JP5422712B2 - Bar-shaped structure light emitting device, backlight, illumination device and display device - Google Patents

Description

  The present invention relates to a rod-shaped structure light emitting element, a backlight, a lighting device, and a display device.

  Conventionally, as a light emitting element having a rod-shaped structure, there is a nano-order size light-emitting element in which a heterostructure is formed by a rod-shaped core portion made of a compound semiconductor and a cylindrical shell portion made of a compound semiconductor surrounding the core portion (for example, JP, 2008-235443, A (patent documents 1) reference). In this light emitting device, the core part itself becomes an active layer, and electrons and holes injected from the outer peripheral surface recombine in the core part to emit light.

  Using a manufacturing method similar to that of the light-emitting element, a pn junction between the outer peripheral surface of the core portion and the inner peripheral surface of the shell portion has a core portion made of an n-type semiconductor and a shell portion made of a p-type semiconductor. In the case of manufacturing a rod-shaped structure light emitting device that emits light by recombination of electrons and holes, there is a problem that it is difficult to connect the core portion and the electrode because only the both end surfaces are exposed.

JP 2008-235443 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fine rod-shaped structure light emitting element with high light emission efficiency that can easily connect electrodes with a simple configuration.

  Another object of the present invention is to provide a backlight which can be reduced in thickness and weight by using the light emitting element having a rod-like structure and has high luminous efficiency and power saving.

  Another object of the present invention is to provide an illuminating device that can be reduced in thickness and weight by using the light emitting element with a rod-like structure, has high luminous efficiency, and saves power.

  Another object of the present invention is to provide a display device that can be reduced in thickness and weight by using the light emitting element with a rod-like structure, has high luminous efficiency, and saves power.

In order to solve the above problems, the rod-shaped structure light emitting device of the present invention is
A rod-shaped first conductive type semiconductor core;
A semiconductor layer of a second conductivity type formed so as to cover the semiconductor core;
A transparent electrode formed so as to cover the semiconductor layer and not to be electrically connected to the semiconductor core;
The outer peripheral surface of a part of the semiconductor core is exposed ,
The transparent electrode is formed so as not to cover an exposed portion of the outer peripheral surface of the semiconductor core .

  According to the above configuration, the second conductive type semiconductor layer is formed so as to cover the rod-shaped first conductive type semiconductor core and to expose a part of the outer peripheral surface of the semiconductor core. Even in a fine rod-shaped structure light emitting device of size or nano-order size, it becomes possible to connect the exposed part of the semiconductor core to one electrode and connect the other electrode to the part of the semiconductor layer covering the semiconductor core . In this rod-shaped structure light emitting device, one electrode is connected to the exposed portion of the semiconductor core, the other electrode is connected to the semiconductor layer, and electrons are formed at the pn junction between the outer peripheral surface of the semiconductor core and the inner peripheral surface of the semiconductor layer. Light is emitted from the pn junction by passing a current between the electrodes so that recombination of the hole and the hole occurs. In this rod-shaped structure light emitting device, the light emitting region is widened by emitting light from the entire circumference of the semiconductor core covered with the semiconductor layer, so that the light emission efficiency is high. Therefore, it is possible to realize a fine rod-shaped light emitting element with high luminous efficiency that can be easily connected to an electrode with a simple configuration. Since this rod-shaped structure light emitting element is not integrated with the substrate, the degree of freedom of mounting on the device is high.

  Also, by forming a transparent electrode so as to cover the semiconductor layer, the semiconductor layer is connected to the electrode via the transparent electrode, thereby forming a wide current path without current concentration and bias in the electrode connection portion. Thus, the entire device can emit light, and the light emission efficiency is further improved.

  Here, the fine rod-shaped structure light-emitting element is, for example, a micro-order size having a diameter of 1 μm and a length of 10 μm, or a nano-order size element having a diameter or length of less than 1 μm. In addition, the rod-shaped structure light emitting element can reduce the amount of semiconductor used, can reduce the thickness and weight of the device using the light emitting element, and has high luminous efficiency and low power consumption, a lighting device, a display device, and the like Can be realized.

Moreover, in the rod-shaped structure light emitting device of one embodiment,
The outer peripheral surface of one end side of the semiconductor core is exposed.

  According to the embodiment, the outer peripheral surface on one end side of the semiconductor core is exposed, so that one electrode is connected to the exposed portion of the outer peripheral surface on one end side of the semiconductor core, and the semiconductor on the other end side of the semiconductor core is connected. Electrodes can be connected to the layers, and the electrodes can be connected to both ends separately, so that the electrodes connected to the semiconductor layer and the exposed portions of the semiconductor core can be easily prevented from being short-circuited.

Moreover, in the rod-shaped structure light emitting device of one embodiment,
The end surface of the other end side of the semiconductor core is covered with the semiconductor layer.

  According to the above-described embodiment, the semiconductor core is short-circuited to the portion of the semiconductor layer that covers the end surface on the side opposite to the exposed region of the semiconductor core by covering the end surface of the other end side of the semiconductor core with the semiconductor layer. Electrode can be connected easily. This makes it possible to easily connect the electrodes to both ends of the fine rod-shaped structure light emitting element.

Moreover, in the rod-shaped structure light emitting device of one embodiment,
In the semiconductor layer, the axial thickness of the portion covering the end surface on the other end side of the semiconductor core is larger than the radial thickness of the portion covering the outer peripheral surface of the semiconductor core.

  According to the above embodiment, the electrode connected to the semiconductor layer covering the end face on the other end side of the semiconductor core can be connected to the semiconductor layer without overlapping with the semiconductor core. Can be prevented, and the light extraction efficiency of the entire side surface of the semiconductor core can be improved. Or even if the electrode connected to the semiconductor layer that covers the end face of the other end of the semiconductor core overlaps the semiconductor core, the amount of overlap can be reduced, improving the light extraction efficiency it can. Further, the semiconductor layer has a thickness in the axial direction of a portion covering the end face on the other end side of the semiconductor core rather than a thickness in a radial direction of a portion covering the outer peripheral surface of the semiconductor core. The resistance of the portion of the semiconductor layer covering the end face is increased, the light emission is not concentrated on the other end side of the semiconductor core, the light emission in the side surface region of the semiconductor core can be enhanced, and the end face on the other end side of the semiconductor core is covered. Leakage current in the semiconductor layer portion can be suppressed.

Moreover, in the rod-shaped structure light emitting device of one embodiment,
A quantum well layer was formed between the semiconductor core and the semiconductor layer.

  According to the embodiment, by forming the quantum well layer between the semiconductor core and the semiconductor layer, the light emission efficiency can be further improved by the quantum confinement effect of the quantum well layer.

Moreover, in the rod-shaped structure light emitting device of one embodiment,
While the outer peripheral surface of one end side of the semiconductor core is exposed,
The end face on the other end side of the semiconductor core is covered with the semiconductor layer,
Comprising a quantum well layer formed between the semiconductor core and the semiconductor layer;
In the quantum well layer, the axial thickness of the portion covering the end face on the other end side of the semiconductor core is thicker than the radial thickness of the portion covering the outer peripheral surface of the semiconductor core.

  According to the above embodiment, the electrode connected to the semiconductor layer covering the end face on the other end side of the semiconductor core can be connected to the semiconductor layer without overlapping with the semiconductor core. Can be prevented, and the light extraction efficiency of the entire side surface of the semiconductor core can be improved. Or even if the electrode connected to the semiconductor layer that covers the end face of the other end of the semiconductor core overlaps the semiconductor core, the amount of overlap can be reduced, improving the light extraction efficiency it can. The quantum well layer has a thickness in the axial direction of a portion covering the end face on the other end side of the semiconductor core rather than a thickness in a radial direction of a portion covering the outer peripheral surface of the semiconductor core. The electric field concentration can be reduced, the breakdown voltage can be improved, the lifetime of the light emitting element can be improved, and the leakage current in the quantum well layer covering the end face on the other end side of the semiconductor core can be suppressed.

Moreover, in the rod-shaped structure light emitting device of one embodiment,
The semiconductor core is made of an n-type semiconductor,
The semiconductor layer is made of a p-type semiconductor.

  In a configuration in which a pn junction is formed between the outer peripheral surface of a semiconductor core made of an n-type semiconductor and the inner peripheral surface of a semiconductor layer made of a p-type semiconductor, the semiconductor layer made of a p-type semiconductor hardly raises the impurity concentration. Since the resistance is large, when an electrode is connected to a part of the semiconductor layer, the current is concentrated and biased at the electrode connection part, and the entire light emission is inhibited. However, according to the above embodiment, in the rod-shaped structure light emitting device in which the semiconductor layer made of the p-type semiconductor is formed so as to cover the semiconductor core made of the n-type semiconductor, the transparent electrode is formed so as to cover substantially the entire semiconductor layer. By connecting the semiconductor layer to the electrode through the transparent electrode, the current does not concentrate on the electrode connection portion and is not biased, and a wide current path can be formed, allowing the entire device to emit light. Efficiency is further improved.

In the backlight of the present invention,
Any one of the above rod-shaped structure light emitting elements is provided.

  According to the above configuration, by using the rod-shaped structure light emitting element, it is possible to realize a backlight that can be reduced in thickness and weight, has high luminous efficiency, and saves power.

In the lighting device of the present invention,
Any one of the above rod-shaped structure light emitting elements is provided.

  According to the said structure, by using the said rod-shaped structure light emitting element, the illuminating device which can be reduced in thickness and weight, and is high in luminous efficiency and power saving is realizable.

In the display device of the present invention,
Any one of the above rod-shaped structure light emitting elements is provided.

  According to the above configuration, by using the light emitting element with a rod-like structure, a display device that can be reduced in thickness and weight and has high luminous efficiency and low power consumption can be realized.

  As is apparent from the above, according to the rod-shaped structure light emitting device of the present invention, it is possible to realize a fine rod-shaped structure light emitting device with high luminous efficiency that can be easily connected to an electrode with a simple configuration.

  Further, according to the backlight of the present invention, it is possible to realize a backlight that can be reduced in thickness and weight, has high luminous efficiency, and saves power.

  Further, according to the lighting device of the present invention, it is possible to realize a lighting device that can be reduced in thickness and weight, has high luminous efficiency, and saves power.

  Further, according to the display device of the present invention, it is possible to realize a display device that can be reduced in thickness and weight, has high luminous efficiency, and saves power.

FIG. 1 is a perspective view of a rod-shaped structure light emitting device according to a first embodiment of the present invention. FIG. 2 is a perspective view of a rod-shaped structure light emitting device according to a second embodiment of the present invention. FIG. 3 is a perspective view of a rod-shaped structure light emitting device according to a third embodiment of the present invention. FIG. 4 is a perspective view of a rod-shaped structure light emitting device according to a fourth embodiment of the present invention. FIG. 5 is a sectional view of the rod-shaped structure light emitting device. FIG. 6 is a cross-sectional view for explaining electrode connection of the rod-shaped structure light emitting element. FIG. 7 is a perspective view of another bar-shaped light emitting element having a hexagonal cross section. FIG. 8 is a perspective view of another bar-shaped structure light-emitting element having a hexagonal cross section. FIG. 9 is a perspective view of another bar-shaped light emitting element having a hexagonal cross section. FIG. 10 is a perspective view of another bar-shaped structure light-emitting element having a hexagonal cross section. FIG. 11 is a sectional view of a rod-shaped structure light emitting device according to a fifth embodiment of the present invention. FIG. 12 is a schematic cross-sectional view of the main part of the rod-shaped structure light emitting device. FIG. 13 is a schematic cross-sectional view of a main part of a bar-shaped light emitting element of a comparative example. FIG. 14 is a sectional view of a rod-shaped structure light emitting device according to the sixth embodiment of the present invention. FIG. 15 is a schematic cross-sectional view of the main part of the rod-shaped structure light emitting device. FIG. 16 is a schematic cross-sectional view of a main part of a bar-shaped light emitting element of a comparative example. FIG. 17A is a process diagram of a method for manufacturing a rod-shaped structured light emitting element according to the seventh embodiment of the present invention. FIG. 17B is a process diagram of the manufacturing method of the rod-shaped structure light emitting element following FIG. 17A. FIG. 17C is a process drawing of the manufacturing method of the rod-shaped structure light emitting element following FIG. 17B. FIG. 17D is a process drawing of the manufacturing method of the rod-shaped structure light emitting element following FIG. 17C. FIG. 17E is a process diagram of the manufacturing method of the rod-shaped structure light emitting element following FIG. 17D. FIG. 18A is a process drawing of the method for manufacturing the rod-shaped structure light emitting device of the eighth embodiment of the present invention. FIG. 18B is a process diagram of the manufacturing method of the rod-shaped structure light emitting element following FIG. 18A. FIG. 18C is a process diagram of the manufacturing method of the rod-shaped structure light emitting element following FIG. 18B. FIG. 18D is a process diagram of the manufacturing method of the rod-shaped structure light emitting element following FIG. 18C. FIG. 18E is a process drawing of the manufacturing method of the rod-shaped structure light emitting element following FIG. 18D. FIG. 19A is a process diagram of a method for manufacturing a rod-shaped structured light emitting element according to the ninth embodiment of the present invention. FIG. 19B is a process diagram of the manufacturing method of the rod-shaped structure light emitting element following FIG. 19A. FIG. 19C is a process diagram of the manufacturing method of the rod-shaped structure light emitting element following FIG. 19B. FIG. 19D is a process diagram of the manufacturing method of the rod-shaped structure light emitting element following FIG. 19C. FIG. 19E is a process drawing of the manufacturing method of the rod-shaped structure light emitting element following FIG. 19D. FIG. 20 is a plan view of an insulating substrate used in a backlight, a lighting device, and a display device including a bar-shaped light emitting element according to the tenth embodiment of the present invention. FIG. 21 is a schematic sectional view taken along line XXI-XXI in FIG. FIG. 22 is a diagram for explaining the principle of arranging the rod-shaped structure light emitting elements. FIG. 23 is a diagram for explaining potentials applied to the electrodes when the rod-shaped structure light emitting elements are arranged. FIG. 24 is a plan view of an insulating substrate on which the rod-shaped structure light emitting elements are arranged. FIG. 25 is a plan view of the display device. FIG. 26 is a circuit diagram of a main part of the display unit of the display device.

  Hereinafter, the rod-shaped structure light emitting element, backlight, illumination device, and display device of the present invention will be described in detail with reference to the illustrated embodiments. In this embodiment, the first conductivity type is n-type and the second conductivity type is p-type. However, the first conductivity type may be p-type and the second conductivity type may be n-type.

[First Embodiment]
FIG. 1 is a perspective view of a rod-shaped structure light emitting device according to a first embodiment of the present invention. As shown in FIG. 1, the rod-shaped structure light emitting device of the first embodiment has a semiconductor core 11 made of a rod-shaped n-type GaN with a substantially circular cross section and a p formed so as to cover a part of the semiconductor core 11. And a semiconductor layer 12 made of type GaN. The semiconductor core 11 has an exposed portion 11a where the outer peripheral surface on one end side is exposed. Further, the end surface on the other end side of the semiconductor core 11 is covered with the semiconductor layer 12.

  The rod-shaped structure light emitting device is manufactured as follows.

First, a mask having a growth hole is formed on a substrate made of n-type GaN. For the mask, a material that can be selectively etched with respect to the semiconductor core 11 and the semiconductor layer 12 such as silicon oxide (SiO ₂ ) or silicon nitride (Si ₃ N ₄ ) is used. The growth hole can be formed by a known lithography method and dry etching method used in a normal semiconductor process.

Next, using a MOCVD (Metal Organic Chemical Vapor Deposition) apparatus, an n-type GaN crystal is grown on the substrate exposed by the growth hole of the mask to form the rod-shaped semiconductor core 11. The temperature of the MOCVD apparatus is set to about 950 ° C., trimethylgallium (TMG) and ammonia (NH ₃ ) are used as growth gases, silane (SiH ₃ ) is used for supplying n-type impurities, and hydrogen (H ₃ ), an n-type GaN semiconductor core having Si as an impurity can be grown. At this time, the diameter of the semiconductor core 11 to be grown can be determined by the diameter of the growth hole of the mask.

Next, a semiconductor layer made of p-type GaN is formed on the entire surface of the substrate so as to cover the rod-shaped semiconductor core 11. By setting the temperature of the MOCVD apparatus to about 960 ° C., using trimethylgallium (TMG) and ammonia (NH ₃ ) as growth gases and biscyclopentadienylmagnesium (Cp ₂ Mg) for supplying p-type impurities, It is possible to grow p-type GaN having (Mg) as an impurity.

Next, the region excluding the portion of the semiconductor layer that covers the semiconductor core and the mask are removed by lift-off, and the outer peripheral surface of the rod-shaped semiconductor core 11 on the substrate side is exposed to form an exposed portion 11a. In this state, the end surface of the semiconductor core 11 opposite to the substrate is covered with the semiconductor layer 12. When the mask is made of silicon oxide (SiO ₂ ) or silicon nitride (Si ₃ N ₄ ), a semiconductor core portion that easily covers the semiconductor core and the semiconductor core by using a solution containing hydrofluoric acid (HF) The mask can be etched without affecting the mask, and the semiconductor layer on the mask together with the mask (region excluding the portion of the semiconductor layer covering the semiconductor core) can be removed by lift-off. In this embodiment, the length of the exposed portion 11a of the semiconductor core 11 is determined by the thickness of the removed mask. In the exposure process of this embodiment, lift-off is used, but a part of the semiconductor core may be exposed by etching.

  Next, the substrate is immersed in an isopropyl alcohol (IPA) aqueous solution, and the substrate is vibrated along the plane of the substrate using ultrasonic waves (for example, several tens of kHz). Stress is applied to the semiconductor core 11 covered with the semiconductor layer 12 so that the close base is bent, and the semiconductor core 11 covered with the semiconductor layer 12 is separated from the substrate.

  In this way, a fine rod-shaped structure light emitting device separated from the substrate made of n-type GaN can be manufactured.

  Furthermore, in the rod-shaped structure light emitting element, the semiconductor layer 12 grows crystal outward from the outer peripheral surface of the semiconductor core 11 in the radial direction, the radial growth distance is short, and the defects escape outward, so the semiconductor layer 12 with few crystal defects. Thus, the semiconductor core 11 can be covered. Therefore, it is possible to realize a rod-shaped structure light emitting device with good characteristics.

  According to the rod-shaped structure light emitting device having the above-described configuration, the semiconductor layer 12 made of p-type GaN so as to cover the semiconductor core 11 made of rod-shaped n-type GaN and to expose a part of the outer peripheral surface of the semiconductor core 11. The semiconductor layer 12 portion that covers the semiconductor core 11 by connecting the exposed portion 11a of the semiconductor core 11 to the n-side electrode, even in a micro-order size or nano-order size fine rod-shaped structure light emitting device. It is possible to connect the p-side electrode. In this rod-shaped structure light emitting element, an n-side electrode is connected to the exposed portion 11 a of the semiconductor core 11, and a p-side electrode is connected to the semiconductor layer 12, so that the outer peripheral surface of the semiconductor core 11 and the inner peripheral surface of the semiconductor layer 12 are By flowing a current from the p-side electrode to the n-side electrode so that recombination of electrons and holes occurs at the pn junction, light is emitted from the pn junction. In this rod-shaped structure light emitting element, the light emission region is widened by emitting light from the entire circumference of the semiconductor core 11 covered with the semiconductor layer 12, and thus the light emission efficiency is high. Accordingly, it is possible to realize a fine rod-shaped light emitting element with high luminous efficiency that can be easily connected to an electrode with a simple configuration. Moreover, since the said rod-shaped structure light emitting element is not integrated with a board | substrate, the freedom degree of mounting to an apparatus is high.

  Here, the fine rod-shaped structure light emitting device is, for example, a micro-order size having a diameter of 1 μm and a length of 10 μm to 30 μm, or a nano-order size device having a diameter or length of less than 1 μm. In addition, the rod-shaped structure light emitting element can reduce the amount of semiconductor used, can reduce the thickness and weight of the device using the light emitting element, and has high luminous efficiency and low power consumption, a lighting device, a display device, and the like Can be realized.

  In addition, the outer peripheral surface on one end side of the semiconductor core 11 is exposed to, for example, about 1 μm to 5 μm in the axial direction, so that one electrode is connected to the exposed portion 11a of the outer peripheral surface on one end side of the semiconductor core 11; Electrodes can be connected to the semiconductor layer 12 on the other end side of the semiconductor core 11, electrodes can be connected to both ends separately, and it is easy for the electrode connected to the semiconductor layer 12 and the exposed portion of the semiconductor core 11 to be short-circuited. Can be prevented.

  Moreover, the semiconductor core 11 is short-circuited to the semiconductor layer 11 covering the end surface opposite to the exposed portion 11 a of the semiconductor core 11 by covering the end surface of the other end side of the semiconductor core 11 with the semiconductor layer 12. The p-side electrode can be easily connected without causing it to occur. This makes it possible to easily connect the electrodes to both ends of the fine rod-shaped structure light emitting element.

  Further, the outer peripheral surface of the region covered with the semiconductor layer 12 of the semiconductor core 11 and the outer peripheral surface of the exposed region of the semiconductor core 11 are continuous, so that the exposed region of the semiconductor core 11 is the outer diameter of the semiconductor layer 12. Since it is thinner, it becomes easier to bend on the substrate side of the exposed region of the semiconductor core 11 formed so as to stand on the substrate in the manufacturing process, thereby facilitating manufacture.

[Second Embodiment]
FIG. 2 is a perspective view of a rod-shaped structure light emitting device according to a second embodiment of the present invention. As shown in FIG. 2, the rod-shaped structure light emitting device of the second embodiment includes a semiconductor core 21 made of a rod-shaped n-type GaN having a substantially circular cross section and a p formed so as to cover a part of the semiconductor core 21. A quantum well layer 22 made of type InGaN and a semiconductor layer 23 made of p type GaN formed so as to cover the quantum well layer 22 are provided. The semiconductor core 21 is formed with an exposed portion 21a where the outer peripheral surface on one end side is exposed. The end face on the other end side of the semiconductor core 21 is covered with the quantum well layer 22 and the semiconductor layer 23.

  In the rod-shaped structure light emitting device of the second embodiment, similarly to the rod-shaped structure light emitting device of the first embodiment, an n-type GaN crystal is grown on a substrate made of n-type GaN using a MOCVD apparatus, thereby forming a rod-shaped semiconductor. A core 21 is formed.

  The rod-shaped structure light emitting device of the second embodiment has the same effect as the rod-shaped structure light emitting device of the first embodiment.

Further, by forming the quantum well layer 22 between the semiconductor core 21 and the semiconductor layer 23, the light emission efficiency can be further improved by the quantum confinement effect of the quantum well layer 22. After growing the n-type GaN semiconductor core in the MOCVD apparatus as described above, the set temperature is changed from 600 ° C. to 800 ° C. according to the emission wavelength, nitrogen (N ₂ ) as the carrier gas, and TMG as the growth gas. By supplying NH ₃ and trimethylindium (TMI), the InGaN quantum well layer 22 can be formed on the n-type GaN semiconductor core 21. Thereafter, the set temperature is further set to 960 ° C., and as described above, TMG and NH ₃ are used as the growth gas, and Cp ₂ Mg is used for supplying the p-type impurity, thereby forming the semiconductor layer 23 made of p-type GaN. can do. The quantum well layer may include a p-type AlGaN layer as an electron blocking layer between the InGaN layer and the p-type GaN layer, or a multiple layer in which GaN barrier layers and InGaN quantum well layers are alternately stacked. It may be a quantum well structure.

[Third Embodiment]
FIG. 3 is a perspective view of a rod-shaped structure light emitting device according to a third embodiment of the present invention. As shown in FIG. 3, the rod-shaped structure light emitting device of the third embodiment has a semiconductor core 11 made of a rod-shaped n-type GaN having a substantially circular cross section and a p formed so as to cover a part of the semiconductor core 11. A semiconductor layer 12 made of type GaN and a transparent electrode 13 formed so as to cover the semiconductor layer 12 are provided. The semiconductor core 11 has an exposed portion 11a where the outer peripheral surface on one end side is exposed. Further, the end face on the other end side of the semiconductor core 11 is covered with the semiconductor layer 12 and the transparent electrode 13. The transparent electrode 13 is made of ITO (indium tin oxide) having a thickness of 200 nm. The ITO film can be formed by vapor deposition or sputtering. After forming the ITO film, the contact resistance between the semiconductor layer 12 made of p-type GaN and the transparent electrode 13 made of ITO can be reduced by performing heat treatment at 500 ° C. to 600 ° C. The transparent electrode is not limited to this, and an Ag / Ni laminated metal film having a thickness of 5 nm, for example, may be used. Vapor deposition or sputtering can be used for film formation. In order to further reduce the resistance of the electrode layer, an Ag / Ni laminated metal film may be laminated on the ITO film.

  In the rod-shaped structure light emitting device of the third embodiment, similarly to the rod-shaped structure light emitting device of the first embodiment, an n-type GaN crystal is grown on a substrate made of n-type GaN using a MOCVD apparatus, thereby forming a rod-shaped semiconductor. The core 11 is formed.

  The rod-shaped structure light emitting device of the third embodiment has the same effect as the rod-shaped structure light emitting device of the first embodiment.

  Further, by forming the transparent electrode 13 so as to cover substantially the entire semiconductor layer 12, the current is concentrated and biased in the electrode connecting portion by connecting the semiconductor layer 12 to the electrode through the transparent electrode 13. Therefore, a wide current path can be formed, and the entire device can emit light, further improving the light emission efficiency. In particular, in the configuration of a semiconductor core made of an n-type semiconductor and a semiconductor layer made of a p-type semiconductor, the semiconductor layer made of a p-type semiconductor has a large resistance while it is difficult to increase the impurity concentration. The entire device can emit light, and the light emission efficiency is further improved.

[Fourth Embodiment]
FIG. 4 is a perspective view of a rod-shaped structure light emitting device according to the fourth embodiment of the present invention. As shown in FIG. 4, the rod-shaped structure light emitting device of the fourth embodiment has a semiconductor core 21 made of a rod-shaped n-type GaN having a substantially circular cross section and a p formed so as to cover a part of the semiconductor core 21. A quantum well layer 22 made of type InGaN, a semiconductor layer 23 made of p-type GaN so as to cover the quantum well layer 22, and a transparent electrode 24 formed so as to cover the semiconductor layer 23. Yes. The semiconductor core 21 is formed with an exposed portion 21a where the outer peripheral surface on one end side is exposed. Further, as shown in the cross-sectional view of FIG. 5, the end face on the other end side of the semiconductor core 21 is covered with the quantum well layer 22, the semiconductor layer 23, and the transparent electrode 24. Thereby, by connecting an electrode (or wiring) to the end of the transparent electrode 24 opposite to the exposed portion 21a of the semiconductor core 21, it is possible to easily prevent the electrode and the semiconductor core 21 from being short-circuited. Since the electrode (or wiring) connected to the transparent electrode 24 can be thick or the sectional area can be increased, heat can be efficiently radiated through the electrode (or wiring).

  Further, as shown in FIG. 6, the rod-shaped structure light emitting element has an n-side electrode 25 connected to the exposed portion 21 a of the semiconductor core 21 and a p-side electrode 26 connected to the transparent electrode 24 on the other end side. Since the p-side electrode 26 is connected to the end of the transparent electrode 24, the area where the light emitting region is blocked by the electrode can be minimized, and the light extraction efficiency can be increased.

  In the rod-shaped structure light emitting device of the fourth embodiment, similarly to the rod-shaped structure light emitting device of the first embodiment, an n-type GaN crystal is grown on a substrate made of n-type GaN using a MOCVD apparatus, thereby forming a rod-shaped semiconductor. A core 21 is formed.

  The rod-shaped structure light emitting device of the fourth embodiment has the same effect as the rod-shaped structure light emitting device of the second embodiment.

  Further, by forming the transparent electrode 24 so as to cover substantially the entire semiconductor layer 23, the semiconductor layer 23 is connected to the p-side electrode 26 via the transparent electrode 24, so that current is concentrated on the electrode connection portion. Therefore, a wide current path can be formed and the entire device can emit light, further improving the light emission efficiency. In particular, in the configuration of a semiconductor core made of an n-type semiconductor and a semiconductor layer made of a p-type semiconductor, the semiconductor layer made of a p-type semiconductor has a large resistance while it is difficult to increase the impurity concentration. The entire device can emit light, and the light emission efficiency is further improved.

  In the first to fourth embodiments, Si-doped n-type GaN and Mg-doped p-type GaN are used. However, impurities doped in GaN are not limited thereto. Ge can be used for the n-type, and Zn can be used for the p-type.

  In the first to fourth embodiments, the rod-shaped structure light emitting device in which the semiconductor cores 11 and 21 having a substantially circular cross section are covered with a semiconductor layer or a quantum well layer has been described. The present invention may be applied to a rod-shaped structure light emitting device in which a semiconductor layer, a quantum well layer, or the like is coated on a polygonal rod-shaped semiconductor core. The n-type GaN has hexagonal crystal growth, and a substantially hexagonal columnar semiconductor core can be obtained by growing the substrate in the direction perpendicular to the substrate surface in the c-axis direction. Although depending on the growth conditions such as the growth direction and growth temperature, when the diameter of the semiconductor core to be grown is as small as several tens to several hundreds of nanometers, the cross section tends to be almost circular, and the diameter is 0.5 μm. When the thickness is increased from about a few μm, it tends to be easy to grow the cross section in a substantially hexagonal shape.

  For example, as shown in FIG. 7, a semiconductor core 31 made of a rod-shaped n-type GaN having a substantially hexagonal cross section, and a semiconductor layer 32 made of p-type GaN formed so as to cover a part of the semiconductor core 31. I have. The semiconductor core 31 has an exposed portion 31a where the outer peripheral surface on one end side is exposed. Further, the end surface on the other end side of the semiconductor core 31 is covered with the semiconductor layer 32.

  Further, as shown in FIG. 8, a semiconductor core 41 made of a rod-shaped n-type GaN having a substantially hexagonal cross section, a quantum well layer 42 formed so as to cover a part of the semiconductor core 41, and the quantum well layer And a semiconductor layer 43 made of p-type GaN so as to cover 42. The semiconductor core 41 has an exposed portion 41a where the outer peripheral surface on one end side is exposed. Further, the end face on the other end side of the semiconductor core 41 is covered with the quantum well layer 42 and the semiconductor layer 43.

  As shown in FIG. 9, a semiconductor core 31 made of a rod-shaped n-type GaN with a substantially circular cross section, a semiconductor layer 32 made of p-type GaN formed so as to cover a part of the semiconductor core 31, and the above And a transparent electrode 33 made of ITO formed so as to cover the semiconductor layer 32. The semiconductor core 31 has an exposed portion 31a where the outer peripheral surface on one end side is exposed. Further, the end surface on the other end side of the semiconductor core 31 is covered with the semiconductor layer 32 and the transparent electrode 33.

  Also, as shown in FIG. 10, a semiconductor core 41 made of a rod-shaped n-type GaN with a substantially circular cross section, a quantum well layer 42 made of p-type InGaN formed so as to cover a part of the semiconductor core 41, A semiconductor layer 43 made of p-type GaN formed so as to cover the quantum well layer 42 and a transparent electrode 44 made of ITO formed so as to cover the semiconductor layer 43 are provided. The semiconductor core 41 has an exposed portion 41a where the outer peripheral surface on one end side is exposed. As shown in FIG. 5, the end face on the other end side of the semiconductor core 41 is covered with a quantum well layer 42, a semiconductor layer 43, and a transparent electrode 44.

[Fifth Embodiment]
FIG. 11 shows a cross-sectional view of a rod-shaped structure light emitting device according to the fifth embodiment of the present invention. As shown in FIG. 11, the rod-shaped structure light emitting device of the fifth embodiment includes a semiconductor core 51 made of a rod-shaped n-type GaN having a substantially circular cross section and a p formed so as to cover a part of the semiconductor core 51. And a semiconductor layer 52 made of type GaN. The semiconductor core 51 has an exposed portion 51a where the outer peripheral surface on one end side is exposed. The end surface on the other end side of the semiconductor core 51 is covered with the semiconductor layer 52.

  The semiconductor layer 52 is formed such that the axial thickness of the portion 52a covering the end face on the other end side of the semiconductor core 51 is thicker than the radial thickness of the portion 52b covering the outer peripheral surface of the semiconductor core 51. Yes.

  FIG. 12 is a schematic cross-sectional view of the main part of the rod-shaped structure light emitting element. In the semiconductor layer 52, the other end of the semiconductor core 51 is larger than the radial thickness T1 of the portion 52b covering the outer peripheral surface of the semiconductor core 51. A thickness T2 in the axial direction of the portion 52a covering the end face on the side is increased.

  Thereby, since the electrode 53 connected to the semiconductor layer 52 side covering the end face of the other end side of the semiconductor core 51 can be connected to the semiconductor layer 52 without overlapping with the semiconductor core 51, the light on the entire side surface of the semiconductor core 51 can be obtained. The take-out efficiency can be improved. Alternatively, even when the electrode 53 connected to the semiconductor layer 52 covering the end surface on the other end side of the semiconductor core 51 overlaps the semiconductor core 51, the amount of overlap can be reduced. The extraction efficiency can be improved. Further, the semiconductor layer 52 has a thickness T2 in the axial direction of the portion 52a covering the end face on the other end side of the semiconductor core 51, rather than the thickness T1 in the radial direction of the portion 52b covering the outer peripheral surface of the semiconductor core 51. The resistance of the portion 52a of the semiconductor layer 52 that covers the end face on the other end side of the semiconductor core 51 becomes high, and the light emission is not concentrated on the other end side of the semiconductor core 51, and the light emission in the side region of the semiconductor core 51 can be strengthened. In addition, the leakage current in the portion 52a of the semiconductor layer 52 that covers the end face on the other end side of the semiconductor core 51 can be suppressed.

  On the other hand, for example, as shown in the schematic cross-sectional view of the main part of the rod-shaped structure light emitting device of the comparative example in FIG. 13, in the semiconductor layer 1052, the radial thickness of the portion 1052 b covering the outer peripheral surface of the semiconductor core 1051. When T11 and the thickness T12 in the axial direction of the portion 1052a covering the other end face of the semiconductor core 1051 are substantially the same, light emission is concentrated on the other end side of the semiconductor core 1051, and the semiconductor core 1051 There is a possibility that light emission in the side surface region of the semiconductor core 1051 may be reduced, or a leak current may be generated in the portion 1052a of the semiconductor layer 1052 that covers the end surface on the other end side of the semiconductor core 1051. In addition, since the electrode 1053 greatly overlaps the semiconductor core 1051, the light extraction efficiency is lowered.

  The rod-shaped structure light emitting device of the fifth embodiment has the same effect as the rod-shaped structure light emitting device of the first embodiment.

[Sixth Embodiment]
FIG. 14 shows a sectional view of a rod-shaped structure light emitting device according to the sixth embodiment of the present invention. As shown in FIG. 2, the rod-shaped structure light emitting device of the sixth embodiment has a semiconductor core 61 made of a rod-shaped n-type GaN having a substantially circular cross section and a p formed so as to cover a part of the semiconductor core 61. A quantum well layer 62 made of type InGaN and a semiconductor layer 63 made of p type GaN formed so as to cover the quantum well layer 62 are provided. The semiconductor core 61 has an exposed portion 61a where the outer peripheral surface on one end side is exposed. Further, the end face on the other end side of the semiconductor core 61 is covered with the quantum well layer 62 and the semiconductor layer 63.

  The quantum well layer 62 is formed such that the axial thickness of the portion 62a covering the end surface on the other end side of the semiconductor core 61 is larger than the radial thickness of the portion 62b covering the outer peripheral surface of the semiconductor core 61. ing.

  FIG. 15 is a schematic cross-sectional view of the main part of the rod-shaped structure light-emitting element. In the quantum well layer 62, the semiconductor core 61 other than the radial thickness T21 of the portion 62b covering the outer peripheral surface of the semiconductor core 61 is shown. The axial thickness T22 of the portion 62a that covers the end face on the end side is increased.

  As a result, the electrode 64 connected to the semiconductor layer 63 side that covers the end face on the other end side of the semiconductor core 61 can be connected to the semiconductor layer 63 without overlapping the semiconductor core 61. The take-out efficiency can be improved. Alternatively, even when the electrode 64 connected to the semiconductor layer 63 side covering the end face on the other end side of the semiconductor core 61 overlaps the semiconductor core 61, the amount of overlap can be reduced, The extraction efficiency can be improved. Further, the quantum well layer 62 has a thickness T22 in the axial direction of the portion 62a covering the end face on the other end side of the semiconductor core 61, rather than a thickness T21 in the radial direction of the portion 62b covering the outer peripheral surface of the semiconductor core 61. Therefore, the concentration of the electric field generated at the corner portion on the other end side of the semiconductor core 61 can be alleviated, the breakdown voltage can be improved, the lifetime of the light emitting element can be improved, and the portion of the quantum well layer 62 covering the end surface on the other end side of the semiconductor core 61 The leakage current at 62a can be suppressed.

  On the other hand, for example, as shown in the schematic cross-sectional view of the main part of the rod-shaped structure light emitting device of the comparative example of FIG. 16, the radial thickness of the portion 1062b covering the outer peripheral surface of the semiconductor core 1061 in the quantum well layer 1062 When the thickness T32 and the thickness T32 in the axial direction of the portion 1052a covering the end face on the other end side of the semiconductor core 1051 are substantially the same, electric field concentration occurs at the corner portion on the other end side of the semiconductor core 61. There is a possibility that the breakdown voltage is lowered, or a leak current is generated in the portion 1062a of the quantum well layer 1062 that covers the end face on the other end side of the semiconductor core 1061. In addition, since the electrode 1064 greatly overlaps with the semiconductor core 1061, the light extraction efficiency is lowered.

  The rod-shaped structure light emitting device of the sixth embodiment has the same effect as the rod-shaped structure light emitting device of the first embodiment.

[Seventh Embodiment]
17A to 17E show process drawings of a method for manufacturing a rod-shaped structure light emitting device according to the seventh embodiment of the present invention. In this embodiment, n-type GaN doped with Si and p-type GaN doped with Mg are used, but the impurity doped into GaN is not limited to this.

  First, as shown in FIG. 17A, an island-shaped catalyst metal layer 75 is formed on a substrate 70 made of n-type GaN (catalyst metal layer forming step). This catalytic metal layer dissolves and takes in compound semiconductor materials such as Ga, N, In, and Al and impurity materials such as Si and Mg, and does not easily form a compound with itself. , Materials such as Au can be used. The island-shaped pattern is formed by forming a catalytic metal layer on the substrate 70 with a thickness of about 100 nm to 300 nm, and then growing the semiconductor core by lithography and dry etching. Open and pattern.

Next, as shown in FIG. 17B, an island-shaped catalyst is formed on the substrate 70 on which the island-shaped catalyst metal layer 75 is formed using a MOCVD (Metal Organic Chemical Vapor Deposition) apparatus. A semiconductor core 71 made of rod-shaped n-type GaN is formed by growing n-type GaN from the interface between the metal layer 75 and the substrate 70 (semiconductor core forming step). The growth temperature is set to about 800 ° C., trimethylgallium (TMG) and ammonia (NH ₃ ) are used as growth gases, silane (SiH ₄ ) is used for supplying n-type impurities, and hydrogen (H ₂ ) is used as a carrier gas. The n-type semiconductor core 71 containing Si as an impurity can be grown. Here, the n-type GaN has hexagonal crystal growth, and a hexagonal columnar semiconductor core is obtained by growing the n-type GaN with the c-axis direction perpendicular to the surface of the substrate 70.

Next, as shown in FIG. 17C, the crystal from the outer peripheral surface of the semiconductor core 71 and the interface between the catalytic metal layer 75 and the semiconductor core 71 with the island-shaped catalytic metal layer 75 held at the tip of the semiconductor core 71. A semiconductor layer 72 made of p-type GaN covering the surface of the semiconductor core 71 is formed by growth (semiconductor layer forming step). In this semiconductor layer formation step, the formation temperature is set to about 900 ° C., trimethylgallium (TMG) and ammonia (NH ₃ ) are used as growth gases, and biscyclopentadienylmagnesium (Cp ₂ Mg) is used for supplying p-type impurities. Can be used to grow p-type GaN having magnesium (Mg) as an impurity.

Next, as shown in FIG. 17D, the outer peripheral surface of the substrate 70 of the semiconductor core 71 is exposed by dry etching (exposure process). At this time, the island-shaped catalytic metal layer 75 is removed and a part of the upper end of the semiconductor core 71 is removed. In the semiconductor layer 72, the thickness in the radial direction of the portion 72b covering the outer peripheral surface of the semiconductor core 71 is removed. In addition, the axial thickness of the portion 72a covering the end face of the other end side of the semiconductor core 71 is increased. In this exposure step, by using SiCl ₄ for dry etching RIE (Reactive Ion Etching), GaN can be easily etched with anisotropy.

  Next, in the separation step, the substrate is immersed in an isopropyl alcohol (IPA) aqueous solution, and the substrate 70 is vibrated along the substrate plane using ultrasonic waves (for example, several tens of kilohertz), thereby standing on the substrate 70. Stress is applied to the semiconductor core 71 covered with the semiconductor layer 72 so that the base near the substrate 70 side of the core 71 is bent, so that the semiconductor core 71 covered with the semiconductor layer 72 is formed as shown in FIG. 17E. The substrate 70 is separated.

  In this way, a fine rod-shaped structure light emitting device separated from the substrate 70 can be manufactured. In the seventh embodiment, the rod-shaped structure light emitting element has a diameter of 1 μm and a length of 10 μm (in FIG. 17A to FIG. 17E, the length of the rod-shaped structure light emitting element is drawn short in order to make the drawings easier to see).

  Furthermore, in the rod-shaped structure light emitting device, the semiconductor layer 72 grows crystal radially outward from the outer peripheral surface of the semiconductor core 71, the radial growth distance is short, and the defects escape outward, so the semiconductor layer 72 with few crystal defects. Thus, the semiconductor core 71 can be covered. Therefore, it is possible to realize a rod-shaped structure light emitting device with good characteristics.

  The rod-shaped structure light emitting element thus cut off from the substrate 70 has one electrode connected to the exposed portion 71a of the semiconductor core 71 and the other electrode connected to the semiconductor layer 72. By flowing current between the electrodes so that recombination of electrons and holes occurs at the pn junction between the semiconductor layer 72 and the inner peripheral surface of the semiconductor layer 72, light is emitted from the pn junction.

  In the semiconductor layer forming step, a p-type semiconductor layer covering the surface of the semiconductor core 71 with the island-shaped catalyst metal layer 75 held at the tip of the semiconductor core 71 without removing the island-shaped catalyst metal layer 75 By forming 72, crystal growth from the interface between the catalytic metal layer 75 and the semiconductor core 71 is promoted more than the outer peripheral surface of the semiconductor core 71, so that the radial direction of the portion 72 b covering the outer peripheral surface of the semiconductor core 71 is increased. The semiconductor layer 72 in which the thickness in the axial direction of the portion 72a that covers the end face on the other end side of the semiconductor core 71 is thicker than the thickness can be easily formed.

  According to the manufacturing method of the rod-shaped structure light emitting element, it is possible to manufacture a fine rod-shaped structure light emitting element having a high degree of freedom in mounting on a device. Here, the fine rod-shaped structure light-emitting element is, for example, a micro-order size having a diameter of 1 μm and a length of 10 μm, or a nano-order size element having a diameter or length of less than 1 μm. In addition, the rod-shaped structure light emitting element can reduce the amount of semiconductor used, can reduce the thickness and weight of the device using the light emitting element, and can emit light from the entire circumference of the semiconductor core covered with the semiconductor layer. Since the emission region is widened by being emitted, a backlight, a lighting device, a display device, and the like with high emission efficiency and power saving can be realized.

  Before the semiconductor layer forming step for forming the semiconductor layer 72, the semiconductor core 71 is held in a state where the island-like catalyst metal layer 75 is held at the tip of the semiconductor core 71 without removing the island-like catalyst metal layer 75. A quantum well layer may be formed so as to cover the surface. Thereby, it is possible to easily form a quantum well layer in which the axial thickness of the portion covering the end face on the other end side of the semiconductor core is thicker than the radial thickness of the portion covering the outer peripheral surface of the semiconductor core.

  The rod-shaped structure light emitting device of the seventh embodiment has the same effect as the rod-shaped structure light emitting device of the fifth embodiment.

  Further, in the semiconductor layer 72, by increasing the thickness in the axial direction of the portion 72a covering the end face on the other end side of the semiconductor core 71 than the thickness in the radial direction of the portion 72b covering the outer peripheral surface of the semiconductor core 71, The electrode connected to the semiconductor layer 72 side covering the end face on the other end side of the semiconductor core 71 may be connected only to the portion 72 a of the semiconductor layer 72 without overlapping to the position of the end face on the other end side of the semiconductor core 71. Therefore, the light extraction efficiency of the entire side surface of the semiconductor core 71 can be improved. Further, since the semiconductor layer 72 has a thickness in the axial direction of the portion 72 a covering the end face on the other end side of the semiconductor core 71 than the thickness in the radial direction of the portion 72 b covering the outer peripheral surface of the semiconductor core 71, The resistance of the portion 72a of the semiconductor layer 72 that covers the end surface on the other end side of the 71 becomes high, the light emission is not concentrated on the other end side of the semiconductor core 71, and the light emission in the side surface region of the semiconductor core 71 can be enhanced. Leakage current in the portion 72a of the semiconductor layer 72 covering the end face on the other end side of the semiconductor core 71 can be suppressed.

[Eighth Embodiment]
18A to 18D show process drawings of the method for manufacturing the rod-shaped structure light emitting device of the eighth embodiment of the present invention. In this embodiment, n-type GaN doped with Si and p-type GaN doped with Mg are used, but the impurity doped into GaN is not limited to this.

  First, as shown in FIG. 18A, a semiconductor film 84 made of n-type GaN is formed on a base substrate 80, and an island-shaped catalyst metal layer 85 is formed on the semiconductor film 84 (catalyst metal layer forming step). . This catalytic metal layer dissolves and takes in compound semiconductor materials such as Ga, N, In, and Al and impurity materials such as Si and Mg, and does not easily form a compound with itself. , Materials such as Au can be used. The island pattern is formed by forming a catalytic metal layer on the semiconductor film 84 to a thickness of about 100 nm to 300 nm, and then growing the semiconductor core by lithography and dry etching. Open and pattern.

Next, as shown in FIG. 18B, the n-shaped catalyst metal layer 85 is formed on the semiconductor film 84 on which the island-shaped catalyst metal layer 85 is formed using an MOCVD apparatus. A semiconductor core 81 made of rod-shaped n-type GaN is formed by crystal growth of the type GaN (semiconductor core forming step). The growth temperature is set to about 800 ° C., trimethylgallium (TMG) and ammonia (NH ₃ ) are used as growth gases, silane (SiH ₄ ) is used for supplying n-type impurities, and hydrogen (H ₂ ) is used as a carrier gas. The n-type GaN semiconductor core 81 with Si as an impurity can be grown. Here, the n-type GaN has hexagonal crystal growth, and a hexagonal columnar semiconductor core is obtained by growing the n-type GaN with the c-axis direction perpendicular to the surface of the semiconductor film 84.

Next, as shown in FIG. 18C, in a state where the island-shaped catalytic metal layer 85 is held at the tip of the semiconductor core 81, crystals from the outer peripheral surface of the semiconductor core 81 and the interface between the catalytic metal layer 85 and the semiconductor core 81 are obtained. A p-type semiconductor layer 82 that covers the surface of the semiconductor core 81 is formed by growth (semiconductor core formation step). In this semiconductor layer formation step, the formation temperature is set to about 900 ° C., trimethylgallium (TMG) and ammonia (NH ₃ ) are used as growth gases, and biscyclopentadienylmagnesium (Cp ₂ Mg) is used for supplying p-type impurities. Can be used to grow p-type GaN having magnesium (Mg) as an impurity.

Next, as shown in FIG. 18D, the surface of the base substrate 80 and the outer peripheral surface of the base substrate 80 of the semiconductor core 81 are exposed by dry etching (exposure process). At this time, the island-shaped catalytic metal layer 85 is removed, and a part of the upper end of the semiconductor core 81 is removed. In the semiconductor layer 82, the thickness in the radial direction of the portion 82b covering the outer peripheral surface of the semiconductor core 81 is reduced. Also, the thickness in the axial direction of the portion 82 a covering the end face of the other end side of the semiconductor core 81 is thick. In this exposure step, by using SiCl ₄ for dry etching RIE, etching can be easily performed with anisotropy in GaN.

  Next, in the separation step, the substrate is immersed in an isopropyl alcohol (IPA) aqueous solution, and the base substrate 80 is vibrated along the plane of the substrate using ultrasonic waves (for example, several tens of kHz) to stand on the base substrate 80. As shown in FIG. 18E, the semiconductor core 81 covered with the semiconductor layer 82 is stressed so that the base of the semiconductor core 81 close to the base substrate 80 side is bent. The core 81 is separated from the base substrate 80.

  In this way, a fine rod-shaped structure light emitting device separated from the base substrate 80 can be manufactured. In the eighth embodiment, the diameter of the rod-shaped structure light-emitting element is 1 μm and the length is 10 μm (in FIGS. 18A to 18E, the length of the rod-shaped structure light-emitting element is drawn short to make the drawings easier to see).

  Furthermore, in the rod-shaped structure light emitting device, the semiconductor layer 82 grows crystal radially outward from the outer peripheral surface of the semiconductor core 81, the growth distance in the radial direction is short, and the defects escape outward, so the semiconductor layer 82 with few crystal defects. Thus, the semiconductor core 81 can be covered. Therefore, it is possible to realize a rod-shaped structure light emitting device with good characteristics.

  The rod-shaped structure light emitting element thus separated from the base substrate 80 has one electrode connected to the exposed portion 81 a of the semiconductor core 81 and the other electrode connected to the semiconductor layer 82, and the outer periphery of the semiconductor core 81. By causing a current to flow between the electrodes so that recombination of electrons and holes occurs at the pn junction between the surface and the inner peripheral surface of the semiconductor layer 82, light is emitted from the pn junction.

  In the semiconductor layer forming step, the p-type semiconductor layer covering the surface of the semiconductor core 81 with the island-shaped catalyst metal layer 85 held at the tip of the semiconductor core 81 without removing the island-shaped catalyst metal layer 85 By forming 82, crystal growth from the interface between the catalytic metal layer 85 and the semiconductor core 81 is promoted more than the outer peripheral surface of the semiconductor core 81, so the radial direction of the portion 82 b covering the outer peripheral surface of the semiconductor core 81 is increased. The semiconductor layer 82 in which the axial thickness of the portion 82a that covers the end face on the other end side of the semiconductor core 81 is thicker than the thickness can be easily formed.

  According to the manufacturing method of the rod-shaped structure light emitting element, it is possible to manufacture a fine rod-shaped structure light emitting element having a high degree of freedom in mounting on a device. Here, the fine rod-shaped structure light-emitting element is, for example, a micro-order size having a diameter of 1 μm and a length of 10 μm, or a nano-order size element having a diameter or length of less than 1 μm. In addition, the rod-shaped structure light emitting element can reduce the amount of semiconductor used, can reduce the thickness and weight of the device using the light emitting element, and can emit light from the entire circumference of the semiconductor core covered with the semiconductor layer. Since the emission region is widened by being emitted, a backlight, a lighting device, a display device, and the like with high emission efficiency and power saving can be realized.

  Further, since the outer peripheral surface of the semiconductor layer 82 and the outer peripheral surface of the exposed portion 81a of the semiconductor core 81 are continuous without a step, the fine rod-shaped light emitting element after separation is placed on the insulating substrate on which the electrodes are formed. When mounting so that the axial direction is parallel to the substrate plane, there is no step between the outer peripheral surface of the semiconductor layer 82 and the outer peripheral surface of the exposed portion 81a of the semiconductor core 81, so the exposed portion 81a of the semiconductor core 81 And the electrode can be reliably and easily connected.

  Before the semiconductor layer forming step of forming the semiconductor layer 82, the semiconductor core 81 is held in a state where the island-shaped catalyst metal layer 85 is held at the tip of the semiconductor core 81 without removing the island-shaped catalyst metal layer 85. A quantum well layer may be formed so as to cover the surface. Thereby, it is possible to easily form a quantum well layer in which the axial thickness of the portion covering the end face on the other end side of the semiconductor core is thicker than the radial thickness of the portion covering the outer peripheral surface of the semiconductor core.

  The rod-shaped structure light emitting device of the eighth embodiment has the same effect as the rod-shaped structure light emitting device of the fifth embodiment.

  Further, in the semiconductor layer 82, the axial thickness of the portion 82a covering the end face on the other end side of the semiconductor core 81 is made larger than the radial thickness of the portion 82b covering the outer peripheral surface of the semiconductor core 81, The electrode connected to the semiconductor layer 82 side covering the end face on the other end side of the semiconductor core 81 may be connected only to the portion 82a of the semiconductor layer 82 without overlapping the position of the end face on the other end side of the semiconductor core 81. Therefore, the light extraction efficiency of the entire side surface of the semiconductor core 81 can be improved. Further, since the semiconductor layer 82 has a thickness in the axial direction of the portion 82a covering the end face on the other end side of the semiconductor core 81, the thickness in the axial direction is larger than the radial thickness of the portion 82b covering the outer peripheral surface of the semiconductor core 81. The resistance of the portion 82a of the semiconductor layer 82 that covers the end face on the other end side of 81 increases, the light emission does not concentrate on the other end side of the semiconductor core 81, and the light emission in the side surface region of the semiconductor core 81 can be enhanced. Leakage current in the portion 82a of the semiconductor layer 82 covering the end face on the other end side of the semiconductor core 81 can be suppressed.

[Ninth Embodiment]
19A to 19E show process drawings of a method for manufacturing a rod-shaped structure light emitting device according to the ninth embodiment of the present invention. In this embodiment, n-type GaN doped with Si and p-type GaN doped with Mg are used, but the impurity doped into GaN is not limited to this.

First, as shown in FIG. 19A, a mask 94 having a growth hole 94a is formed on a substrate 90 made of n-type GaN. For the mask 94, a material that can be selectively etched with respect to the semiconductor core and the semiconductor layer, such as silicon oxide (SiO ₂ ) or silicon nitride (Si ₃ N ₄ ), can be used. The growth hole 94a can be formed by a known lithography method and dry etching method used in a normal semiconductor process. At this time, the diameter of the growing semiconductor core depends on the size of the growth hole 94 a of the mask 94.

  Next, an island-shaped catalyst metal layer 95 is formed on the substrate 90 exposed by the growth hole 94a of the mask 94 (catalyst metal layer forming step). This catalytic metal layer dissolves and takes in compound semiconductor materials such as Ga, N, In, and Al and impurity materials such as Si and Mg, and does not easily form a compound with itself. , Materials such as Au can be used. The island-like catalytic metal layer 95 on the substrate 90 exposed in the growth hole 94a leaves the resist (not shown) used when forming the growth hole 94a by lithography and dry etching on the mask 94. The catalyst metal layer is formed on the resist and the substrate 90 with a thickness of about 100 nm to 300 nm, and the catalyst metal layer on the resist is removed together with the resist by a lift-off method.

Next, as shown in FIG. 19B, the n-type catalyst metal layer 95 is formed on the substrate 90 on which the island-shaped catalyst metal layer 95 is formed from the interface between the island-shaped catalyst metal layer 95 and the substrate 90 using an MOCVD apparatus. A semiconductor core 91 made of rod-shaped n-type GaN is formed by crystal growth of GaN (semiconductor core forming step). The growth temperature is set to about 800 ° C., trimethylgallium (TMG) and ammonia (NH ₃ ) are used as growth gases, silane (SiH ₄ ) is used for supplying n-type impurities, and hydrogen (H ₂ ) is used as a carrier gas. The n-type GaN semiconductor core 91 with Si as an impurity can be grown. Here, the n-type GaN has hexagonal crystal growth, and a hexagonal column-shaped semiconductor core can be obtained by growing the n-type GaN in a c-axis direction perpendicular to the surface of the substrate 90.

Next, as shown in FIG. 19C, with the island-shaped catalytic metal layer 95 held at the tip of the semiconductor core 91, the outer peripheral surface of the semiconductor core 91 and the interface between the catalytic metal layer 95 and the catalytic metal layer 95 are removed. A p-type semiconductor layer 92 covering the surface of the semiconductor core 91 is formed by crystal growth (semiconductor layer forming step). In this semiconductor layer formation step, the formation temperature is set to about 900 ° C., trimethylgallium (TMG) and ammonia (NH ₃ ) are used as growth gases, and biscyclopentadienylmagnesium (Cp ₂ Mg) is used for supplying p-type impurities. Can be used to grow p-type GaN having magnesium (Mg) as an impurity.

  Next, as shown in FIG. 19D, in the exposure process, the region excluding the portion covering the semiconductor core 91 of the semiconductor layer 92 and the mask 94 (shown in FIG. 19C) are removed by etching, and the substrate of the rod-shaped semiconductor core 91 is removed. The exposed portion 91a is formed by exposing the outer peripheral surface on the 90 side. In this state, the island-shaped catalytic metal layer 95 is removed and a part of the upper end of the semiconductor core 91 is removed. In the semiconductor layer 92, the radial thickness of the portion 92b covering the outer peripheral surface of the semiconductor core 91 is removed. In addition, the thickness in the axial direction of the portion 92a that covers the end face on the other end side of the semiconductor core 91 is thicker.

When the mask is made of silicon oxide (SiO ₂ ) or silicon nitride (Si ₃ N ₄ ), a semiconductor core portion that easily covers the semiconductor core and the semiconductor core by using a solution containing hydrofluoric acid (HF) The mask can be etched without affecting the mask, and the semiconductor layer on the mask together with the mask (region excluding the portion of the semiconductor layer covering the semiconductor core) can be removed by lift-off. In the exposure process of this embodiment, the mask can be easily etched without affecting the semiconductor core and the semiconductor layer covering the semiconductor core by dry etching using CF ₄ or XeF _2. The semiconductor layer (region excluding the portion of the semiconductor layer covering the semiconductor core) can be removed.

  Next, in the separation step, the substrate is dipped in an isopropyl alcohol (IPA) aqueous solution, and the substrate 90 is vibrated along the substrate plane using ultrasonic waves (for example, several tens of kHz), whereby the semiconductor standing on the substrate 90 is disposed. Stress is applied to the semiconductor core 91 covered with the semiconductor layer 92 so that the base near the substrate 90 side of the core 91 is bent, and as shown in FIG. 19E, the semiconductor core 91 covered with the semiconductor layer 92 is The substrate 90 is separated.

  In this manner, a fine rod-shaped structure light emitting element separated from the substrate 90 can be manufactured. In the eighth embodiment, the rod-shaped light emitting element has a diameter of 1 μm and a length of 10 μm (in FIG. 19A to FIG. 19E, the length of the rod-shaped structural light emitting element is shortened for easy understanding).

  Furthermore, in the rod-shaped structure light emitting device, the semiconductor layer 92 grows crystal outward from the outer peripheral surface of the semiconductor core 91 in the radial direction, the radial growth distance is short, and the defects escape outward. Therefore, the semiconductor layer 92 with few crystal defects. Thus, the semiconductor core 91 can be covered. Therefore, it is possible to realize a rod-shaped structure light emitting device with good characteristics.

  Thus, the rod-shaped structure light emitting element separated from the substrate 90 has one electrode connected to the exposed portion 91a of the semiconductor core 91, the other electrode connected to the semiconductor layer 92, and the outer peripheral surface of the semiconductor core 91. By flowing current between the electrodes so that recombination of electrons and holes occurs at the pn junction between the semiconductor layer 92 and the inner peripheral surface of the semiconductor layer 92, light is emitted from the pn junction.

  In the semiconductor layer forming step, a p-type semiconductor layer that covers the surface of the semiconductor core 91 in a state where the island-shaped catalyst metal layer 95 is held at the tip of the semiconductor core 91 without removing the island-shaped catalyst metal layer 95. By forming 92, crystal growth from the interface between the catalytic metal layer 95 and the semiconductor core 91 is promoted more than the outer peripheral surface of the semiconductor core 91, so that the radial direction of the portion 92 b covering the outer peripheral surface of the semiconductor core 91 is increased. It is possible to easily form the semiconductor layer 92 in which the thickness in the axial direction of the portion 92a that covers the end face on the other end side of the semiconductor core 91 is thicker than the thickness.

  According to the manufacturing method of the rod-shaped structure light emitting element, it is possible to manufacture a fine rod-shaped structure light emitting element having a high degree of freedom in mounting on a device. Here, the fine rod-shaped structure light-emitting element is, for example, a micro-order size having a diameter of 1 μm and a length of 10 μm, or a nano-order size element having a diameter or length of less than 1 μm. In addition, the rod-shaped structure light emitting element can reduce the amount of semiconductor used, can reduce the thickness and weight of the device using the light emitting element, and can emit light from the entire circumference of the semiconductor core covered with the semiconductor layer. Since the emission region is widened by being emitted, a backlight, a lighting device, a display device, and the like with high emission efficiency and power saving can be realized.

  Before the semiconductor layer forming step for forming the semiconductor layer 92, the island-shaped catalyst metal layer 95 is not removed and the semiconductor core 91 is held with the island-shaped catalyst metal layer 95 held at the tip of the semiconductor core 91. A quantum well layer may be formed so as to cover the surface. Thereby, it is possible to easily form a quantum well layer in which the axial thickness of the portion covering the end face on the other end side of the semiconductor core is thicker than the radial thickness of the portion covering the outer peripheral surface of the semiconductor core.

  The rod-shaped structure light emitting device of the ninth embodiment has the same effect as the rod-shaped structure light emitting device of the fifth embodiment.

  Further, in the semiconductor layer 92, the axial thickness of the portion 92a covering the end surface on the other end side of the semiconductor core 91 is made thicker than the radial thickness of the portion 92b covering the outer peripheral surface of the semiconductor core 91. It is possible to connect the electrode connected to the semiconductor layer 92 side that covers the end face on the other end side of the semiconductor core 91 only to the semiconductor layer 92 without overlapping to the position of the end face on the other end side of the semiconductor core 91. Therefore, the light extraction efficiency of the entire side surface of the semiconductor core 91 can be improved. Further, since the semiconductor layer 92 has a thickness in the axial direction of the portion 92a covering the end face on the other end side of the semiconductor core 91 more than the radial thickness of the portion 92b covering the outer peripheral surface of the semiconductor core 91, the semiconductor core The resistance of the portion 92a of the semiconductor layer 92 that covers the end face on the other end side of the 91 is increased, the light emission is not concentrated on the other end side of the semiconductor core 91, and the light emission in the side surface region of the semiconductor core 91 can be enhanced. Leakage current in the portion 92a of the semiconductor layer 92 covering the end face on the other end side of the semiconductor core 91 can be suppressed.

[Tenth embodiment]
Next, a backlight, an illuminating device, and a display device each including the rod-shaped structure light emitting element according to the tenth embodiment of the present invention will be described. In the tenth embodiment, the rod-shaped structure light emitting elements of the first to ninth embodiments are arranged on an insulating substrate. The arrangement of the rod-shaped structure light-emitting elements is the same as that disclosed in Japanese Patent Application No. 2007-102848 (Japanese Patent Application Laid-Open No. 2008-260073), “Microstructure Arrangement Method, Substrate Arranged with Fine Structure, and Integrated Circuit Device” And display device ".

  FIG. 20 shows a plan view of an insulating substrate used in the backlight, illumination device, and display device of the tenth embodiment. As shown in FIG. 20, metal electrodes 101 and 102 are formed on the surface of the insulating substrate 100. The insulating substrate 100 is an insulator such as glass, ceramic, aluminum oxide, resin, or a substrate in which a silicon oxide film is formed on a semiconductor surface such as silicon and the surface is insulative. When a glass substrate is used, it is desirable to form a base insulating film such as a silicon oxide film or a silicon nitride film on the surface.

  The metal electrodes 101 and 102 are formed in a desired electrode shape using a printing technique. The metal film and the photosensitive film may be uniformly laminated, and a desired electrode pattern may be exposed and etched.

  Although not shown in FIG. 20, pads are formed on the metal electrodes 101 and 102 so that a potential can be applied from the outside. A rod-shaped structure light emitting element is arranged in a portion (array region) where the metal electrodes 101 and 102 face each other. In FIG. 20, 2 × 2 arrangement regions for arranging rod-shaped structure light emitting elements are arranged, but any number may be arranged.

  FIG. 21 is a schematic sectional view taken along line XXI-XXI in FIG.

  First, as shown in FIG. 21, isopropyl alcohol (IPA) 111 including a rod-shaped structure light emitting element 110 is thinly applied on an insulating substrate 100. In addition to IPA 111, ethylene glycol, propylene glycol, methanol, ethanol, acetone, or a mixture thereof may be used. Alternatively, the IPA 111 can use a liquid made of another organic material, water, or the like.

  However, if a large current flows between the metal electrodes 101 and 102 through the liquid, a desired voltage difference cannot be applied between the metal electrodes 101 and 102. In such a case, an insulating film of about 10 nm to 30 nm may be coated on the entire surface of the insulating substrate 100 so as to cover the metal electrodes 101 and 102.

The thickness of applying the IPA 111 including the rod-shaped structure light emitting device 110 is such that the rod-shaped structure light emitting device 110 can move in the liquid so that the rod-shaped structure light emitting device 110 can be arranged in the next step of arranging the rod-shaped structure light emitting device 110. That's it. Therefore, the thickness of applying the IPA 111 is equal to or greater than the thickness of the rod-shaped structure light emitting element 110, and is, for example, several μm to several mm. If the applied thickness is too thin, the rod-like structured light emitting device 110 will not easily move, and if it is too thick, the time for drying the liquid will be longer. Further, the amount of the rod-shaped structure light emitting element 110 is preferably 1 × 10 ⁴ pieces / cm ³ to 1 × 10 ⁷ pieces / cm ³ with respect to the amount of IPA.

  In order to apply the IPA 111 including the rod-shaped structure light emitting element 110, a frame is formed on the outer periphery of the metal electrode on which the rod-shaped structure light emitting element 110 is arranged, and the IPA 111 including the rod-shaped structure light emitting element 110 is formed in the frame with a desired thickness. It may be filled so that However, when the IPA 111 including the rod-shaped structure light emitting element 110 has viscosity, it can be applied to a desired thickness without requiring a frame.

  A liquid made of IPA, ethylene glycol, propylene glycol,..., Or a mixture thereof, or other organic substances, or a liquid such as water is desirable as the viscosity is low for the alignment process of the rod-shaped structure light emitting device 110. It is desirable that it evaporates easily when heated.

  Next, a potential difference is applied between the metal electrodes 101 and 102. In the tenth embodiment, a potential difference of 1V was appropriate. The potential difference between the metal electrodes 101 and 102 can be 0.1 to 10 V. However, if the voltage difference is 0.1 V or less, the arrangement of the rod-shaped structure light emitting elements 110 is poor, and if it is 10 V or more, insulation between the metal electrodes becomes a problem. start. Therefore, it is preferably 1 to 5V, and more preferably about 1V.

  FIG. 22 shows the principle that the rod-shaped structure light emitting device 110 is arranged on the metal electrodes 101 and 102. As shown in FIG. 22, when a potential VL is applied to the metal electrode 101 and a potential VR (VL <VR) is applied to the metal electrode 102, a negative charge is induced in the metal electrode 101 and a positive charge is applied to the metal electrode 102. Is induced. When the rod-shaped structure light emitting device 110 approaches, a positive charge is induced on the side close to the metal electrode 101 and a negative charge is induced on the side close to the metal electrode 52 in the rod-shaped structure light emitting device 110. The charge is induced in the rod-shaped structure light emitting device 110 due to electrostatic induction. In other words, the rod-shaped structured light emitting device 110 placed in an electric field is caused to induce charges on the surface until the internal electric field becomes zero. As a result, an attractive force is generated between each electrode and the rod-shaped structure light emitting element 110 by an electrostatic force, and the rod-shaped structure light emitting element 110 follows the lines of electric force generated between the metal electrodes 101 and 102 and also has each rod-shaped structure light emitting element 110. Since the charges induced in the are substantially equal, the repulsive force caused by the charges causes the charges to be regularly arranged in a fixed direction at almost equal intervals. However, for example, in the rod-shaped structure light-emitting element shown in FIG. 1 of the first embodiment, the direction of the exposed portion 11a side of the semiconductor core 11 covered with the semiconductor layer 12 is not constant, but is random (another embodiment). The same applies to the rod-shaped structure light-emitting element.

  As described above, the rod-shaped structure light emitting device 110 generates charges in the rod-shaped structure light emitting device 110 by the external electric field generated between the metal electrodes 101 and 102, and the rod-shaped structure light emitting device 110 is applied to the metal electrodes 101 and 102 by the attractive force of the charges. Therefore, the size of the rod-shaped structure light emitting element 110 needs to be a size that can move in the liquid. Therefore, the size of the rod-shaped structure light emitting element 110 varies depending on the application amount (thickness) of the liquid. When the amount of liquid applied is small, the rod-like structure light emitting element 110 must have a nano-order size. However, when the amount of liquid applied is large, it may be a micro-order size.

  When the rod-shaped structure light-emitting element 110 is not electrically neutral and is charged positively or negatively, the rod-shaped structure light-emitting element 110 can be formed only by giving a static potential difference (DC) between the metal electrodes 101 and 102. It cannot be arranged stably. For example, when the rod-shaped structure light emitting device 110 is positively charged as a net, the attractive force with the metal electrode 102 in which the positive charge is induced becomes relatively weak. Therefore, the arrangement of the rod-shaped structure light emitting elements 110 is untargeted.

  In such a case, it is preferable to apply an AC voltage between the metal electrodes 101 and 102 as shown in FIG. In FIG. 23, a reference potential is applied to the metal electrode 102, and an AC voltage having an amplitude VPPL / 2 is applied to the metal electrode 101. By doing so, even when the rod-shaped structure light emitting element 110 is charged, the array can be kept as a target. In this case, the frequency of the AC voltage applied to the metal electrode 102 is preferably 10 Hz to 1 MHz, and more preferably 50 Hz to 1 kHz because the arrangement is most stable. Furthermore, the AC voltage applied between the metal electrodes 101 and 102 is not limited to a sine wave, but may be any voltage that varies periodically, such as a rectangular wave, a triangular wave, and a sawtooth wave. VPPL was preferably about 1V.

  Next, after the rod-shaped structure light emitting elements 110 are arranged on the metal electrodes 101 and 102, the insulating substrate 100 is heated to evaporate the liquid and dry the metal. They are arranged at regular intervals along the lines of electric force between 102 and fixed.

  FIG. 24 is a plan view of the insulating substrate 100 on which the rod-shaped structure light emitting elements 110 are arranged. By using the insulating substrate 100 in which the rod-shaped structure light emitting elements 110 are arranged for a backlight of a liquid crystal display device or the like, it is possible to realize a backlight that can be reduced in thickness and weight, has high luminous efficiency, and saves power. it can. Further, by using the insulating substrate 100 in which the rod-shaped structure light emitting elements 110 are arranged as a lighting device, it is possible to realize a lighting device that can be reduced in thickness and weight, has high luminous efficiency, and saves power.

  FIG. 25 is a plan view of a display device using an insulating substrate on which the rod-shaped structure light emitting elements 110 are arranged. As illustrated in FIG. 25, the display device 200 includes a display unit 201, a logic circuit unit 202, a logic circuit unit 203, a logic circuit unit 204, and a logic circuit unit 205 on an insulating substrate 210. In the display unit 201, rod-shaped structure light emitting elements 110 are arranged in pixels arranged in a matrix.

  FIG. 26 shows a circuit diagram of a main part of the display unit 201 of the display device 200. As shown in FIG. 26, the display unit 201 of the display device 200 has a plurality of scanning signal lines GL (see FIG. 26, only one line is shown) and a plurality of data signal lines SL (only one line is shown in FIG. 26), and two adjacent scanning signal lines GL and two adjacent data signal lines SL are provided. Pixels are arranged in a matrix in a portion surrounded by. This pixel has a switching element Q1 having a gate connected to the scanning signal line GL and a source connected to the data signal line SL, a switching element Q2 having a gate connected to the drain of the switching element Q1, and the switching element Q2. And a plurality of light emitting diodes D1 to Dn (bar-shaped structure light emitting element 110) driven by the switching element Q2.

  The pn polarities of the rod-shaped structure light emitting elements 110 are not aligned on one side, but are randomly arranged. For this reason, it is driven by an alternating voltage at the time of driving, and the rod-shaped structure light emitting elements 110 having different polarities emit light alternately.

  In addition, according to the method for manufacturing the display device, the insulating substrate 100 in which the array region having the units of the two electrodes 101 and 102 to which independent potentials are respectively applied is formed, and the insulating substrate 100 is formed on the insulating substrate 100. A liquid including the nano-order size or micro-order size rod-shaped structure light emitting element 110 is applied. Thereafter, independent voltages are applied to the two electrodes 101 and 102, respectively, so that the fine rod-shaped light emitting elements 110 are arranged at positions defined by the two electrodes 101 and 102. Thereby, the rod-shaped structure light emitting element 110 can be easily arranged on the predetermined insulating substrate 100.

  Moreover, in the manufacturing method of the display device, it is possible to manufacture a display device that can reduce the amount of semiconductor to be used and can be reduced in thickness and weight. In addition, since the light emitting region is widened by emitting light from the entire circumference of the semiconductor core covered with the semiconductor layer, the rod-shaped structure light emitting element 110 can realize a display device with high luminous efficiency and power saving. it can.

  In the first to fourth embodiments, the rod-shaped structure light emitting element having the exposed portions 11, 21, 31, 41 where the outer peripheral surface on one end side of the semiconductor cores 11, 21, 31, 41 is exposed has been described. Not limited to this, it may have an exposed portion where the outer peripheral surfaces of both ends of the semiconductor core are exposed, or may have an exposed portion where the outer peripheral surface of the central portion of the semiconductor core is exposed.

  In the first to ninth embodiments, the semiconductor core and the semiconductor layer are made of a semiconductor having GaN as a base material. The present invention may be applied to a light-emitting element using a semiconductor to be used. Further, although the semiconductor core is n-type and the semiconductor layer is p-type, the present invention may be applied to a rod-shaped structure light-emitting element having a reverse conductivity type. Moreover, although the rod-shaped structure light emitting element having a hexagonal columnar semiconductor core has been described, the present invention is not limited to this, and the cross section may be a circular or elliptical rod shape, or the cross section may be other polygonal rod shape such as a triangle. You may apply this invention to the rod-shaped structure light emitting element which has a semiconductor core.

  In the first to ninth embodiments, the diameter of the rod-shaped structure light emitting element is 1 μm and the length is micro order size of 10 μm to 30 μm. However, at least the diameter or length of the nano order is less than 1 μm. A size element may be used. The diameter of the semiconductor core of the rod-shaped structure light emitting element is preferably 500 nm or more and 50 μm or less, and variation in the diameter of the semiconductor core can be suppressed as compared with the rod-shaped structure light emitting element of several tens nm to several hundred nm, and the light emission area, that is, the light emission characteristics. Variation can be reduced and yield can be improved.

  In the first to fourth and seventh to ninth embodiments, the semiconductor core is crystal-grown using the MOCVD apparatus, but the semiconductor is grown using another crystal growth apparatus such as an MBE (molecular beam epitaxial) apparatus. A core may be formed. Further, although the semiconductor core is crystal-grown on the substrate using a mask having a growth hole, the semiconductor core may be crystal-grown from the metal seed by arranging a metal species on the substrate.

  Moreover, in the said 1st-4th, 7th-9th embodiment, although the semiconductor core covered with the semiconductor layer was cut | disconnected from the board | substrate using the ultrasonic wave, it is not restricted to this, A semiconductor core using a cutting tool May be separated from the substrate by mechanical bending. In this case, a plurality of fine rod-shaped light emitting elements provided on the substrate can be separated in a short time by a simple method.

  In the tenth embodiment, a potential difference is applied to the two metal electrodes 101 and 102 formed on the surface of the insulating substrate 100, and the rod-shaped structure light emitting elements 110 are arranged between the metal electrodes 101 and 102. Not limited to this, a third electrode is formed between two electrodes formed on the surface of the insulating substrate, and an independent voltage is applied to each of the three electrodes. You may arrange in the position.

  In the tenth embodiment, the display device including the bar-shaped structure light emitting element has been described. However, the present invention is not limited to this, and the bar-shaped structure light emitting element of the present invention is applied to other devices such as a backlight and a lighting device. Also good.

  Although specific embodiments of the present invention have been described, the present invention is not limited to the first to tenth embodiments, and can be implemented with various modifications within the scope of the present invention.

11, 21, 31, 41, 51, 61, 71, 81, 91 ... Semiconductor core 11a, 21a, 31a, 41a, 51a, 61a, 71a, 81a, 91a ... Exposed portion 12, 23, 32, 43, 52, 63,72,82,92 ... semiconductor layer 22,42,62 ... quantum well layer 13,24,33,44 ... transparent electrode 70,90 ... substrate 75,85,95 ... catalyst metal layer 80 ... underlying substrate 84 ... semiconductor Film 94 ... Mask 100 ... Insulating substrate 101, 102 ... Metal electrode 110 ... Bar light emitting element 200 ... Display device

Claims (10)

A rod-shaped first conductive type semiconductor core;
A semiconductor layer of a second conductivity type formed so as to cover the semiconductor core;
A transparent electrode formed so as to cover the semiconductor layer and not to be electrically connected to the semiconductor core;
The outer peripheral surface of a part of the semiconductor core is exposed ,
The transparent electrode is formed so as not to cover the exposed portion of the outer peripheral surface of the semiconductor core . In the rod-shaped structure light emitting device according to claim 1,
A rod-shaped structure light emitting device, wherein an outer peripheral surface of one end side of the semiconductor core is exposed. The rod-shaped structure light emitting device according to claim 2,
A rod-shaped structure light emitting element, wherein an end face of the other end side of the semiconductor core is covered with the semiconductor layer. In the rod-shaped structure light emitting device according to claim 3,
The rod-like structure light emitting element characterized in that the semiconductor layer has a thickness in the axial direction of a portion covering the end face on the other end side of the semiconductor core, rather than a thickness in a radial direction of a portion covering the outer peripheral surface of the semiconductor core. . In the rod-shaped structure light emitting element according to any one of claims 1 to 4,
A rod-shaped structure light emitting device, wherein a quantum well layer is formed between the semiconductor core and the semiconductor layer. In the rod-shaped structure light emitting device according to claim 1,
While the outer peripheral surface of one end side of the semiconductor core is exposed,
The end face on the other end side of the semiconductor core is covered with the semiconductor layer,
Comprising a quantum well layer formed between the semiconductor core and the semiconductor layer;
The quantum well layer is characterized in that the axial thickness of the portion covering the end face on the other end side of the semiconductor core is thicker than the radial thickness of the portion covering the outer peripheral surface of the semiconductor core. element. In the rod-shaped structure light emitting device according to claim 1,
The semiconductor core is made of an n-type semiconductor,
The rod-shaped structure light emitting element, wherein the semiconductor layer is made of a p-type semiconductor.   A backlight comprising the bar-shaped structure light-emitting element according to claim 1.   An illuminating device comprising the rod-shaped structure light emitting element according to any one of claims 1 to 7.   A display device comprising the bar-shaped structure light emitting element according to claim 1.

Images