JP2003101069A - Group iii nitride quantum dot and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a quantum dot (group III nitride quantum dot) made of a group III nitride semiconductor, and to provide a method for manufacturing the quantum dot. SOLUTION: In dry etching, etching is made while a quartz substrate and a group III nitride semiconductor are placed on the surface of a lower electrode, thus forming a nanopillar structure 50 on the upper surface of the group III nitride semiconductor 101. The gap in the nanopillar structure 50 is filled with a new group III nitride semiconductor to form a filled layer 58, thus manufacturing the group III nitride quantum dot 56.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing group III nitride quantum dots and the like.

[0002]

2. Description of the Related Art In recent years, electronic devices utilizing electrons and excitons confined in semiconductor quantum structures such as quantum wells, quantum wires, and quantum boxes (quantum dots), such as lasers, various nonlinear optical elements, and storage elements, have been reported. Research is ongoing. For example, gallium nitride and other group III nitrides are attracting attention as devices capable of realizing high-quality short wavelength light emitting diodes and laser diodes, Jpn.
J. Appl. Phys. 35, L74 (1996), Appl. Phys. Lett. 6
8, 2105 (1996) reported laser oscillation from an InGaN multilayer quantum well.

There are many problems to be solved before putting an electronic device using such a semiconductor quantum structure into practical use. For example, when considering application to a short wavelength laser diode, the threshold current for laser oscillation of the InGaN multilayer quantum well is reported to be 8.7 kA / cm ^2, and
System III-V laser diode and ZnSe system II-V
100 to 20 which is the threshold current of the group I laser diode
Since it is significantly higher than about 0 A / cm ^2, it is necessary to reduce the threshold current. It is considered that the lasing threshold current can be improved by reducing the size of the active layer structure. That is, when the quantum structure is a one-dimensional quantum wire or a zero-dimensional quantum dot and the size of the active layer structure is about the effective Bohr radius of the exciton, the quantum confinement effect increases the overlap of the electron and hole wavefunctions, resulting in Coulomb interaction. Since it is increased, the binding energy of the exciton is increased, and the oscillator strength of the exciton and the exciton molecule is also increased. And, it is considered that this effect becomes stronger as the dimension of the quantum structure decreases.

Regarding 0-dimensional quantum dots, in InGaAs and InAs / GaAs system which are III-V group semiconductors, it has been reported that quantum dots are spontaneously formed on the lattice mismatched substrate by the Stranski-Krastanov growth mode. (Appl. Phys. Lett. 63,3203 (1993); Nature 36
9, 131 (1994); Appl. Phys. Lett. 65, 1421 (1994)].
In addition, nanoscale GaN dots of various sizes
-It has been reported that it is directly formed on a SiC substrate [V. Dmitriev, K. Irvine, A. Zubrilov, D. Tsvetkov,
V. Nikolaev, M. Jakobson, D. Nelson and A. Sitnikov
a, to be published in "Gallium Nitride and Related
Materials "(Mater. Res. Soc. Symp. Proc.)].

[0005]

In the application of quantum dots to electronic devices, it is necessary to form the quantum dots in a state of being confined in another semiconductor layer. For example, in order to use the GaN quantum dots in an electronic device, it is necessary to form the GaN quantum dots in a state of being confined in, for example, an AlGaN layer having a band gap larger than that of GaN.

However, when GaN is grown on the AlGaN layer by the usual metal organic chemical vapor deposition (MOVPE) or molecular beam epitaxy (MBE), GaN /
Depending on the AlGaN-based energy equilibrium condition and the degree of lattice distortion, GaN grows as a film on the AlGaN layer in a two-dimensionally spread state in the film thickness direction.
GaN quantum dots cannot be formed on the N layer.
This is not limited to the GaN / AlGaN system, but other compound semiconductor systems, such as GaAs / GaAlAs system, Zn, for which application of the semiconductor quantum structure to electronic devices is promising.
The same situation applies to the CdSe / ZnSSe system.

Although it is advantageous to use quantum dots to improve the performance and functionality of electronic devices as described above, it is actually possible to form quantum dots in a semiconductor layer as a device structure. Therefore, there is a situation in which it cannot contribute to high performance of electronic devices.

The present invention has been made in view of such circumstances, and a material system in which a quantum dot cannot be formed by a usual manufacturing method using MOVPE or MBE due to the energy balance condition of the surface and the degree of lattice distortion. And a quantum dot (group III nitride quantum dot) applicable to an electronic device produced by the method, and a good quantum dot. To provide a manufacturable method.

[0009]

MEANS FOR SOLVING THE PROBLEMS, AND ACTION OF THE INVENTION The inventors of the present invention have studied, for example, II gallium nitride compound semiconductors and the like.
Conducting a thorough study on a method for producing a quantum dot using a group I nitride semiconductor, forming a nanometer-order columnar structure (nanopillar) made of a group III nitride semiconductor, and producing a quantum dot using the nanopillar. As a result, they have found that the original purpose can be achieved, and have basically completed the present invention.

According to a first aspect of the present invention, each of the following steps is performed to laminate a group III nitride semiconductor film by laminating at least three layers of a first semiconductor layer, a second semiconductor layer and a third semiconductor layer. A step of producing a nanopillar by dry-etching the group III nitride semiconductor film, and a filling step of growing a new semiconductor in a gap between the nanopillars to grow a filling layer. It is a method for manufacturing a group III nitride quantum dot.

In a second aspect based on the first aspect, in the above-mentioned nanopillar forming step, an etching slow-speed substance having an etching rate smaller than that of the group III nitride semiconductor film is formed on the surface of the group III nitride semiconductor film. With it existing,
The group III nitride semiconductor film is dry-etched. The slow etching material may be placed in the etching chamber as a solid and may be exposed to the etching gas during dry etching. In a third aspect based on the first or second aspect, the bandgap energy of the second semiconductor layer is the bandgap energy of the first semiconductor layer and the bandgap energy of the third semiconductor layer. It is characterized by being smaller than.

A fourth aspect of the invention is the same as the first to third aspects, wherein the laminating step, the nanopillar producing step,
And repeating the filling step to produce a multilayer quantum dot. In a fifth aspect of the invention, the quantum dot distribution density is 10 ⁶ / cm ² to 10 ¹² / cm ^2.
And a group III nitride device. The group III nitride quantum dots having such characteristics can be manufactured by the method according to any one of the first to fourth inventions.

Next, the present invention will be described in more detail. A material constituting a group III nitride quantum dot (having a predetermined number of dots inside a stack of a plurality of group III nitride semiconductors) manufactured by the present invention, that is, a first semiconductor layer to a third layer The semiconductor layers of GaN, GaAlN, In
III group element such as GaN (e.g., gallium) and a group III-V semiconductor containing nitrogen, generally represented by the formula Al _x Ga _y In
It can be represented by _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1 and 0 ≦ x + y ≦ 1). These group III nitride semiconductors may be pure or doped with impurities, and the impurities may be p-type or n-type.

The second semiconductor layer finally becomes quantum dots (sometimes referred to as an active layer or a light emitting layer). In the present specification, the size of the quantum dot has a width of about 1 nm to about 100 nm and a height of about 1 nm to about 100 nm.
Means one. Further, the second semiconductor layer has a sandwich-like structure in which it is sandwiched between the first semiconductor layer and the third semiconductor layer. In order for the group III nitride quantum dots provided with this quantum dot to exhibit good action as a laser,
The bandgap energy of the second semiconductor layer is preferably selected so that it is a substance smaller than the bandgap energy of the first semiconductor layer and the bandgap energy of the third semiconductor layer. In addition, the plurality of layers forming the group III nitride quantum dots includes a case where at least one layer among all layers is formed of a group III nitride semiconductor. Further, the group III nitride semiconductor may be formed on a substrate such as sapphire. INDUSTRIAL APPLICABILITY The present invention can be favorably used for manufacturing a group III nitride quantum dot having a multilayer structure such as a double hetero structure.

Examples of the dry etching method that can be used in the “nanopillar manufacturing process” include a method of performing dry etching in the presence of an etching slow substance having an etching rate smaller than that of a group III nitride semiconductor, and electron beam exposure. There is a method of performing dry etching using an appropriate etching gas and tray without forming a mask using a lithography technique such as, but the technical scope of the present invention is not limited to these methods, and the nanopillar Any method capable of producing "Slow etching material" means that when dry etching,
It is a substance having an etching rate smaller than that of the group III nitride semiconductor which is an essential target substance. Such slow etching material II
If present on the surface of the group I nitride semiconductor, the dry etching speed will not be uniform on the target surface. For this reason, in the portion where the slow etching material is present, the etching is performed later than in the portion where it is not, so that irregularities (nanopillars) are formed on the target surface (details will be described later). As a concrete slow etching material, quartz (Si
O ₂ ), sapphire, nickel, organic resist and the like are exemplified.

"Dry etching" is an etching method utilizing discharge of gas, unlike chemical wet etching, and is, for example, reactive ion etching (RIE) or electron cyclotron resonance etching (EC).
R), electromagnetic coupling plasma etching (ICP) and the like. The "present state" means a state in which the slow etching substance is present on the surface of the group III nitride semiconductor film in the order of nanometer (range smaller than 1 μm). As a method of achieving such a state, for example, (i) by performing a dry etching in a chamber in which the etching slow substance is placed as a solid, the etching slow substance is deposited in the etching chamber by a sputtering effect. A method of generating and adhering it to the surface of the group III nitride semiconductor film, (ii) a method of flowing an etching slowing substance into the etching chamber, (iii) an etching slowing substance of the order of nanometers in advance of the group III nitride semiconductor film Examples include a method of sprinkling the surface appropriately.

The term "nanopillar" means a structure in which a plurality of small columns having a cross section having a size on the order of nanometers are projected. The "tray" is preferably made of, for example, quartz (SiO ₂ ) or sapphire. In the first invention, at least three layers of the first semiconductor layer, the second semiconductor layer, and the third semiconductor layer are laminated to form a group III nitride semiconductor film (laminating step). Next, the group III nitride semiconductor film is dry-etched to produce nanopillars (nanopillar fabrication step). Finally, a group III nitride quantum dot can be manufactured by growing a new semiconductor in the gap between the nanopillars to grow a filling layer (filling step).

The material constituting the "filling layer" is the first
It is also possible to select and use any one of the materials forming the semiconductor layer or the third semiconductor layer, but it is preferable to use a group III different from any of the first semiconductor layer to the third semiconductor layer. Select a nitride semiconductor. Note that as the filling layer, it is preferable to select a semiconductor whose conductivity is lower than that of the material forming the second semiconductor layer. This is because it becomes possible to selectively apply a voltage to the quantum dots provided at the predetermined positions.

More specifically, a buffer layer such as AlN is formed on a substrate such as sapphire (for example, M
It can be produced by the OVPE method. ) On the buffer layer by, for example, the MOVPE method, the first semiconductor layer and the second semiconductor layer.
The semiconductor layer and the third semiconductor layer are sequentially laminated to form a group III nitride semiconductor film (lamination step).

Then, by dry etching, III
A nanopillar is produced by etching the metal nitride semiconductor film. For example, a group III nitride semiconductor film is placed on one upper surface of a pair of positive and negative electrodes (for example, parallel plate electrodes) installed in an etching chamber whose pressure is reduced to the order of 10 ⁻⁴ Pa, and quartz (SiO ₂ ) Or
Using sapphire as a tray for the negative electrode, high-frequency power is applied to the electrode to generate plasma from the plasma generating gas, and the group III nitride semiconductor film is etched by the plasma to form nanopillars. Most of the manufactured nanopillars have a size of about 100 nm or less, and the distance between adjacent nanopillars (gap) can be about several tens nm to about 100 nm on average. Therefore, the nanopillars and the gaps can be repeatedly formed at a distance of about 100 nm. Then, about 1 × 10 ⁶ nanopillars are formed in 1 cm, and about 1 × 10 ⁶ in 1 cm ^2.
Approximately ¹² quantum dots can be constructed.

A new group III nitride semiconductor is grown in the space between the nanopillars made of the group III nitride semiconductor thus formed (filling step). At this time, it is preferable to perform chemical etching, for example, so that the slow etching material on the surface of the nanopillar can be completely removed to contribute to the smooth formation of the filling layer. As a method of filling,
For example, an organic metal compound vapor deposition method (MOVPE (meta
l organic vaper phaseepitaxy)), hydride VP
E method (hydride vapor phase epitaxy (HVPE)) or molecular beam epitaxial growth method (MBE (molecular
beam epitaxy)) and the like.

Further, the stacking process, the nanopillar manufacturing process, and the filling process are set as one set, and the processes of to are sequentially repeated to manufacture quantum dots formed in multiple layers in the height direction. In such a multi-layered quantum dot, the side faces are almost vertical and the heights are uniform, so mutual quantum dots excite each other,
Highly efficient light emission is possible. According to the present invention, a fine needle-like structure (nanopillar) can be easily formed, and a quantum dot can be manufactured by filling a gap between the nanopillars with a new group III nitride semiconductor. At this time, the dot density is 10 ⁶ dots / cm ² ~
It is possible to provide 10 ¹² / cm ² group III nitride quantum dots.

[0023]

According to the present invention, the nanopillars can be easily formed on the surface of the group III nitride semiconductor film, and the gap between the nanopillars can be efficiently filled with a new group III nitride semiconductor. Group III nitride quantum dots can be manufactured. Further, it becomes possible to manufacture a light emitting diode display having a large area and a large area fluorescent display using a field emission cold cathode by using the group III nitride quantum dots as described above.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments or examples, and can be implemented in various modes without changing the gist of the invention. Furthermore, the technical scope of the present invention extends to an equivalent range. FIG. 1 is a schematic diagram showing an example of a dry etching apparatus that can be used to carry out the present invention. This apparatus includes an etching chamber 1, a high frequency power supply 2, an exhaust device and a plasma generating gas introducing device.

More specifically, a pair of positive and negative parallel plate electrodes 1 are provided inside the etching chamber 1 made of, for example, stainless steel.
1, 12 are installed facing each other. In both electrodes, the anode 11 is generally kept at the ground potential, while the cathode 12 is applied with high frequency power. The cathode 12 is strongly hit by the plasma gas, and its temperature rises. Therefore, in order to cool the cathode 12, it has a hollow structure so that cooling water can flow to the back surface side. 13.56 for the cathode 12
A high frequency power supply 2 of MHz is connected through a matching box 22 to control plasma. An exhaust pipe 3 is provided in the etching chamber 1. In the exhaust pipe 3,
An exhaust device (not shown) in which a dry pump, a turbo pump and the like are combined is connected. By driving this exhaust device, the internal space of the etching chamber 1 is, for example, 10 ⁻⁴ Pa.
The following vacuum can be applied. The pressure in the etching chamber 1 is adjusted by, for example, a pressure adjusting valve 33 disposed in the middle of the exhaust pipe 3, and is always maintained at a certain degree of vacuum.

The etching chamber 1 is further provided with gas introduction pipes 4a, 4b for introducing each plasma generating gas into the etching chamber 1. These gas introduction pipes 4
The other ends of a and 4b are connected to an external plasma generating gas source (not shown). More specifically, the etching chamber 1 is provided with a first gas introduction pipe 4a for introducing an etching gas (for example, chlorine gas) and other gas (mixed with the first gas when necessary). And a second gas introduction pipe 4b for introducing a gas for performing dry etching). The flow rate of each gas is controlled by mass flow controllers 44a and 44b provided in the gas introduction pipes 4a and 4b, respectively. When only the first gas is introduced into the etching chamber 1 as the plasma generating gas, the gas introducing pipe 44b is omitted or closed.

Next, the operation of forming a nanopillar by etching the group III nitride semiconductor film using the above dry etching apparatus will be described. In the example below,
Although n-GaN, InGaN, and p-GaN have been exemplified as the semiconductors forming the first to third semiconductor layers, respectively, the technical scope of the present invention is not limited to this, and the formula A
_{l x Ga y In 1-xy} N (0 ≦ x ≦ 1,0 ≦ y ≦ 1 and, 0 ≦ x + y
A nitride semiconductor represented by ≦ 1) can be used. In that case, it is preferable to select a combination in which the bandgap energy of the second semiconductor layer is smaller than the bandgap energy of the first and third semiconductor layers.

First, the structure of the group III nitride semiconductor film will be described with reference to FIG. 2 as an example. As shown in FIG. 2A, this group III nitride semiconductor film is provided on the upper surface side of the buffer layer 52 provided on the upper surface of the sapphire substrate 51, for example. The buffer layer 52 (for example, about 20n
AlN having a thickness of about m can be used. ) On the upper surface of the first semiconductor layer 53 (for example, n-GaN can be used) and the second semiconductor layer 54 (for example, InGaN) in order from the lower layer by MOVPE method.
Can be used. ), And the third semiconductor layer 55.
(For example, non-doped GaN or InGaN, p-type GaN or InGaN, or AlInGaN can be used.) At least three layers of the group III nitride semiconductor film 60 are formed (FIG. 2B). .

Here, the thickness of the first semiconductor layer 53 is about several hundred to several thousand nm, and the thickness of the second semiconductor layer 54 (finally forming quantum dots to form a light emitting layer) is about. Several nm to about 60 nm, and the thickness of the third semiconductor layer 55 is about several nm to 100 n.
It is preferably about m. In addition, the second semiconductor layer 5
4 has a band energy gap of the first semiconductor layer 53.
It is preferable to select a material having a band energy gap smaller than that of the third semiconductor layer 55. Further, the second semiconductor layer 54 and the third semiconductor layer 55 can be stacked.

To etch the sample 101 (showing the entire structure including the group III nitride semiconductor film 60 and the substrate 51) provided with the group III nitride semiconductor film 60, the upper surface of each cathode 12 is etched. On the side, the quartz substrate 10 as a solid
2 is placed, and the sample 101 in the form of, for example, a wafer is placed on the upper surface or the periphery thereof. Sample 1
When 01 is placed on the upper surface of the quartz substrate 102, the quartz substrate 102 has a larger cross-sectional shape than the sample 101, and the quartz substrate 102 is exposed to the etching gas.

Then, the exhaust device is driven to exhaust the inside of the etching chamber 1 to a pressure of the order of 10 ^-4 Pa. After the degree of vacuum inside the etching chamber 1 is stabilized, chlorine gas is introduced into the internal space of the etching chamber 1 from the gas introduction pipe 4a while being controlled by the mass flow controller 44a so as to have a predetermined flow rate. At the same time, the inside of the etching chamber 1 is exhausted by the exhaust device and the pressure adjusting valve 33 is adjusted to control the internal pressure of the etching chamber 1 to a predetermined pressure. When a voltage is applied from the high frequency power source 2 through the matching box 22 after the internal pressure of the etching chamber 1 is stabilized, chlorine gas plasma is generated between the electrodes 11 and 12.

This chlorine gas plasma is used for the quartz substrate 102.
While etching, the group III nitride semiconductor film 60 of the sample 101 is sputtered and etched (nanopillar fabrication step). Thus, by the etching operation, II
Nanopillars 50 are formed on the surface of the group I nitride semiconductor film 60, as shown in FIG. The diameter of the nanopillar 50 is about 10 nm to about 200 nm. Also,
The distance between adjacent nanopillars 50 is about 10 on average.
It becomes about 0 nm. The diameter and spacing of the nanopillars 50 can be appropriately changed depending on the etching conditions.

Next, as shown in FIG. 3D, a new group III nitride semiconductor is filled in the gap of the nanopillar 50 to form a filling layer 58 (filling step). Examples of the filling method include the MOVPE method, the HVPE method, the MBE method, and the like as described above. In addition, the nano pillar 50
When it is not necessary to provide it on the entire surface of the group III nitride semiconductor film 60, as shown in FIG. 4, a mask 57 (for example, a mask made of SiO ₂ ) is applied to a place which does not need to be etched in advance, By performing dry etching, the nanopillars 50 can be formed only at desired positions.

In this way, the quantum dots (Group III nitride quantum dots) 56 made of Group III nitride semiconductor can be manufactured. In addition, as shown in FIG.
A light emitting device can be manufactured by providing a pair of positive and negative electrodes 61 and 62 above and below. In that case, it is preferable that a semiconductor layer 59 (for example, p-GaN can be used) is further stacked on the upper surface side of the filling layer 58, and the electrode 61 is provided on the upper surface of the semiconductor layer 59. In addition, from the state shown in FIG.
Group III nitride semiconductor (for example, n-
GaN, InGaN, and p-GaN) are stacked III
By forming a group nitride semiconductor film and repeating the nanopillar fabrication process and the filling process for the semiconductor film in the same manner as described above, the multilayer quantum dot 70 can be easily manufactured as shown in FIG. 7. it can.

[0035]

EXAMPLES The present invention will now be described with reference to examples. The above-described etching apparatus (FIG. 1) was used in each of the following examples. Example 1 On a sapphire <0001> substrate, via a buffer layer 52, n-GaN 53 (corresponding to the first semiconductor layer in the present invention) and InGaN by, for example, MOVPE method.
54 (corresponding to the second semiconductor layer in the present invention),
And a sample having a group III nitride semiconductor film 60 on which p-GaN 55 (which is harmful to the third semiconductor layer in the present invention) was grown was used as a sample 101 for etching.

Here, n-GaN 53 and p-GaN 5
5 has a thickness of about 300 nm, and InGaN 54 has a thickness of about 2 nm.
It was set to 0 nm. SiO ₂ is deposited on the upper surface of the sample 101 to a thickness of about 300 nm by, for example, an RF sputtering method, and is deposited by a general photolithography technique.
A line and space pattern having a size of 5 μm in the 1100> direction was formed, and used as an etching sample 101. The quartz substrate 102 was placed on the stage of the etching chamber 1. The etching sample 101 was placed on the periphery or the upper surface of the quartz substrate 102.

After that, the etching chamber 1 is moved to 5 by a vacuum pump.
It was evacuated to × 10 ^-4 Pa. After the degree of vacuum inside the etching chamber 1 becomes stable, the gas introducing pipe 4 is introduced into the inside of the etching chamber 1.
Chlorine gas was introduced from a at a flow rate of 30 ml / min while being controlled by the mass flow controller 44a. At the same time, the inside of the etching chamber 1 is evacuated by the vacuum pump, the pressure adjusting valve 33 is adjusted, and the etching chamber 1
The inside was controlled to a reduced pressure of 6 Pa. After confirming that the degree of vacuum in the etching chamber 1 is stable, a voltage is applied by the high frequency power source 2 to generate plasma between the electrodes 11 and 12, and the plasma is generated under the condition of 100 W (the area is 177 cm ² ). Dry etching was performed for 4 minutes.

After dry etching, the sample 101 was taken out of the etching chamber 1 and the etched surface was observed with a scanning electron microscope (SEM). FIG. 5 is a view showing a photograph of the structure of the etching surface of the group III nitride semiconductor film observed by SEM. The manufacturing process of the nanopillar according to the present embodiment can be considered as follows, for example. That is, chlorine ions in the plasma collide with the quartz substrate around GaN, and SiO _{2 is} generated by the sputtering effect.
Jumps into the plasma. It is considered that a part of the SiO ₂ is ionized and redeposits on the GaN film which is negatively biased. Here, since SiO ₂ has a low etching rate for chlorine gas plasma of about 1/10 to 1/20 as compared with GaN, it functions as a minute mask, so that a minute uneven structure is formed on the surface of the sample 101. Is formed.

Since the electric field is higher at a portion where SiO ₂ is attached and which is slightly convex than the concave portion, S
It is considered that the probability that iO ₂ will adhere increases. It is considered that the nanopillar structure was obtained as a result of re-deposition of SiO ₂ and etching by chlorine gas plasma being repeated in parallel in this way. However, XPS
As a result of the analysis, Si was detected on sapphire,
No Si was detected on GaN. For this reason, at present, the manufacturing process of the nanopillar is not always clear in the method of this embodiment.

The thickness of the nanopillar structure was about several tens nm to 100 nm, and the height thereof was about 500 nanometers. The density of nanopillars is about
It was on the order of 10 ⁶ -10 ¹² / cm ² . It was found that the height of the nanopillar greatly depends on the etching time.

A new group III nitride semiconductor (GaN) could be filled in the gaps of the nanopillar structure thus manufactured by, for example, the MOVPE method to form the filling layer 58 (see FIG. 3D). ). At that time, the conditions are trimethylgallium (TMG) 48 μmol / min,
NH ₃ was flown at 1 l / min, and the temperature was set to 1000 ° C. and 300 Torr. In addition, from the state shown in FIG. 3D, n-GaN, InGaN, and p-GaN are newly stacked on the upper surface side, and the stacked semiconductor film is formed into nanopillars by a dry etching operation, and By repeating the operation of filling the gaps of the nanopillars, the multilayer quantum dot 70 shown in FIG. 7 can be manufactured.

As described above, according to this embodiment, the nanopillars 56 can be easily formed on the surface of the group III nitride semiconductor film 60, and the gaps between the nanopillars 56 are newly formed.
By filling with the group I nitride semiconductor, the group III nitride quantum dots 56 can be efficiently manufactured. Also,
By using such a group III nitride quantum dot 56, it becomes possible to manufacture a light emitting diode display having a large area and a large area fluorescent display using a field emission cold cathode. Also, in particular, the stacking step, the nanopillar manufacturing step, and the filling step are set as one set, and
By sequentially repeating the above process, when a multi-layered quantum dot is formed in a multi-layered structure in the height direction, the quantum dots are excited because they are quantum dots whose sides are almost vertical and whose heights are even. As a result, highly efficient light emission is possible.

[Brief description of drawings]

FIG. 1 is a sectional view showing an outline of an etching apparatus that can be used for implementing the present invention.

FIG. 2 is a diagram showing a process for producing a group III nitride quantum dot. (A) A sectional view of a substrate before laminating a group III nitride semiconductor (b) A sectional view after laminating a group III nitride semiconductor

FIG. 3 is a diagram showing a process for producing a group III nitride quantum dot (c) A cross-sectional view when a nanopillar is formed by dry etching (d) A gap between the nanopillars is filled with a new group III nitride semiconductor Cross section

FIG. 4 is a cross-sectional view when a nanopillar is formed by applying a mask at a predetermined place.

5 is a view showing an electron micrograph showing a structure of an etching surface after etching the group III nitride semiconductor film according to Example 1. FIG.

FIG. 6 is a cross-sectional view of a group III nitride quantum dot provided with a pair of positive and negative electrodes.

FIG. 7 is a cross-sectional view of a multilayer quantum dot after the process of manufacturing a quantum dot has been repeated multiple times.

[Explanation of symbols]

50 ... Nanopillar 51 ... Sapphire 52 ... Buffer layer 53 ... n-GaN (first semiconductor layer) 54 ... InGaN (second semiconductor layer, light emitting layer) 55 ... p-InGaN (third semiconductor layer) 56 ... Quantum dot 58 ... GaN (filling layer) 59 ... p-GaN (semiconductor layer) 60 ... Group III nitride semiconductor film 61, 62 ... Electrodes 70 ... Multilayer quantum dots 101 ... Group III nitride semiconductor 102 ... Quartz substrate

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Claims (5)

[Claims] 1. The following steps, a first semiconductor layer and a second
Laminating step of laminating at least three layers of the semiconductor layer and the third semiconductor layer to produce a group III nitride semiconductor film, and nanopillar fabrication for producing nanopillars by dry etching the group III nitride semiconductor film And a filling step of growing a new semiconductor in the gaps between the nanopillars to grow a filling layer. 2. The group III nitriding step is carried out in the step of forming the nanopillar, wherein a slow etching substance having an etching rate smaller than that of the group III nitride semiconductor film is present on the surface of the group III nitride semiconductor film. 3. The III according to claim 1, wherein the object semiconductor film is dry-etched.
Method for producing group nitride nitride quantum dots. 3. The band gap energy of the second semiconductor layer is smaller than the band gap energy of the first semiconductor layer and the band gap energy of the third semiconductor layer. The method for producing a group III nitride quantum dot according to claim 2. 4. The group III nitride according to claim 1, wherein a multilayer quantum dot is manufactured by repeating the stacking step, the nanopillar manufacturing step, and the filling step. Method for manufacturing quantum dots. 5. The distribution density of quantum dots is 10 ⁶ pieces / cm ^2.
A group III nitride device characterized by having a density of 10 ¹² / cm ² .