WO2003028118A1

WO2003028118A1 - Iii group nitride quantum dot and production method therefor

Info

Publication number: WO2003028118A1
Application number: PCT/JP2002/009786
Authority: WO
Inventors: Kazumasa Hiramatsu; Hideto Miyake; Harumasa Yoshida
Original assignee: Nagoya Industrial Science Research Institute
Priority date: 2001-09-25
Filing date: 2002-09-24
Publication date: 2003-04-03
Also published as: JP2003101069A

Abstract

A quantum dot (III group nitride dot) consisting of a III group nitride semiconductor, and a method of satisfactorily producing such a quantum dot. As shown in Fig. 3, etching is conducted during a dry etching with a quartz substrate and a III group nitride semiconductor placed on the upper surface of an electrode below to thereby form a nano-pillar structure (50) on the top surface of a III group nitride semiconductor (101). The gaps in this nano-pillar structure (50) are filled with a new III group nitride semiconductor to form a filling layer (58), thereby producing a III group nitride quantum dot (56).

Description

Specification

Group III nitride quantum dots and method for producing the same

The present invention relates to a method for producing a group III nitride quantum dot and the like. Background art

In recent years, research has been conducted on electronic devices using 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. ing. For example, gallium nitride and other group III nitrides have been 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. 68, 2105 (1996) reports laser oscillations from InGaN multilayer quantum wells.

There are many problems that need to be solved in putting electronic devices using such semiconductor quantum structures into practical use. For example, when considering the application to short-wavelength laser diode, wherein I n G a N multilayer threshold current of the laser oscillation of the quantum wells 8. 7 kA / cm ² is reported to, G a A s based III one since significantly higher as compared with 1 0 0~2 0 0 a / cm 2 about a group V laser die O over de Ya Z n S e system II one group VI laser die O over de threshold current, lowering the threshold current It is necessary. It is thought that the threshold current of laser oscillation can be improved by reducing the size of the active layer structure. In other words, if 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 electron and hole wave functions overlap due to the quantum confinement effect and Coulomb interaction. Is increased, the binding energy of the exciton increases, and the oscillator strength of the exciton and the exciton molecule also increases. And this effect is thought to be stronger as the dimension of the quantum structure decreases.

Regarding the zero-dimensional quantum dot, the 111-V group semiconductors InGaAs and InGasZGaAs systems use the Stranski-Krastanov growth mode on a lattice-mismatched substrate. It is reported that quantum dots are formed spontaneously [Appl. Phys. Lett. 63, 3203 (1993); Nature 369, 131 (1994); Appl. Phys. Lett. 65, 1421 (1994)]. . It has also been reported that nanoscale GaN dots of various sizes are formed directly on 6H-SiC substrates [V. Dmitriev, K. Irvine, A. Zubrilov, D. Tsvetkov, V. Nikolaev, M. Jakobson, D. Nelson and A. Sitnikova, to be published in "Gallium Nitride and Related Materials" (Mater. Res. Soc. Symp. Proc.)].

When applying quantum dots to electronic devices, it is necessary to form the quantum dots in a state where they are confined in another semiconductor layer. For example, in order to use GaN quantum dots for electronic devices, it is necessary to form GaN quantum dots in a state where they are confined within, for example, an A1 GaN layer with a larger band gap than GaN. is there.

However, when GaN is grown on the A 1 GaN layer by ordinary metal-organic chemical vapor deposition (MOVP E) or molecular beam epitaxy (MBE), GaN / A 1 GaN Depending on the energy balance conditions of the system and the degree of lattice distortion, GaN grows in a film direction in a two-dimensionally spread state on the A 1 GaN layer as a film on the A 1 GaN layer. GaN quantum dots cannot be formed at the same time. This is not limited to the G a N / A 1 G a N system, but also for other compound semiconductor systems for which the application of semiconductor quantum structures to electronic devices is promising, such as G a A s / G a A 1 A s The same situation exists in the system, ZnCdSe / ZnSSe system.

Thus, although it is advantageous to use quantum dots for higher performance and higher functionality of electronic devices, in reality, quantum dots cannot be formed in a semiconductor layer as a device structure, However, there were circumstances in which it was not possible to contribute to higher performance of electronic devices.

The present invention has been made in view of such a situation, and is based on a material system that cannot form a quantum dot due to the surface energy balance condition and the degree of lattice distortion in a normal production method using MOVPE-MBE. To provide a method capable of forming quantum dots, and to provide a quantum dot (group III nitride quantum dot) applicable to an electronic device manufactured by the method, and to provide such a quantum dot. It is to provide a method which can be manufactured easily. Disclosure of the invention

The present inventors have intensively studied a method of manufacturing a quantum dot using a group II nitride semiconductor such as a gallium nitride-based compound semiconductor, and have found a nanometer-order columnar structure (a nanopillar) made of a group II nitride semiconductor. ), And found that the initial objective can be achieved by manufacturing quantum dots using the nanopillars, and basically completed the present invention.

The first invention includes the following steps: (1) a lamination method in which at least three layers of a first semiconductor layer, a second semiconductor layer, and a third semiconductor layer are laminated to form a group III nitride semiconductor film; (2) a nanopillar manufacturing step of manufacturing a nano-pillar by dry-etching the group III nitride semiconductor film, and (3) a filling step of growing a new semiconductor in a gap between the nano-pillars and growing a filling layer. This is a method for producing an in-group nitride quantum dot.

According to a second aspect, in the first aspect, in the nanopillar manufacturing step (1), an etching slow substance having an etching rate smaller than that of the group II nitride semiconductor film is present on the surface of the group II nitride semiconductor film. In this state, the III nitride semiconductor film is dry-etched. Note that the etching slow-moving substance is placed as a solid in the etching chamber, and may be exposed to an etching gas at the time of dry etching.

In a third aspect based on the first or second aspect, the band gap energy of the second semiconductor layer is the band gap energy of the first semiconductor layer and the band gap energy of the third semiconductor layer. It is characterized by being smaller than

The fourth invention is characterized in that, in the first invention to the third invention, a multilayer quantum dot is produced by repeating the above-mentioned (1) laminating step, (2) the above-mentioned nobular manufacturing step, and (3) the filling step. .

A fifth invention is a group III nitride device, characterized in that the quantum dots have a distribution density of 10 ⁶ / c πι ² to 10 ¹² Z cm ² . The group III nitride quantum dot 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.

The material constituting the group III nitride quantum dots (having a plurality of group III nitride semiconductors and having a predetermined number of dots inside) manufactured by the present invention, ie, the first semiconductor layer to the third Is a group III-V semiconductor containing nitrogen and a group III element (for example, gallium) such as GaN, GaAlN, and InGAN. _X G a _y I ri — _y N (0≤x≤l, 0≤y ^ l, and O ^ x + y ^ l). These group III nitride semiconductors may be pure or doped with impurities, and the impurities may be either p-type or n-type.

The second semiconductor layer eventually becomes a quantum dot (sometimes referred to as an active layer or a light emitting layer). In this specification, the size of the quantum dot is about 1 ηπ!約 100 nm, height of about 1 nm to about 100 nm.

In addition, the second semiconductor layer has a sandwich-like structure sandwiched between the first semiconductor layer and the third semiconductor layer. In order for the group II nitride quantum dot provided with this quantum dot to exhibit a good function as a laser, the band gap energy of the second semiconductor layer is determined by the band gap energy of the first semiconductor layer and the third band gap energy. It is preferable to make a selection so that the material becomes smaller than the band gap energy of the semiconductor layer. Further, the second semiconductor layer is not limited to a single semiconductor layer, and includes a multi-quantum structure in which the semiconductor layers having different heights of the hand gap energy from about 1 nm to about 100 nm are stacked. In this case, for example, it can be favorably used for the production of a group III nitride quantum dot having a multilayer structure such as a double hetero structure. In such a multi-layer quantum dot, the quantum dots are almost perpendicular and the height is uniform, so that the quantum dots excite each other, enabling highly efficient light emission.

Further, the plurality of layers constituting the group III nitride quantum dots include a case where at least one of all the layers is formed of a group III nitride semiconductor. Further, the group III nitride semiconductor may be formed on a substrate such as sapphire.

Examples of dry etching methods that can be used in the “nanopillar fabrication process” include: 1) dry etching in the presence of an etching slow substance having a lower etching rate than group III nitride semiconductors, and 2) electron beam exposure. Without forming a mask using lithography technology such as And a method of performing dry etching using a tray. However, the technical scope of the present invention is not limited to these methods, and may be any method that can produce nanopillars.

“Etching slow material” refers to a material that has a lower etching rate than the intrinsic target material of a group III nitride semiconductor when dry-etched. If such an etching slow substance is present on the surface of the group III nitride semiconductor, the dry etching speed will not be uniform on the target surface. For this reason, the portion where the etching slow substance is present will be etched more slowly than the portion where it is not, and irregularities (nanopillars) will be formed on the target surface (details will be described later). Specific examples of the etching slow substance include quartz (Sio ₂ ), sapphire, nickel, and an organic resist.

“Dry etching” is an etching method that uses gas discharge, unlike chemical wet etching. For example, reactive ion etching (RIE), electron cyclotron resonance etching (ECR), and electromagnetically coupled plasma There are methods such as etching (ICP).

“Present state” means a state in which an etching slow substance is present on the surface of the group III nitride semiconductor film in the order of nanometer (range smaller than 1 / im). As a method for achieving such a state, for example, (i) etching is performed while a solid etching slow substance is placed in a chamber where dry etching is performed, so that the etching slow substance is etched by a sputtering effect. A method of depositing it on the surface of a group III nitride semiconductor film, (ii) a method of flowing an etching slow material into an etching chamber, and (iii) a method of previously depositing a nanometer-order etching slow material in a group III nitride. There is a method of appropriately sprinkling it on the surface of the semiconductor film.

“Nanopillar” means a structure in which multiple small pillars with a cross section of nanometer order are protruded.

"Tray", for example quartz (S i 0 _2), it is preferably produced by sapphire.

In the first invention, a small number of the first semiconductor layer, the second semiconductor layer, and the third semiconductor layer At least three layers are laminated to produce a group III nitride semiconductor film (lamination step). Next, nanopillars are manufactured by dry-etching the group III nitride semiconductor film (nanopillar manufacturing step). Finally, a group III nitride quantum dot can be manufactured by growing a new semiconductor in the gap between the nanopillars and growing the filling layer (filling step).

As the material constituting the “filled layer”, any one of the materials constituting the first semiconductor layer and the material constituting the third semiconductor layer can be selected and used. A group III nitride semiconductor different from any of the semiconductor layer to the third semiconductor layer is selected. Note that it is preferable to select, as the filling layer, a semiconductor having lower conductivity than the material of the second semiconductor layer. By doing so, it is possible to selectively apply a voltage to the quantum dots provided at predetermined positions. More specifically, a buffer layer such as A 1 N is formed on a substrate such as sapphire (for example, it can be manufactured by MOVPE method), and the first semiconductor layer is formed on the buffer layer by, for example, MOVPE method. The layer, the second semiconductor layer, and the third semiconductor layer are sequentially laminated to form a group III nitride semiconductor film (lamination step).

Next, nanopillars are manufactured by etching the metal nitride semiconductor film by dry etching. For example, 1 0- ⁴ P a orders placed vacuum etch chamber a pair of positive and negative electrodes (e.g., the parallel plate electrodes) Place II I-nitride semiconductor film on one of the upper surface of quartz etching chamber (S i O ₂ ) or sapphire is used as a tray for the negative electrode. After introducing a gas containing chlorine of 1 Pa to 5 O Pa, high frequency power is applied to the electrodes to generate plasma from a plasma generating gas, and the plasma is used to etch the group III nitride semiconductor film. Make nano villas. The dimensions of the fabricated nanopillars are mostly less than about 100 nm, and the spacing between adjacent nanopillars (gap) is on average from several tens of nm to about 100 nm. It can be. For this reason, it is possible to form the nano pillar and the gap repeatedly at a distance of about several tens nm to about 100 nm. If you that, will be approximately 1 X 1 0 ⁶ about nanopillars in 1 cm is configured, during 1 cm ^2, it is possible to configure to about 1 X 1 0 ¹¹ about the quantum dots. Furthermore, when a laminated layer is used as the second semiconductor layer, a structure of about 1 × 10 ¹² or more quantum dots is formed. It becomes possible.

A new group III nitride semiconductor is grown in the gap between the nano-villagers made of the group III nitride semiconductor thus formed (filling step). At this time, it is preferable to perform etching with plasma such as CF ₄ so as to completely remove the slow-etching substance from the surface of the nanopillar and contribute to the formation of a smooth filling layer. The filling method may be, for example, metal organic vapor phase epitaxy (MOVPE), hydride vapor phase epitaxy (HVPE), or molecular beam epitaxy (MBE). (molecular beam epitaxy)).

In addition, (1) lamination process, (2) nanopillar fabrication process, and (3) filling process are made into one set, and the process of (1) to (3) is repeated sequentially to produce quantum dots formed in multiple layers in the height direction. be able to.

According to the present invention, fine needle-like structures (nanopillars) can be easily formed, and quantum dots can be manufactured by filling the gaps between the nanopillars with a new group III nitride semiconductor. . The density of the dots this time, 1 0 ⁶ /. Group III nitride quantum dots of m ² to l 0 ¹² / cm ² can be provided.

According to the present invention, nanopillars can be easily formed on the surface of a group III nitride semiconductor film, and the gaps between the nanopillars are filled with a new group III nitride semiconductor, so that the group III nitride quantum can be efficiently produced. Dots can be manufactured.

Further, it is possible to manufacture a large-area light-emitting diode display or a large-area fluorescent display using a field emission cold cathode using the above-described group III nitride quantum dots. BRIEF DESCRIPTION OF THE FIGURES

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

FIG. 2 is a view showing a process of manufacturing a group III nitride quantum dot. FIG. 1A is a cross-sectional view of a substrate before stacking a group III nitride semiconductor, and FIG. 1B is a cross-sectional view when a group II nitride semiconductor is stacked. FIG. 3 is a diagram showing a process of manufacturing a group III nitride quantum dot. FIG. (C) is a cross-sectional view when nano-vias are formed by dry etching, and FIG. (D) is a cross-sectional view when a new group III nitride semiconductor is filled in the gaps between the nanopillars.

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

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

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

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

The symbols in the figure are nanopillar 50, sapphire 51, buffer layer 52, n-G a Ν (first semiconductor layer) 53, and InG a N (second semiconductor layer, Light-emitting layer) 54, p-InGaN (third semiconductor layer) 55, semiconductor structure having quantum dots 56, GAN (filled layer) 58, p-GaN (semiconductor) Layer) 59, group III nitride semiconductor film 60, electrodes 61, 62, multilayer quantum dots 70, group III nitride semiconductor 101, quartz substrate 102. 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 by the following embodiments or examples, and can be implemented in various modes without changing the gist of the invention. Further, 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 equipment includes an etching chamber 1, a high-frequency power supply 2, an exhaust device, and a plasma generating gas introduction device.

More specifically, for example, a pair of positive and negative parallel plate type electrodes 11 and 12 are installed in an etching chamber 1 made of stainless steel so as to face each other. Both electrodes are generally The high frequency power is applied to the cathode 12 while the anode 11 is kept at the ground potential. The cathode 12 is hit hard by the plasma gas and the temperature rises. For this reason, in order to cool the cathode 12, a hollow structure is provided so that cooling water can flow on the back side. The cathode 12 is connected to a high frequency power supply 2 of 13.56 MHz via a matching box 22 to control the plasma.

An exhaust pipe 3 is provided in the etching chamber 1. The exhaust pipe 3 is connected to an exhaust device (not shown) in which a dry pump, a turbo pump, and the like are combined. By driving the exhaust device, the internal space of the etching chamber 1 can be evacuated to, for example, 10 to ⁴ Pa or less. The pressure in the etching chamber 1 is adjusted by, for example, a pressure adjusting valve 33 provided in the middle of the exhaust pipe 3, and is always kept at a certain degree of vacuum.

The etching chamber 1 is further provided with gas introduction pipes 4a and 4b for introducing each plasma generating gas into the etching chamber 1 室. The other end sides of these gas introduction pipes 4a and 4b are connected to an external plasma generating gas source (not shown). More specifically, the etching chamber 1 has a first gas introduction pipe 4a for introducing an etching gas (for example, chlorine gas) and another gas (a first gas when necessary). And a second gas introducing pipe 4b for introducing a gas for performing dry etching by mixing with a gas. 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 內 as a plasma generating gas, the gas introduction pipe 44b is omitted or closed.

Next, an operation of forming a nanopillar by etching the group III nitride semiconductor film using the above dry etching apparatus will be described. In the following examples, n-GaN, InGaN, and pGaN are exemplified as semiconductors constituting the first to third semiconductor layers, respectively. The scope is not limited to this, and use a nitride semiconductor represented by the formula A 1 _X G a _y I n ^ N (0≤x≤l, 0≤y ^ l and 0≤x + y≤l) Can be. At that time, 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. As shown in FIG. 2A, the group III nitride semiconductor film is provided on the upper surface of a buffer layer 52 provided on the upper surface of a sapphire substrate 51, for example. On the upper surface of the buffer layer 52 (for example, A 1 N having a thickness of about 20 nm can be used), a first semiconductor layer 53 (for example, For example, n-GaN can be used.), The second semiconductor layer 54 (for example, InGaN can be used), and the third semiconductor layer 55 (for example, undoped Gn). a N or InG aN, p-type G aN or InG aN, or A 1 InG aN can be used.) Are formed (Fig. 2 (b)).

Here, the thickness of the first semiconductor layer 53 is about several hundreds to several thousand nm, and the thickness of the second semiconductor layer 54 (which eventually becomes a quantum dot and forms a light emitting layer) is about several nm. It is preferable that the thickness of the third semiconductor layer 55 is about several nm to about 100 nm. In addition, it is preferable that the band energy gap of the second semiconductor layer 54 is selected to be smaller than the band energy gap of the first semiconductor layer 53 and 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 such a group III nitride semiconductor film 60, each cathode 1 A quartz substrate 102 as a solid is placed on the upper surface side of 2, and a sample 101 in the form of a wafer, for example, is placed on or around the upper surface thereof. When the sample 101 is placed on the upper surface of the quartz substrate 102, the cross-sectional shape of the quartz substrate 102 should be larger than the cross-sectional shape of the sample 101, and the quartz substrate 102 is used as an etching gas. Keep exposed.

Then, by driving the exhaust device evacuated to the interior of the etching chamber 1 a 1 0- ⁴ P a order pressure of. After the degree of vacuum inside the etching chamber 1 is stabilized, the chlorine gas is introduced from the gas inlet pipe 4a into the internal space of the etching chamber 1 while being controlled by the mass flow controller 44a 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 adjust The internal pressure of the chucking chamber 1 is controlled to a predetermined pressure. When a voltage is applied from the high-frequency power supply 2 via 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.

The chlorine gas plasma sputters and etches the group III nitride semiconductor film 60 of the sample 101 while etching the quartz substrate 102 (nanofabric one manufacturing step). By the etching operation, nanopillars 50 are formed on the surface of the group III nitride semiconductor film 60, as shown in FIG. 3 (c). The diameter of the nanopillars 50 ranges from about 10 nm to about 200 nm. Also, the spacing between adjacent nanopillars 50 is about 100 nm on average. In addition, the diameter and the interval of the nanopillars 50 can be appropriately changed depending on the conditions at the time of etching. Next, as shown in FIG. 3D, a gap between the nanopillars 50 is filled with a new group III nitride semiconductor to form a filling layer 58 (filling step). As the filling method, the MO VPE method, the HVP E method, the MBE method and the like are mentioned as described above. When there is no need to provide the nano-pillars 50 on the entire surface of the group III nitride semiconductor layer 60, as shown in FIG. 4, consists of a mask 57 (e.g., S i 0 ₂ requires no place to advance the etching mask By performing the dry etching in the state where the process is performed, the nano pillars 50 can be formed only at desired positions.

Thus, a quantum dot (group III nitride quantum dot) 56 made of a group III nitride semiconductor can be manufactured. As shown in FIG. 6, a light emitting device can be manufactured by providing a pair of positive and negative electrodes 61 and 62 above and below a quantum dot 56. In this case, a semiconductor layer 59 (for example, p-GaN can be used) is further laminated on the upper surface side of the filling layer 58, and the electrode 61 is formed on the upper surface of the semiconductor layer 59. Is preferably provided.

In addition, from the state shown in FIG. 3 (d), on the upper surface side, a group III nitride semiconductor (eg, n—GaN, InGaN, and!) — GaN) composed of three new layers is provided. Are stacked to form a group III nitride semiconductor film, and the nanopillar fabrication process and the filling process are repeated for the semiconductor film in the same manner as described above. Can be easily manufactured. Example

Next, the present invention will be described with reference to examples. In each of the following examples, the above-described etching apparatus (FIG. 1) was used.

Example 1

On the sapphire 000 1> substrate, via a buffer layer 52, for example, n-GaN53 (corresponding to the first semiconductor layer in the present invention), InGaN54 ( A group III nitride semiconductor film 60 on which p-GaN 55 (which is harmful to the third semiconductor layer in the present invention) is grown. Was used as a sample 101 for etching.

Here, the thickness of n-Gan53 and p-gan55 was about 300 nm, and the thickness of InGa54 was about 20 nm. On the upper surface of the sample 10 1, for example, by RF sputtering, depositing a S i 0 ₂ at a thickness of about 300 nm, by conventional photolithography graphic techniques, <1 1 00> direction of 5 mu m line and A space pattern was prepared and used as an etching sample 101.

A quartz substrate 102 was set on the stage of the etching chamber 1. An etching sample 101 was placed around or on the upper surface of the quartz substrate 102.

Was then evacuated etching chamber 1 to 5 X 1 0- ⁴ P a vacuum pump. After the degree of vacuum in the etching chamber 1 was stabilized, chlorine gas was introduced into the etching chamber 1 from the gas introduction pipe 4a at a flow rate of 30 ml / in while being controlled by the mass flow controller 44a. At the same time, the inside of the etching chamber 1 was evacuated by a vacuum pump, and the pressure regulating valve 33 was adjusted to control the pressure inside the etching chamber 1 to 6 Pa.

After confirming that the degree of vacuum in the etching chamber 1 was stable, a voltage was applied from the high-frequency power source 2 to generate plasma between the electrodes 11 and 12 and 100 W (the area was 1 Dry etching was performed for about 4 minutes under the condition of 77 cm ² ).

After the dry etching, the sample No. 101 was taken out of the etching chamber 1, and the etched surface was observed with a scanning electron microscope (SEM). FIG. 5 shows a photograph showing the structure of the etched surface of the group III nitride semiconductor film observed by SEM. The manufacturing process of nanopillars according to this embodiment can be considered as follows, for example. Wear. That is, chlorine ions in the plasma collide with the quartz substrate in the vicinity of GaN, and S i 0 ₂ jumps out into the plasma due to the sputtering effect. Some of the SiO ₂ is likely to be ionized and redeposited on the negatively biased GaN film. Here, when S i 0 ₂ is compared to G a N, since one degree and low 20 minutes 10 minutes Etsuchin Great to chlorine gas plasma, since acting as minute masks, Sample 1 0 1 A minute uneven structure is formed on the surface.

When locations S io ₂ becomes slightly convex adhere than the recess, considered as the probability of S io ₂ Subsequently the electric field becomes high adheres increases. It is thought that the nanopillar structure was obtained as a result of the re-deposition of Sio _{2 and} the etching with chlorine gas plasma repeatedly proceeding in parallel. However, the results of the XPS analysis showed that Si was detected on sapphire, but not on GaN. Therefore, at present, in the method of the present embodiment, the manufacturing process of the nanopillars is not always clear.

The nanopillar structure has a thickness of + nn! The height was about 100 nm, and the height was about 500 nanometers. In addition, the density of the nanopillars was on the order of 10 ⁶ to ^ "!!! ^2. It was found that the height of the nanopillars was greatly dependent on the etching time.

The gap between the nanopillar structures fabricated in this way was filled with a new group III nitride semiconductor (G a N) by, for example, MOV PE method to form a filling layer 58 (Fig. 3 (d) reference). The conditions at this time, trimethyl gallium (TMG) flowed at 48 i mol / min, the _{NH 3 11 / min, 1 000} ° C, was 300 Torr. In addition, from the state shown in FIG. 3D, n-GaN, InGaN, and pGaN are newly laminated on the upper surface side, and the laminated semiconductor film is The multilayer quantum dot 70 shown in FIG. 7 can also be manufactured by repeating the operation of fabricating the nano-village by the dry etching operation and filling the gap between the nano-pillars.

As described above, according to the present embodiment, nano-pillars 56 can be easily formed on the surface of the group III nitride semiconductor film 60, and the gaps between the nanopillars 56 are filled with the new group III nitride semiconductor. This makes it possible to efficiently manufacture the group III nitride quantum dots 56. Also, by utilizing such a group III nitride quantum dot 56, It is also possible to manufacture large-area light-emitting diode displays and large-area fluorescent displays using field emission cold cathodes.

In particular, when a multi-quantum structure in which semiconductor layers having different hand gap energies and having a height of about 1 nm to about 100 nm are stacked is used as the second semiconductor layer, a group III nitride quantum dot having a multilayer structure is used. In such a multi-layer quantum dot, the quantum dots are almost vertical on the sides and are uniform in height, so that the quantum dots excite each other, enabling efficient light emission Becomes

Claims

The scope of the claims

1. Each of the following steps: (1) a laminating step of laminating at least three layers of a first semiconductor layer, a second semiconductor layer, and a third semiconductor layer to produce a group III nitride semiconductor film; A nano-pillar manufacturing process for manufacturing nanopillars by dry-etching the group-III nitride semiconductor film; and ③ a filling process for growing a new semiconductor in a gap between the nano-pillars and growing a filling layer. Manufacturing method of group III nitride quantum dots.

2. The nanopillar manufacturing step of the above (1) is performed in a state where a slow-etching material having a smaller etching rate than that of the group III nitride semiconductor film is present on the surface of the group III nitride semiconductor film. 2. The method for producing a group III nitride quantum dot according to claim 1, wherein the nitride semiconductor film is dry-etched.

3. The bandgap energy of the second semiconductor layer is smaller than the bandgap energy of the first semiconductor layer and the bandgap energy of the third semiconductor layer. 3. The method for producing a group III nitride quantum dot according to any one of 2.

4. The multilayer quantum dot according to any one of claims 1 to 3, wherein the multilayer quantum dot is manufactured by repeating the above (1) lamination step, (2) nanopillar manufacturing step, and (3) filling step. Method for producing group III nitride quantum dots.

5. quantum dot distribution density of 1 0 ⁶ Bruno 0: ₁ 11 ² to 1 0 ¹² Zc III nitride device according to feature that m is ^2.