made in view of the above circumstances, and an object thereof is to simplify the process of a light-emitting device.

In order to achieve the above object, the present invention provides a method of manufacturing a light-emitting device, comprising: a first semiconductor layer of a first conductivity type and a second semiconductor layer of a second conductivity type different from the first conductivity type; A voltage is applied to the first semiconductor layer and the second semiconductor layer to emit light. The method includes an electrode forming step of forming a first electrode and a second electrode spaced apart from the first electrode on the first semiconductor layer, and a voltage application step of applying a voltage to the first electrode formed in each of the electrode forming steps Between the second electrode and the second electrode, the second electrode and the second semiconductor layer are electrically double-conductive.

Further, in the method of manufacturing a light-emitting device, the first conductivity type is a p-type, the second conductivity type is an n-type, and the voltage application step applies a voltage between the first electrode and the second electrode to break the first semiconductor. A part of the layer and the second semiconductor layer are pn-bonded so that the second electrode and the second semiconductor layer are electrically double-conductive.

Further, in the method of manufacturing the light-emitting device described above, in the electrode forming step, the first electrode and the second electrode may be formed in a state where the area of the second electrode is smaller than the area of the first electrode. Further, the electrode forming step can simultaneously form the first electrode and the second electrode. Further, in the method of manufacturing the light-emitting device described above, the electrode forming step may form the first electrode and the second electrode from the same material.

In order to achieve the above object, the present invention provides a light-emitting device comprising: a first semiconductor layer of a first conductivity type; a first semiconductor layer provided thereon, and a second conductivity type different from the first conductivity type a semiconductor layer; a first electrode provided on the first semiconductor layer; a second electrode provided separately from the first electrode on the first semiconductor layer; formed under the second electrode, and the second electrode and the second semiconductor Partial conduction of the layered electrical double-conducting.

Further, in the above-described light-emitting device, a part of the conduction portion can be formed by applying a predetermined voltage between the first electrode and the second electrode. Further, in the above-described light-emitting device, the area of the second electrode may be smaller than the area of the first electrode. Further, in the above-described light-emitting device, the material for forming the first electrode and the material for forming the second electrode may be the same.

According to the invention, the process of the illuminating device can be simplistic.

Best form for implementing the invention [First Embodiment]

Fig. 1 is a schematic perspective view showing a light-emitting device according to a first embodiment of the present invention. Fig. 2 is a schematic longitudinal cross-sectional view showing a light-emitting device according to a first embodiment of the present invention.

(Structure of Light Emitting Device 1)

As shown in FIG. 1, the light-emitting device 1 according to the first embodiment includes a semiconductor stacked structure including a sapphire substrate 10 having a (0001) plane, an n-type GaN layer 20, and a second conductive layer provided on the sapphire substrate 10. The second semiconductor layer of the type; the light-emitting layer 22 is provided on the n-type GaN layer 20; and the p-type GaN layer 24 is provided on the light-emitting layer 22, and the first semiconductor layer of the first conductivity type different from the second conductivity type.

Further, the light-emitting device 1 includes a P-type electrode 40, a first electrode provided in a predetermined region on the p-type GaN layer 24, and an n-type electrode 42 separated from the P-type electrode 40 on the p-type GaN layer 24. The second electrode is provided to be opened. Further, as shown in FIG. 2, the light-emitting device 1 penetrates both the p-type GaN layer 24 and the light-emitting layer 22 under the n-type electrode 42 and reaches a predetermined region up to a partial region of the n-type GaN layer 20, and includes n. The type electrode 42 and the n-type GaN layer 20 are electrically connectable to each other.

Here, the n-type GaN layer 20, the light-emitting layer 22, and the p-type GaN layer 24 are each composed of, for example, a group III nitride compound semiconductor formed by a metal organic chemical vapor deposition (MOCVD). Floor.

For example, the n-type GaN layer 20 is formed of n-GaN doped with a predetermined amount of Si as an n-type dopant. Further, the light-emitting layer 22 has a quantum well structure formed of In _x Ga ₁ - _x N/GaN. Further, the p-type GaN layer 24 is formed of p-GaN doped with a predetermined amount of Mg as a p-type dopant.

Further, the n-type electrode 42 provided on the p-type GaN layer 24 according to the present embodiment is provided at a position spaced apart from the p-type electrode 40, that is, electrically cut from each other. For example, the n-type electrode 42 is provided in a predetermined region in the vicinity of a corner including the top surface of the p-type GaN layer 24 of the light-emitting device 1 having a slightly square shape in plan view. Further, the p-type electrode 40 is spaced apart from the n-type electrode 42, that is, the n-type electrode 42 is provided separately from the n-type electrode 42 at a predetermined area including at least one corner of the top surface of the p-type GaN layer 24.

Here, the p-type electrode 40 and the n-type electrode 42 are each formed of the same material. For example, each of the p-type electrode 40 and the n-type electrode 42 is formed of indium tin oxide (ITO). Further, in the n-type electrode 42 of the present embodiment, the area of the n-type electrode 42 is smaller than the area of the p-type electrode 40.

The partial conductive portion 26 is formed below the n-type electrode 42 and is a region in which the n-type electrode 42 and the n-type GaN layer 20 are electrically bidirectional. Due to the presence of a portion of the via portion 26, an electrical bidirectional conduction is formed between the p-type GaN layer 24 and the n-type GaN layer 20. Specifically, the partial conductive portion 26 is a region in which at least a part of the p-type GaN layer 24 and the light-emitting layer 22 under the n-type electrode 42 are electrically connected to a part of the n-type GaN layer 20 . That is, in the partial conduction portion 26, no rectifying property is generated between the p-type GaN layer 24 and the n-type GaN layer 20.

For example, the partial conduction portion 26 applies a voltage for destroying the pn junction when the p-type GaN layer 24 and the n-type GaN layer 20 are pn-bonded to each other between the p-type electrode 40 and the n-type electrode 42; The n-type electrode 42 and the n-type GaN layer 20 are electrically formed by directly under the electrode 42 and by constituting a partial pn junction between the p-type GaN layer 24 and the n-type GaN layer 20 under the n-type electrode 42. Sexually-directed area.

Further, before the formation of the n-type GaN layer 20, a buffer layer made of AlN or GaN may be formed on the sapphire substrate 10 by MOCVD. Further, the quantum well structure of the light-emitting layer 22 may form either a single quantum well structure or a multiple quantum well structure; or a light-emitting layer having no quantum well structure may be employed. Further, on the p-type GaN layer 24, a doping concentration higher than the Mg doping amount of the p-type GaN layer 24 can be used, and a Mg-doped p-type contact layer (p+-type GaN layer) can be formed by MOCVD. .

Further, the buffer layer, the n-type GaN layer 20, the light-emitting layer 22, the p-type GaN layer 24, and the p-type contact layer provided on the sapphire substrate 10 may be a molecular beam epitaxy (MBE, Molecular Beam Epitaxy) or a hydride. A compound semiconductor layer formed by a vapor phase epitaxy method (HVPE, Halide Vapor Phase Epitaxy) or the like.

Further, the p-type electrode 40 and the n-type electrode 42 may be formed of zinc oxide (ZnO). Alternatively, the p-type electrode 40 and the n-type electrode 42 may be formed of a metal material mainly composed of Ag, Al, Ni, Au, Pd, Cr, or the like. Further, a pad electrode can be formed in a partial region on the p-type electrode 40. Similarly, the pad electrode may be formed in a predetermined region on the n-type electrode 42. At this time, a material for forming both the pad electrode provided on the p-type electrode 40 and the pad electrode provided on the n-type electrode 42 may be formed of the same material. For example, the pad electrode may be mainly formed of a metal material such as Ti, Ni, or Au.

The light-emitting device 1 of the present embodiment constituted by the above configuration is an LED that emits light of a wavelength of a blue region. For example, the light-emitting device 1 is a blue LED that faces upward, and emits light having a peak wavelength of 470 nm when the forward voltage is 3.5 (V) and the forward current is 20 mA. As for the planar size of the light-emitting device 1, the vertical dimension and the lateral dimension are each slightly 350 μm.

Further, the light-emitting device 1 may be an LED that emits light having a peak wavelength in an ultraviolet region, a near-ultraviolet region, or a green region; however, the region of the peak wavelength of light emitted from the LED is not limited to the wavelength of the regions. Further, in other modifications, the planar size of the light-emitting device 1 is not limited to this. For example, it can also be designed such that the vertical dimension and the lateral dimension are each slightly 1 mm.

(Method of Manufacturing Light Emitting Device 1)

Fig. 3(a) is a longitudinal sectional view showing an epitaxial growth substrate. 3(b) is a longitudinal cross-sectional view showing an electrode formed on an epitaxial growth substrate. 3(c) is a longitudinal cross-sectional view showing the formation of the p-type electrode and the n-type electrode. Further, Fig. 3(d) is a longitudinal cross-sectional view showing a part of the conduction portion.

First, the group III nitride compound semiconductor is epitaxially grown by MOCVD on the surface of the sapphire substrate 10 to form the epitaxial growth substrate 2. In other words, on the sapphire substrate 10, the n-type GaN layer 20, the light-emitting layer 22, and the p-type GaN layer 24 are sequentially epitaxially grown to form an epitaxial growth substrate 2 (Fig. 3(a)).

Next, the electrode 46 is formed by vacuum deposition on the p-type GaN layer 24, and the p-type GaN layer 24 is covered with the electrode 46 (Fig. 3(b)). In the present embodiment, indium tin oxide of a transparent electrode is used as the electrode 46. Further, the electrode 46 may be formed of a metal material such as Ag, Al, Ni, Au, Pd or Cr by a sputtering method.

Then, using a photolithography technique, a mask formed by the photoresist is formed on a predetermined area on the electrode 46. Here, a mask is formed so that the area of the n-type electrode 42 is smaller than the area of the p-type electrode 40. Next, using the etching technique, the electrode 46 other than the region covered by the mask is removed to form the p-type electrode 40 and the n-type electrode 42. Therefore, both the p-type electrode 40 and the n-type electrode 42 are simultaneously formed of the same material. Thereby, the substrate 3 on which the electrodes of the p-type electrode 40 and the n-type electrode 42 are provided is provided on the epitaxial growth substrate 2 (FIG. 3(c)).

Further, before the electrode 46 shown in FIG. 3(b) is formed, a predetermined mask pattern is provided by using a photolithography technique; after the electrode 46 is formed on the formed mask pattern, the p-type electrode 40 can be formed by peeling off. And the n-type electrode 42.

Next, for the purpose of applying a predetermined voltage between the p-type electrode 40 and the n-type electrode 42, the probe 50 for voltage application is brought into contact with the p-type electrode 40, and the probe 52 for voltage application is brought into contact with The n-type electrode 42. Then, a predetermined voltage is applied between the p-type electrode 40 and the n-type electrode 42 via the probe 50 and the probe 52. Further, the probe 50 and the probe 52 are formed of, for example, a metal such as tungsten or an electrically conductive material.

That is, first, the p-type electrode 40 is set to the positive side, and the n-type electrode 42 is set to the negative side. Then, an excessive voltage is applied between the p-type electrode 40 and the n-type electrode 42 to form an electrically conductive bi-directional state between the n-type electrode 42 and the n-type GaN layer 20. That is, at least a portion of the p-type GaN layer 24 under the n-type electrode 42 and the n-type GaN layer 20 are electrically bidirectionally applied between the p-type electrode 40 and the n-type electrode 42 by applying an excessive voltage. Turn on.

Specifically, the semiconductor bonding of both the p-type GaN layer 24 and the light-emitting layer 22 under the n-type electrode 42 and the semiconductor junction formed by the light-emitting layer 22 and the n-type GaN layer 20 destroy the two One of the bonding portions is applied between the p-type electrode 40 and the n-type electrode 42 by interposing the p-type GaN layer 24 with the reverse voltage of the light-emitting layer 22 sufficiently electrically conductive with the n-type GaN layer 20.

Thereby, a region from the p-type GaN layer 24 to a part of the n-type GaN layer 20 under the n-type electrode 42 , that is, a region from the p-type GaN layer 24 that penetrates the light-emitting layer 22 and reaches a part of the n-type GaN layer 20 is formed. A portion of the conductive portion 26 that electrically connects the p-type GaN layer 24 and the n-type GaN layer 20 (Fig. 3(d)). Thereby, the light-emitting device 1 is formed.

The magnitude of the reverse voltage is such a degree that the semiconductor junction formed between the p-type GaN layer 24 and the n-type GaN layer 20 is broken and the p-type GaN layer 24 and the n-type GaN layer 20 are electrically double-conducted. For example, when the p-type GaN layer 24 and the n-type GaN layer 20 are both pn-bonded, a portion of the conductive portion 26 is formed by applying a voltage that breaks the pn junction to between the p-type electrode 40 and the n-type electrode 42. .

When the light-emitting layer 22 is formed between the p-type GaN layer 24 and the n-type GaN layer 20, the bonding between the p-type GaN layer 24 and the light-emitting layer 22 is broken, and the light-emitting layer 22 and the n-type GaN layer 20 are formed. The voltage of the size of the junction is applied between the p-type electrode 40 and the n-type electrode 42 to form a partial conduction portion 26.

Further, when the light-emitting layer 22 has a quantum well structure, bonding between the p-type GaN layer 24 and the quantum well structure, bonding of a plurality of well layers and a plurality of barrier layers included in the quantum well structure, and quantum well structure are performed. A voltage of a size to be bonded to the n-type GaN layer 20 is applied between the p-type electrode 40 and the n-type electrode 42 to form a partial conductive portion 26.

(Operation of Light Emitting Device 1)

First, when a predetermined electric power is supplied to the p-type electrode 40 and the n-type electrode 42, current flows from the n-type electrode 42 through the partial conduction portion 26, and from the partial conduction portion 26 to the light-emitting layer via the n-type GaN layer 20. twenty two. Then, the light-emitting layer 22 emits light of a predetermined wavelength range due to the current to be supplied. The light emitted from the light-emitting layer 22 propagates through the sapphire substrate 10 and is radiated to the outside of the light-emitting device 1.

Further, a portion of the conduction portion 26 provided under the n-type electrode 42 is turned on to supply the current supplied from the n-type electrode 42 to the n-type GaN layer 20. Therefore, in the region where the partial conductive portion 26 is formed, since the light-emitting layer 22 in which the region has existed before the partial conductive portion 26 is formed is destroyed and the function as the light-emitting layer 22 is lost, the light-emitting layer 22 is disposed under the n-type electrode 42. Does not shine.

(Effects of the first embodiment)

According to the light-emitting device 1 of the present embodiment, both the p-type electrode 40 and the n-type electrode 42 are simultaneously formed on the p-type GaN layer 24, and a predetermined voltage is applied to the p-type electrode 40 and the n-type. Between the electrodes 42, the pn junction included in the region from the p-type GaN layer 24 to the portion of the n-type GaN layer 20 under the n-type electrode 42 can be broken. Thereby, the region from the p-type GaN layer 24 to a part of the n-type GaN layer 20 under the n-type electrode 42 can be electrically double-conducted. Therefore, the step of etching from the p-type GaN layer 24 to a part of the n-type GaN layer 20 necessary for the manufacturing method of the conventional light-emitting device, and the step of separately forming the p-type electrode and the n-type electrode can be omitted. In the step, the process of the light-emitting device 1 can be greatly simplified. Thereby, the reduction in the manufacturing cost of the light-emitting device 1 and the increase in the throughput can be achieved.

Further, in the present embodiment, the p-type GaN layer 24 under the p-type electrode 40 and the n-type GaN layer 20 are joined in the forward direction; on the other hand, the p-type GaN layer under the n-type electrode 42 exists. The bonding of both the 24 and n-type GaN layers 20 is reversed. Therefore, the bonding under the n-type electrode 42 is broken due to the engagement of the excessively large electrode under the n-type electrode 42. Here, when the area of the n-type electrode 42 is smaller than the area of the p-type electrode 40, and the area of the n-type electrode 42 is the same as the area of the p-type electrode 40, the n-type electrode 42 is broken. The amount of current required for the engagement is reduced. Therefore, in the present embodiment, by reducing the area of the n-type electrode 42 to the area of the p-type electrode 40, it is possible to prevent the current amount from increasing rapidly and the bonding under the p-type electrode 40 to be broken.

[Second Embodiment]

Fig. 4 is a plan view showing a substrate on which a part of the electrode is attached to half of the process of the light-emitting device according to the second embodiment of the present invention.

The substrate 3 to which the electrode is attached according to the present embodiment includes the peripheral electrode 44 and a plurality of p-type electrodes 40 and a plurality of n-type electrodes 42 as shown in FIG. 3(c). Since the substrate 3 is approximately the same, detailed description is omitted except for the difference from the substrate 3 to which the electrode is attached as illustrated in FIG. 3(c).

(Structure of substrate 3 with electrodes attached)

The substrate 3 to which the electrode is attached according to the present embodiment includes the outer peripheral electrode 44 on the p-type GaN surface 25, and the unit electrode 48 including the p-type electrode 40 and the n-type electrode 42 as a group inside the outer peripheral electrode 44. . The plurality of unit electrodes 48 are formed, for example, along the shape of the outer peripheral electrode inner edge 402 of the inner edge of the outer peripheral electrode 44 at a predetermined interval. For example, a plurality of unit electrodes 48 are formed in a matrix on the p-type GaN surface 25.

(Method of Manufacturing Substrate 3 with Electrodes)

The outer peripheral electrode 44 is formed of the same material as the p-type electrode 40 and the n-type electrode 42 included in the unit electrode 48. In other words, the plurality of unit electrodes 48 and the outer peripheral electrodes 44 are simultaneously formed on the entire surface of the epitaxial growth substrate 2 by using an optical lithography technique, a vacuum vapor deposition technique, or a sputtering method (electrode forming treatment).

For example, a mask such as a photoresist is formed on the epitaxial growth substrate 2, that is, a p-type GaN surface 25 formed on the p-type GaN layer 24, except for a region where the plurality of unit electrodes 48 and the outer peripheral electrode 44 are to be formed. . Then, on the entire surface of the p-type GaN surface 25 after the mask was formed, 300 nm thick Ni was formed by sputtering. Then, a plurality of unit electrodes 48 and outer peripheral electrodes 44 are formed by a peeling method. Subsequently, a heat treatment was applied for 5 minutes (alloying treatment) at 400 2 deg.] C, in N ₂ atmosphere is formed a plurality of unit electrodes 48 and 44 of the outer periphery of the epitaxial growth substrate electrode. The substrate 3 to which the electrode is attached can be obtained by the treatment of the alloy.

Further, in another example, ITO may be formed on the entire surface of the p-type GaN surface 25 of the epitaxial growth substrate 2. Then, a mask is formed with a photoresist or the like in a region where the plurality of unit electrodes 48 and the peripheral electrodes 44 are to be formed. Next, the ITO is removed by etching in addition to the portion covered by the mask. Thereby, a plurality of unit electrodes 48 and outer peripheral electrodes 44 are provided on the epitaxial growth substrate 2, and the substrate 3 to which the electrodes are attached may be formed.

Next, the outer peripheral electrode 44 is set on the positive side, and the n-type electrode 42 provided in one unit electrode 48 is set on the negative side, and a predetermined voltage is applied between the outer peripheral electrode 44 and the n-type electrode 42. For example, in the present embodiment, a voltage of about 100 (V) is applied between the outer peripheral electrode 44 and the n-type electrode 42 to break the p-type GaN layer 24 and the light-emitting layer 22 under the n-type electrode 42. The semiconductor bonding and the semiconductor layer formed by the light-emitting layer 22 and the n-type GaN layer 20 (voltage application processing). This voltage application process is applied to a plurality of n-type electrodes 42. Therefore, a plurality of partial conductive portions 26 are formed below each of the plurality of n-type electrodes 42.

Then, after the voltage application process is performed, the p-type electrode 40 is set on the positive side for each of the plurality of unit electrodes 48, and the n-type electrode 42 is set on the negative side, and the p-type electrode 40 and the n-type are used. The electrodes 42 are energized, and the electrical characteristics and optical characteristics of the substrate 3 with the electrodes below the unit electrodes 48 are measured separately (characteristic evaluation processing).

Further, after voltage application processing and characteristic evaluation processing are performed on one of the plurality of unit electrodes 48, the other unit electrodes 48 can be sequentially subjected to voltage application processing and characteristic evaluation processing. Alternatively, the voltage application processing may be performed for all of the plurality of unit electrodes 48, and after the partial conduction portion 26 is formed for each of the plurality of unit electrodes 48, the characteristic evaluation processing may be performed for all of the plurality of unit electrodes 48.

Next, the sapphire substrate 10 is polished to a predetermined thickness, for example, about 100 μm (polishing treatment). Then, in the region of the substrate 3 on which the electrodes are attached, in which the unit electrodes 48 are not provided, the plurality of unit electrodes 48 are cut down in plan view and individually included in the substantially rectangular regions. That is, it is cut into a predetermined wafer shape (for example, a slightly square shape) and a wafer size (for example, an angle of 350 μm). Next, by cutting, a plurality of light-emitting devices 1 are formed along the etched shape (wafer processing).

Further, in the present embodiment, the outer peripheral electrode 44 is substantially quadrangular in plan view, but the shape of the outer peripheral electrode 44 is not limited thereto. The shape of the outer peripheral electrode 44 may be formed in a plan view and depending on the shape of the outer edge 300 of the substrate on which the substrate 2 is epitaxially grown, for example, may be formed in a substantially circular shape. Further, in order to maximize the number of the light-emitting devices 1 that can be obtained from one epitaxial growth substrate 2, a plurality of unit electrodes 48 may be disposed at a predetermined interval along the inner peripheral edge of the outer peripheral electrode of the substantially circular outer peripheral electrode 44.

(Effect of the second embodiment)

According to the method of manufacturing the light-emitting device 1 of the present embodiment, the plurality of unit electrodes and the outer peripheral electrode 44 can be simultaneously formed in the epitaxial growth substrate 2 in the same step. Further, by applying a predetermined voltage to the respective n-type electrode 42 and the outer peripheral electrode 44, the p-type GaN layer 24 and the part of the n-type GaN layer 20 under the respective n-type electrodes 42 can be made. Regional electrical double-conducting. Therefore, the step of etching from the p-type GaN layer 24 to a part of the n-type GaN layer 20 necessary for the manufacturing method of the conventional light-emitting device, and the step of separately forming the p-type electrode and the n-type electrode can be omitted. In the step, the process of the light-emitting device 1 can be greatly simplified. Therefore, the production amount can be improved, the manufacturing time and the manufacturing cost can be greatly reduced as compared with the conventional manufacturing method of the light-emitting device.

Example

Fig. 5 is an enlarged perspective view showing a substrate to which an electrode is attached according to an embodiment of the present invention.

(Structure of substrate 4 with electrodes attached)

The substrate 4 to which the electrodes are attached is obtained by sequentially forming the following portions; the sapphire substrate 10, the buffer layer provided on the sapphire substrate 10, the n-type GaN layer 20 provided on the buffer layer, and the light emitted on the n-type GaN layer 20 The layer 22, the p-type GaN layer 24 provided on the light-emitting layer 22, the contact layer provided on the p-type GaN layer 24, and the electrode provided on the contact layer.

Specifically, a plurality of compound semiconductor layers are grown by MOCVD on the sapphire substrate 10 to obtain an epitaxial growth substrate 2. That is, first, AlN as a buffer layer was grown to 15 nm on the sapphire substrate 10. Next, an n-type GaN layer 20 mainly doped with GaN is doped with Si in a range of 1 to 4 × 10 ¹⁸ (cm ^-3 ) on the buffer layer and grown to about 3000 to 4000 nm. Then, as the light-emitting layer 22, quantum wells composed of In _0.2 Ga _0.8 N/GaN (In _0.2 Ga _0.8 N: 3 nm, GaN: 10 to 12 nm) were grown on the n-type GaN layer 20 by six pairs.

Next, as the p-type GaN layer 24, Mg 1 × 10 ²⁰ (cm ^-3 ) is doped on the light-emitting layer 22 and p-In _0.08 Ga _0.92 N/p-Al _0.3 Ga _0.7 N (p-In _0.08) After the growth of five layers of Ga _0.92 N: 1.7 nm and p-Al _0.3 Ga _0.7 N: 4 nm), the p-GaN layer doped with Mg 5 × 10 ¹⁹ (cm ^-3 ) is grown to 80 to 100 nm. . Then, as a contact layer 24 on the p-type GaN layer doped with ^{Mg 1 × 10 20 (cm -} 3) of the p + -GaN layer is grown 25nm. Thereby, the epitaxial growth substrate 2 can be obtained.

Next, on the contact layer, a circular electrode 43, a ring electrode 41, and an outer peripheral electrode 45 are formed by using a photolithography technique and an etching technique. Specifically, first, 300 nm of ITO was formed by vacuum evaporation on the entire surface of the contact layer. Next, heat treatment was applied to the epitaxial growth substrate 2 after vapor deposition of ITO at 700 ° C for 5 minutes in an N ₂ atmosphere.

Further, in a region where the circular electrode 43, the ring electrode 41, and the outer peripheral electrode 45 are to be formed, a mask formed by a photoresist is formed. Next, by etching with an ITO etching solution, ITO was removed except for the area covered by the mask. Thereby, the substrate 4 to which the electrodes are attached can be obtained.

Further, the circular electrode 43, the ring electrode 41 and the inner periphery of the outer peripheral electrode 45 are concentrically arranged; the diameter of the circular electrode 43 is 200 μm, and the distance from the outer edge of the circular electrode 43 to the inner edge of the ring electrode 41 is 5 μm. . Further, the distance from the outer edge of the ring electrode 41 to the inner edge of the outer peripheral electrode 45 was 20 μm.

(voltage application processing to the substrate 4 to which the electrode is attached)

Fig. 6 shows an IV curve when a voltage of 0 to 10 (V) is applied between the circular electrode and the peripheral electrode.

First, the round electrode 43 is set on the negative side, and the outer peripheral electrode 45 is set on the positive side, and the voltage value is sequentially increased from 0 (V) to about 10 (V), and a voltage is applied to the circular electrode 43 and the peripheral electrode. Between 45. When the voltage applied between the round electrode 43 and the outer peripheral electrode 45 is 4.0 (V), the current flowing between the circular electrode 43 and the outer peripheral electrode 45 is approximately 2.0 E to 4 (A). Further, when the voltage applied between the circular electrode 43 and the peripheral electrode 45 is gradually increased from 4.0 (V), the current flowing between the circular electrode 43 and the peripheral electrode 45 is gradually increased in response to an increase in the voltage.

Fig. 7 shows an IV curve when a voltage of 0 to 80 (V) is applied between the circular electrode and the peripheral electrode.

Similarly to Fig. 6, the round electrode 43 is set on the negative side, and the outer peripheral electrode 45 is set on the positive side, and the voltage value is sequentially increased from 0 (V) to about 80 (V), and a voltage is applied to the circular electrode. 43 is between the peripheral electrode 45. The current flowing between the circular electrode 43 and the outer peripheral electrode 45 is about 1.0E to 3 (A) or less until the applied voltage is about 50 (V). Further, the current applied between the round electrode 43 and the outer peripheral electrode 45 is from about 60 (V) or more to about 80 (V), and the current is rapidly increased. The reason for this is that since a voltage of about 80 (V) is applied between the circular electrode 43 and the peripheral electrode 45, the pn junction between the p-type GaN layer 24 under the circular electrode 43 and the n-type GaN layer 20 is broken, and partial conduction is formed. Part 26.

Fig. 8 shows an IV curve after destruction of the semiconductor under the round electrode.

Next, after a voltage of about 80 (V) is applied between the round electrode 43 and the outer peripheral electrode 45, a voltage (parallel voltage) is again applied between the round electrode 43 and the outer peripheral electrode 45, and the IV characteristic is measured. Before the pn junction between the p-type GaN layer 24 under the round electrode 43 and the n-type GaN layer 20 is broken, the applied voltage is 1.0 (V), and the current flowing between the circular electrode 43 and the outer peripheral electrode 45 is about 0.5E. 4 (A) (Figure 6). On the other hand, after the pn junction is broken, as shown in FIG. 8, when the applied voltage is 1.0 (V), the current flowing between the circular electrode 43 and the outer peripheral electrode 45 is about 1.2E to 2 (A). Further, the substrate 4 with the electrode including the round electrode 43 and the outer peripheral electrode 45 has the same size as the light-emitting element of a general size (for example, a size of about 350 μm), and the round electrode 43 and the outer peripheral electrode 45 are rectifying; In Fig. 8, since the area of the peripheral electrode is very large, rectification is not exhibited.

(Evaluation of characteristics after voltage application processing)

Fig. 9 shows an IV curve when a voltage is applied between the circular electrode and the ring electrode after forming a portion of the conduction portion.

After the partial conductive portion 26 is formed under the circular electrode 43, the circular electrode 43 is set on the negative side, and the ring electrode 41 is set on the positive side, and a voltage is applied to the circle in the range of 0.0 (V) to 5.0 (V). The electrode 43 is between the electrode 43 and the ring electrode 41. At this time, rectification characteristics were observed between the round electrode 43 and the ring electrode 41. Further, when a voltage of about 2.8 (V) or more was applied between the circular electrode 43 and the ring electrode 41, blue light having a peak wavelength of 460 nm was observed. Further, the driving voltage of the substrate 4 system 20 (mA) to which the electrodes are attached is about 3.9 (V).

Fig. 10 shows an IV curve when a voltage is applied between the circular electrode and the ring electrode after forming a portion of the conduction portion.

Referring to Fig. 10, the substrate 4 with electrodes provided in the present embodiment can obtain the same characteristics as the LED-specific IV curve having pn junction. That is, after the partial conduction portion 26 is formed under the circular electrode 43, the circular electrode 43 is set on the negative side, and the ring electrode 41 is set on the positive side; and the forward voltage is applied between the circular electrode 43 and the ring electrode 41. At about 2.8 (V) or more, the voltage increases while the current increases. On the other hand, when a reverse voltage is applied between the circular electrode 43 and the ring electrode 41, almost no current flows until at least -4.0 (V). From this, it is understood that the partial conductive portion 26 is formed only for at least a part of the lower portion of the circular electrode 43.

The above description relates to a case where a voltage is applied between the circular electrode 43 and the outer peripheral electrode 45 to form the partial conductive portion 26; however, a partial conductive portion 26 may be formed by applying a voltage between the circular electrode 43 and the ring electrode 41. Hereinafter, a case where a voltage is applied between the circular electrode 43 and the ring electrode 41 to form the partial conduction portion 26 will be described.

(voltage application processing to the substrate 4 to which the electrode is attached)

Figure 11 shows an IV curve when a voltage of -10 (V) to 10 (V) is applied between the round electrode and the ring electrode.

First, the round electrode 43 is set on the negative side, and the ring electrode 41 is set on the positive side, and the voltage value is sequentially increased from -10 (V) to about 10 (V), and a voltage is applied to the circular electrode 43 and the ring. Between the electrodes 41. Under the voltage application conditions, the pn junction between the p-type GaN layer 24 under the round electrode 43 and the n-type GaN layer 20 is not broken, and almost no current flows between the round electrode 43 and the ring electrode 41 have been confirmed.

Figure 12 shows the IV curve when a voltage of 0 to 47 (V) is applied between the round electrode and the ring electrode.

Similarly to Fig. 11, the round electrode 43 is set on the negative side, and the ring electrode 41 is set on the positive side, and the voltage value is sequentially increased from 0 (V) to about 47 (V), and a voltage is applied to the circular electrode. 43 is between the ring electrode 41. The current flowing between the circular electrode 43 and the ring electrode 41 is approximately 2.00E to 3 (A) or less until the applied voltage is approximately 50 (V). Further, the current applied between the round electrode 43 and the ring electrode 41 is from about 40 (V) or more to about 47 (V), and the current is rapidly increased. The reason for this is that since a voltage of about 47 (V) is applied between the circular electrode 43 and the ring electrode 41, the pn junction between the p-type GaN layer 24 under the circular electrode 43 and the n-type GaN layer 20 is broken, and partial conduction is formed. Part 26.

Fig. 13 shows an IV curve after destruction of the semiconductor under the round electrode.

Next, between the round electrode 43 and the ring electrode 41, the voltage value is sequentially increased from -10 (V) to about 10 (V) in the same manner as before the destruction, and a voltage is applied to the circular electrode 43 and the ring electrode 41. between. Under the voltage application condition after the pn junction was broken, the applied voltage was +2.7 (V); and the current flowed between the round electrode 43 and the ring electrode 41, and the current value was increased as the applied voltage was increased. The applied voltage is 10 (V); and the current flowing between the circular electrode 43 and the ring electrode 41 is 7.50E to 3 (A).

The embodiments and examples of the present invention have been described above, but the embodiments and examples described above do not limit the invention according to the scope of the claims. Further, it should be noted that all combinations of the features described in the embodiments and the examples are not essential to the method for solving the problems of the invention.

1‧‧‧Lighting device

2‧‧‧ epitaxial growth substrate

3, 4‧‧‧The substrate with the electrode

10‧‧‧Sapphire substrate

20‧‧‧n-type GaN layer

22‧‧‧Lighting layer

24‧‧‧p-type GaN layer

25‧‧‧p-type GaN surface

26‧‧‧Parts of the Ministry of Conduct

40‧‧‧p type electrode

41‧‧‧ ring electrode

42‧‧‧n type electrode

43‧‧‧ Round electrode

44, 45‧‧‧ peripheral electrodes

46‧‧‧ electrodes

48‧‧‧Unit electrode

50, 52‧‧‧ probe

300‧‧‧Shelf outer edge

402‧‧‧ peripheral electrode inner edge

Fig. 1 is a schematic perspective view of a light-emitting device according to a first embodiment.

Fig. 2 is a longitudinal sectional view showing a light-emitting device according to the first embodiment.

3(a) to 3(d) are explanatory views showing the process of the light-emitting device according to the first embodiment.

Fig. 4 is a plan view showing a substrate to which an electrode is attached according to the second embodiment.

Fig. 5 is an enlarged perspective view showing a substrate to which an electrode is attached according to an embodiment.

Fig. 6 is an IV curve when a voltage of 0 to 10 (V) is applied between the circular electrode and the peripheral electrode according to the embodiment.

Figure 7 is an IV curve when a voltage of 0 to 80 (V) is applied between the circular electrode and the peripheral electrode according to the embodiment.

Fig. 8 is an IV curve after the semiconductor junction under the round electrode is broken according to the embodiment.

Figure 9 is an IV curve when a voltage is applied between a circular electrode and a ring electrode after forming a portion of the conductive portion in accordance with an embodiment.

Figure 10 is an IV curve when a voltage is applied between a circular electrode and a ring electrode after forming a portion of the conductive portion in accordance with an embodiment.

Figure 11 is an IV curve when a voltage of -10 to 10 (V) is applied to the round electrode and the ring electrode according to the embodiment.

Figure 12 is an IV curve when a voltage of 0 to 47 (V) is applied between the circular electrode and the ring electrode according to the embodiment. curve.

Figure 13 is an IV curve after the semiconductor junction under the round electrode is broken according to an embodiment.

1. . . Illuminating device

10. . . Sapphire substrate

20. . . N-type GaN layer

twenty two. . . Luminous layer

twenty four. . . P-type GaN layer

26. . . Partial conduction

40. . . P-type electrode

42. . . N-type electrode

50, 52. . . Probe

Claims (5)

A light-emitting device comprising: a first semiconductor layer of a first conductivity type; a second semiconductor layer of a second conductivity type, wherein the first semiconductor layer is provided thereon, and the second conductivity type is different from the first a conductive type; a first electrode is disposed on the first semiconductor layer; a second electrode is provided on the first semiconductor layer separately from the first electrode; and a partial conductive portion is formed under the second electrode And the second electrode and the second semiconductor layer are electrically bidirectional. The light-emitting device of claim 1, wherein the portion of the conductive portion is formed by applying a predetermined voltage between the first electrode and the second electrode. The light-emitting device of claim 1 or 2, wherein the area of the second electrode is smaller than the area of the first electrode. The light-emitting device according to claim 1 or 2, wherein the material for forming the first electrode is the same as the material for forming the second electrode. The light-emitting device of claim 3, wherein the material for forming the first electrode is the same as the material for forming the second electrode.