JPH06140669A - Light emitting element and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide compatibility with silicon integrated circuit process and highly efficient light emitting property by forming a light emitting element, starting with the quantum fine line of silicon having p-n junction, and implanting electrons and positive holes into the junction area. CONSTITUTION:A quantum fine line 3, 0.01mum or under in diameter dimensions is used as a light emitting element. And, in the basic constitution consisting of the quantum fine line 3 made on a substrate 1 through an insulating film 2, an n region 6 and a p region 7 are made in the quantum fine line 3. When both ends of each region 6 and 7 are connected to electrodes 4 and 5, respectively, the electrons implanted from the electrode 4 and the positive holes 5 implanted from the electrode 5 are recoupled at the p-n junction being the junction face between the region 6 and the region 7. That is, a silicon light emitting element can be materialized, making use of the high quantum efficiency of the p-n junction being made in the quantum fine line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra high density, ultra high speed silicon light emitting device and a method of manufacturing the same.
The present invention relates to a light emitting device formed of a silicon quantum wire formed by arranging a plurality of atoms in one row, in a plurality of rows in a plane or in a three-dimensional manner, or in a circular or spherical order or randomly arranged, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventional semiconductor light emitting devices have been composed of so-called compound semiconductors having a direct transition characteristic such as gallium arsenide. The reason for this is that, for example, in an indirect transition semiconductor such as silicon, the light emission efficiency is extremely low, and it is impossible to obtain a light emission characteristic of a practical level by a normal current injection method. Therefore, when a light emitting element is required, it has been unavoidable to use a compound semiconductor having a direct transition characteristic. For this reason, an information processing element made of a silicon integrated circuit and a light emitting element made of a compound semiconductor are formed on the same chip. It was extremely difficult to accumulate. As one means for solving this, a so-called gallium arsenide on silicon for forming a compound semiconductor on silicon, and a light emitting element composed of a superlattice of germanium and silicon have been proposed, but the quality of crystals and the like have not yet been put to practical use. The current situation is that the level has not been reached. Further, since there is a problem in compatibility with silicon integrated circuit technology such as process temperature, there are many technical problems to be solved before practical use.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to overcome the above-mentioned limitations of the prior art, and is a silicon light-emitting device having an ultrafine silicon quantum wire structure that is completely compatible with silicon integrated circuit technology and a method thereof. A manufacturing method is disclosed. For example, silicon quantum spheres produced by the anodizing method have been reported to have a luminous efficiency due to the quantum confinement effect as the size shrinks, and a light emission phenomenon due to photoexcitation at a light wavelength of about 500 nm has been reported. No light emission due to injection can be expected. The light emitting device by current injection is an essential technology for high performance information processing or large capacity communication in the future.

[0004]

In the present invention, as a means for solving the above problems, a quantum wire having a diameter of 0.01 μm or less is used as a light emitting element. If a pn junction is formed in this quantum wire and a current is injected, electrons and holes are recombined at the pn junction, and a highly efficient light emission phenomenon occurs.

[0005]

The basic structure of the quantum wire pn junction disclosed in the present invention and its operation will be described. FIG. 1 is a sectional view showing the basic structure of the present invention. In a basic structure composed of quantum wires 3 formed on a substrate 1 with an insulating film 2 interposed therebetween, an n region 6 and a p region 7 are formed in the quantum wires 3 and electrodes 4 and 5 are formed on both ends of each region. When connected, the electrons injected from the electrode 4 and the holes injected from the electrode 5 are recombined at the pn junction which is the junction surface between the regions 6 and 7.

Pn formed in an ordinary silicon semiconductor
At the junction, the recombination efficiency is extremely low because the band structure is an indirect transition, and almost no luminescence phenomenon can be observed. However, in the pn junction formed in the quantum wire 3, a quantum effect peculiar to a minute structure appears and the band structure changes, and due to this carrier confinement effect, a highly efficient light emission phenomenon can be observed even in silicon.

That is, the essence of the present invention is to realize a silicon light emitting device by utilizing the high quantum efficiency of a pn junction formed in a quantum wire. Further, the present invention discloses a method of manufacturing a quantum structure that enables the high efficiency silicon light emitting device as described above.

[0008]

EXAMPLES The present invention will be described in detail below based on examples.

(Embodiment 1) FIG. 2 schematically shows the structure of a light emitting diode. An n-type semiconductor region 11 and a p-type semiconductor region 12 are formed in the quantum wire and connected to the extraction electrodes 14 and 15, respectively. Electrons from the electrode 14,
When holes are injected into the quantum wires from the electrode 15, the electrons and holes are recombined at the pn junction surface 13 existing at the interface between the regions 11 and 12. In a normal silicon semiconductor, energy associated with recombination is observed as heat because it is an indirect transition, but a light emission phenomenon is observed in a quantum wire with a diameter of 10 nm or less because the band structure changes.

When the diameter of the quantum wire is 5 nm or less, the luminous efficiency is particularly improved and the central wavelength of light emission is shortened. For example, when the diameter is 5 nm, the center wavelength is 550 nm, but when it is 3 nm, the center wavelength is 500 nm. The full width at half maximum of the emission spectrum is about 20 nm. The efficiency was about 10%.

The impurity concentration of the n-type region 11 must be 10 ¹⁹ / cm ³ or more, and the impurity concentration of the p-type region 12 must be 10 ¹⁹ / cm ³ or more. This is because it is necessary for the light emission phenomenon that the carriers are degenerated in both the p region and the n region. Impurity concentration 1
When it was 0 ²⁰ / cm ³ or more, the luminous efficiency became a practical value.
Further, the efficiency could be further improved by lowering the temperature.

The inventors' studies have shown that the steepness of the carrier distribution at the pn junction surface determines the light emission efficiency. The width of the transition region from the n region to the p region is 100
No emission phenomenon was observed above nm, and high emission efficiency was obtained with a dimension of about 10 nm or less. This phenomenon is also considered to be caused by the quantum effect. That is, it was found from the study by the inventors that the effect of confining carriers in the quantum wire appears from a dimension of about 10 nm to 20 nm.

(Embodiment 2) This embodiment discloses a laser having a quantum wire structure. Fig. 3 shows n in the quantum wire.
A type semiconductor region 11 and a p-type semiconductor region 12 are formed and connected to the extraction electrodes 14 and 15, respectively. When an electron is injected from the electrode 14 and a hole is injected from the electrode 15 into the quantum wire, p− existing at the interface between the regions 11 and 12 is injected.
The electrons and holes are recombined at the n-junction surface 13. Along with this recombination, a light emission phenomenon was observed from the pn junction surface. When this structure is placed in the reflecting mirrors 16, laser emission corresponding to the distance between the reflecting mirrors occurs. In this embodiment, the distance between the reflecting mirrors is 20.
By setting the thickness to 00 nm, luminescence having a sharp peak at 500 nm could be observed.

(Embodiment 3) This embodiment discloses a multiple emission laser which collects light emission from a plurality of atomic thin wires in order to increase the emission intensity. FIG. 4 shows a state in which an n-type semiconductor region 11 and a p-type semiconductor region 12 are formed in an atomic thin wire and connected to the extraction electrodes 14 and 15, respectively. When an electron is injected from the electrode 14 and a hole is injected from the electrode 15 into the quantum wire, pn existing at the interface between the regions 11 and 12 is injected.
The electrons and holes are recombined at the bonding surface 13. Here, by providing a plurality of atomic thin wires and a plurality of pn junctions 13 formed therein, the emission intensity of the laser becomes as strong as the number of atomic thin wires. Laser oscillation occurs by providing the reflecting mirrors 16 at both ends. In this case, laser oscillation having a peak intensity at about 530 nm could be realized as shown in FIG.

(Embodiment 4) This embodiment discloses a method for forming a quantum wire using the surface characteristics of a silicon oxide film deposited by a CVD method. FIG. 6A shows a state where the concave portion 22 is formed in the substrate 21. FIG. 6B shows a state in which a trench 24 is formed by depositing a silicon oxide film 23 by the substrate-like CVD method having such a structure and further etching it with a diluted hydrofluoric acid aqueous solution. Such a trench 24
The reason why is formed is that the surface of the silicon oxide film deposited by the CVD method is stabilized, so the inside of the trench is gradually filled with the silicon oxide film, and finally the two surfaces from the left and right meet and are completely filled. This is because the surfaces are not chemically completely bonded to each other even if they appear to be formed, and the interface is rapidly etched when the surface is etched with an aqueous solution of hydrofluoric acid. Therefore, the width of the trench 24 can be controlled by using a sufficiently dilute etching solution.

Such a phenomenon generally occurs in the deposited layer of the insulating film and is not observed in the semiconductor such as polycrystalline silicon. This is considered to be due to the difference in the bond state between atoms. FIG. 6C shows a state where the quantum wires 25 are realized by depositing polycrystalline silicon on the thus prepared substrate by the CVD method and etching by reactive ion etching. The quantum wires 25 are made of tungsten, molybdenum,
A metal such as aluminum can also be used. Figure 6
(D) shows a state in which the protective film 26 is coated on the quantum wire structure thus configured. As the composition of the protective film 26, a dense insulating film such as a silicon oxide film or a silicon nitride film is suitable.

A so-called RCA consisting of an aqueous ammonia solution and a hydrogen peroxide solution is formed by forming a recess of 100 nm in depth and 100 nm in width on an n-type (111) surface, 10 Ωcm silicon wafer by electron beam lithography and microwave plasma etching. The surface was thoroughly cleaned with a cleaning solution to clean it. A silicon oxide film with a thickness of 70 nm is formed by the low pressure CVD method.
It was deposited and the recess was completely filled with silicon oxide. After preparing such a structure, etching was performed for 10 seconds with an etching solution prepared by diluting a 50% hydrofluoric acid aqueous solution with pure water 100 times, and washed with ultrapure water for about 10 minutes. By this etching, only the part where the surface of the silicon oxide film meets was rapidly etched, and a trench having a width of 5 nm and a depth of 30 nm could be formed. When the silicon oxide film deposited by the low pressure CVD method is sufficiently thick, it is also effective to remove the surface of the silicon oxide film to some extent by reactive ion etching or microwave plasma etching. Then, polycrystalline silicon is deposited to a thickness of 50 nm by a low pressure CVD method using monosilane (SiH ₄ ) as a source gas, and anisotropically etched by a microwave plasma etching method for about 50 nm. A fine line of crystalline silicon was formed.

It goes without saying that the material of the substrate 21, the material of the insulating film 23, the thickness, the material of the quantum wires 25, etc. are not limited to those exemplified here in this embodiment. The substrate 21 is an intercalation compound such as graphite or molybdenum disulfide, a semiconductor such as gallium arsenide, an insulating material such as quartz, or a material capable of forming an electrically insulating material thereon. If so, it can be used in principle.
Although silicon oxide is generally suitable for the insulating film 23,
An insulating material such as silicon nitride or aluminum oxide can be used. The material of the quantum wire 25 is not limited to those listed here as long as it is a conductor.

After depositing polycrystalline silicon, doping n-type impurities and p-type impurities respectively and activating them by heat treatment or the like makes it possible to form a pn junction in a desired quantum wire structure. In the embodiment described here, an appropriate combination of process parameters can be selected by a skilled researcher.

[0020]

As is apparent from the above embodiments, according to the quantum wire laser of the present invention, as compared with the conventional compound semiconductor laser, a silicon quantum wire laser compatible with the silicon integrated circuit process can be obtained. This is feasible, and by using this structure, an optical integrated circuit can be easily realized on a silicon integrated circuit, so that there are immeasurable practical impacts.

[Brief description of drawings]

FIG. 1 is a diagram showing the principle of a quantum wire light emitting device according to the present invention.

FIG. 2 is a diagram showing an embodiment of a light emitting diode according to the present invention.

FIG. 3 is a diagram showing an embodiment of a light emitting laser according to the present invention.

FIG. 4 is a diagram showing an embodiment of a multiple emission laser according to the present invention.

FIG. 5 is a diagram showing an emission spectrum from a quantum wire light emitting element.

FIG. 6 is a diagram showing an example of a method of realizing a quantum wire light emitting device.

[Explanation of symbols]

1, 21 ... Substrate, 2, 23 ... Insulating film, 3, 13 ... pn
Junction, 6, 11 ... N-type region, 7, 12 ... P-type region, 4,
5, 14, 15 ... Electrodes, 16 ... Reflector, 25 ... Quantum wires.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takami Sudo 1-280 Higashi Koikeku, Kokubunji, Tokyo Inside Central Research Laboratory, Hitachi, Ltd. (72) Toshiyuki Yoshimura 1-280 Higashi Koikeku, Kokubunji, Tokyo Hitachi Ltd. Central Research Center

Claims (6)

[Claims] 1. A light emitting device comprising a silicon quantum wire having a pn junction and injecting electrons and holes into the junction region. 2. The light emitting device according to claim 1, wherein the silicon quantum wire has a diameter of 10 nm or less and a pn junction is formed in the length direction. 3. The light emitting device according to claim 1, wherein a plurality of silicon quantum wires are provided in parallel. 4. A light emitting device comprising a silicon quantum wire having a pn junction and a reflecting mirror arranged so as to sandwich the junction, and injecting electrons and holes into the junction. 5. The light emitting device according to claim 4, wherein a plurality of silicon quantum wires are provided in parallel. 6. A structure comprising a substrate and a groove having a sufficiently small size formed in the substrate, a step of depositing an insulating film in the groove, and a step of etching the insulating film to provide a minute opening. A method for manufacturing a silicon light emitting device, comprising at least a step of forming a conductor in the opening.