JPH101304A - Photoexcited production of four-coordinated BN material - Google Patents

Abstract

(57) [Summary] [Object] To provide a method for producing four-coordinate bonded boron nitride, that is, cBN, wBN, etc., without using the conventional high pressure and high temperature conditions. The raw material which has been subjected to untreated or doped treatment such as boron nitride or hBN by sp ² hybrid bonding is irradiated with high energy density light of infrared ultra-short pulse resonating in its out-of-plane vibration mode. Produce coordination bonded boron nitride. The structure and function of the semiconductor device are created by the accompanying processing method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to (a) a light-emitting diode and an electroluminescent material used in technologies such as illumination, display, optical recording, optical diagnosis, and phototherapy, and (b) a neutron detecting semiconductor device used in nuclear-related technologies. material,
(C) The present invention relates to a method for producing a BN semiconductor material as a high-temperature various semiconductor element material or the like in technologies such as automobiles and resource search, and a super-hard BN material for cutting and grinding in the processing of metals and the like.

[0002]

2. Description of the Related Art Sp ^three- phase BN represented by cBN is mainly used as a super-hard material next to diamond for cutting tools such as metals. In recent years, the possibility of technology in a region where ordinary materials are not used as semiconductor materials has been shown. The superhard material exclusively ultra high pressure technology, around 50,000 atm by mixing the various flux material that has been called the raw material and the catalyst sp ² phase material, such as hBN, to precipitate the dissolved crystals at around 1700 ° C. Made by the way. In recent years, a method has been attempted in accordance with the method of producing a vapor from a gas phase, which has been demonstrated for diamond, mainly for a semiconductor material, but has not yet been realized.

[0003]

SUMMARY OF THE INVENTION It has been difficult to produce semiconductor materials by conventional methods. In that case, it is necessary to control the purity, composition, and structure according to the purpose, and it is often necessary to form a film. However, in the current high-pressure high-temperature method described in the preceding paragraph, since the crystal is formed in a small enclosed space, most of the control techniques for manufacturing the semiconductor cannot be used. In addition, since it is naturally precipitated from the flux, it is difficult to control the composition and improve the purity, and it is difficult to prevent the contamination of the flux components and the like. The present invention enables the production of semiconductor materials that require high purity and a high degree of control over composition and structure by providing a method of making four-coordinated (sp ³ phase) BN material in a completely different way than before. It also aims to provide a manufacturing method that opens up new application possibilities for cemented carbide materials.

[0004]

A transition from hBN, which can be said to be a representative of the sp ² phase, to one wBN of the sp ³ phase will be described as an example. The same principle can be applied to other cases, such as conversion from rBN to cBN. hBN (7) A _2u mode is

FIG. 1 is a diagram that vibrates in the <111> direction on the C axis as indicated by an arrow to the right of FIG. A wBN on the left side of the figure is formed by forming a bond such that the arrows of the vibrations approach each other. The present invention excites the amplitude of this vibration to a large value so that
The transition to the phase. The conventional method, so to speak, did it with heat. It is effective to perform the above light irradiation under a pressurized condition in order to promote the transition. In the present invention, a sp ² phase sintered body such as hBN or the like, or a material obtained by doping, mixing, and vapor-depositing a dopant is used as a raw material. By doping, a p-type or n-type semiconductor, a light-emitting material, or the like can be manufactured. A planar structure or the like can be manufactured by setting the position of the raw material, the formed raw material, or the raw material obtained by depositing a dopant with a pattern, and irradiating the light. Since the light absorption used in the present invention is strong and is absorbed near the surface of the raw material, a film-shaped four-coordinate bonding material can be produced.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described by taking as an example the production of wBN from hBN as in the previous section. The process of exciting and transferring the vibration according to the present invention occurs as follows. Excitation by light is a quantum process. When light having a wavelength of 1.28 × 10 ⁴ nm that resonates with the A _2u mode is applied, one normal vibration state is excited. The state tries to relax to another vibration mode, but if light comes soon, it rises to a higher excited state. To climb the staircase of the vibrational quantum state to the top of the potential of the transition state at the boundary between the two phases and to cross it (this is equivalent to increasing the amplitude and forming a coupling) It must overcome the relaxation from each vibrational level and excite upward while each is in the excited state. Therefore, a pulsed laser beam having a time width of substantially ps or less and having sufficient energy within a relaxation time width expected to be about ps (10 ⁻¹² seconds) is used. The energy required for excitation between the vibrational states is smaller for higher excitation states (vibration anharmonicity). The pulsed light has a spectrum width based on the uncertainty principle. Above A _2u mode 1.28 × 10
^On the side of ⁴ nm, a light pulse of 1 ps width is 5.2 × 10
It has a spectral width of nm, and is 5.2 × 10 ³ n at a limit of the short-time width that can be realized is approximately 10 fs (10 ⁻¹⁵ s).
m spectral width. This width naturally falls within a range that is not large enough to compensate for the wavelength shift of the vibration excitation light due to anharmonicity and to excite other vibration modes. When other modes are excited, the selectivity of the vibration that causes the transition to proceed is reduced, and the efficiency of the transition is impaired by exciting the reverse vibration. Assuming that the number of vibration levels reaching the peak of the transition state is N, the concentration in that state is proportional to the Nth power of the incident energy. From the above considerations, it can be seen that it is desirable to condense light having a width of about 1 ps or less and a large energy per pulse centering on the wavelength of the _A2u mode and irradiating with high energy density. The density of wBN (5 hBN crystals is 3.49 × 10 ³ kg / m ³ and 2.26 × 10 ³ kg / m ³ , respectively)
m is ^3. Therefore, the transition from the h-phase to the w-phase is promoted under pressure according to the Le Chatelier rule, and it is desirable to carry out the irradiation under pressure if possible for the purpose.
The stable phase at normal pressure is not the h phase,
Phase, although the theory of the insole is sp ³ phase cast has been filed, the present invention does not depend on the how to solve this problem. The doping is performed by performing the above-described light treatment on a doped raw material, a raw material in which a dopant is mixed, or a raw material obtained by depositing a dopant on a sample. The formation of a pn junction, point-like or linear element structure, etc. is performed by setting the irradiation position of the light beam and setting the scanning or irradiation time in combination with the processing of the sample. The processing of this sample is performed by vapor-depositing a dopant in a pattern intended for molding and forming the raw material. This sample processing is performed in a time series according to the purpose, such as before or after light irradiation, or alternately. Light absorption by the lattice vibration mode, which is the core of the present invention, is strong and is absorbed by the surface layer of the raw material.
Further, as described above, the light intensity dependence of the transition is extremely strong. Therefore, the four-coordinate bonding material is formed in a film shape.

[0006]

【Example】

Embodiment 1

FIG. 2 shows an example of a basic manufacturing apparatus. Raw material 1. Used was 10 mm × 10 mm × 2 mm pBN (small hBN was sintered). 7. A table that moves it in two axes x and y Fixed on top. 200mmφ × 20
1. 0 mm container We installed in. A 20 mmφ × 5 mm (7) Si window was placed on the container at a position corresponding to the upper part of the central sample. The inside of the container was filled with one atmosphere of nitrogen. As a laser light source, a parametric oscillation type tunable ultrashort pulse laser was used. It was tuned to 1.28 × 10 ⁴ nm. Pulse width 100fs, pulse energy 0.8
3. Operate at μJ, 10 Hz, concave mirror And focused on the sample, thereby obtaining an energy density of about 0.1 J / cm ² per pulse. 5. Is a light deflector and the base is 8. Used together with the structure. Irradiation was performed for 10 minutes while fixing the laser beam, and the luminescence spectra of the irradiated part and the non-irradiated part were measured. Light emission due to contamination C (pBN has this contamination) is observed in the non-irradiated portion, but wB
A spectrum having a structure on the 400 nm side often observed in N was observed, and a transition from the h phase to the w phase was confirmed.

Example 2 Half of the pBN sample was covered with aluminum foil and Si
, Followed by deposition of Be over the portion, processing for 1 hour while scanning the laser beam in a 5 mm square with the boundary in the middle, lightly polishing the surface to remove the deposit, and removing the boundary joint. An electrode was attached to the opposite side, and an EBIC (electron beam induced current) image of this boundary was observed to confirm the existence of a space charge layer. This indicates that the intended doping and pn junction formation were achieved.

[Embodiment 3] Irradiation with the beam fixed for 10 minutes

FIG. Was moved 30 μm in the x direction and the same irradiation was performed five times. By luminescence observation with a scanning electron microscope, point-like emission images arranged every 30 μm were observed, and the spectrum was unique to the four-coordinated BN. It has been shown that such a BN with a small structure can be manufactured.

[0007]

As described above, a diamond material having properties similar to those of the four-coordinate bond BN has been used as a semiconductor material since the vapor phase method has been realized. However, although it has been found that BN is superior to diamond for many semiconductor performance items, it has not been realized due to the conventional manufacturing method. The present invention enables the realization of excellent semiconductor functions inherent to BN. It can be said that the possibility of realizing new possibilities even with cemented carbide materials has been opened.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the principle of the present invention. sp ² bond B
The crystal structure and lattice vibration of the representative hBN of N, the crystal structure of wBN, and the chemical bond of these two are shown. Both are projections onto a plane containing the C axis and a group of bonds perpendicular to it. The big circle is the atom on the paper, and the small circle is the atom at the back. If black is B, white is N. The line connecting the circles is a strong covalent bond. Weak van der Waals coupling between hBN planes. Arrows indicate displacement of A2u mode vibration.

[Explanation of symbols]

 1, 2, and 3 are the hexagons of hBN and the honeycomb mesh surface.

FIG. 2 is a schematic view of an apparatus used in the production method of the present invention.

[Explanation of symbols]

 1. Raw materials 2. Container 3. Laser and its power supply Reflecting mirror 5. Light deflecting element (deflects in two directions, X and Y) 5 '. 5. Driver of 6. Window 7. Atmosphere adjustment device 8. X, Y bidirectional fine motion sample stage 8 '. 8. Driver of 8 Control computer for the whole system

Claims (5)

[Claims] 1. (a) BN consisting of bonds by sp ² hybrid orbitals, that is, hBN (hexagonal BN), rBN (rhombohedral B
N), pBN (pyrolysis BN), tBN (turbulent structure B
N), a-BN (amorphous BN), (any of these hereinafter referred to as sp ² phase), powder, sintered body, one of the single crystal as a raw material, from (b) Part sp ² hybrid orbital S by irradiating an ultrashort pulse laser beam that resonates with a vibration mode displaced perpendicularly to the plane containing the coupling
p ³ cBN consisting binding by hybrid orbital (cubic BN)
Alternatively, a method for producing a four-coordinate bond BN (hereinafter, referred to as sp ³ phase) material such as a wBN (wurtzite BN) material. 2. A group 11 element such as Be or Mg as a raw material;
Group IV elements such as C and Si, group VI elements such as O and S, other optically active transition metals, rare earth elements, etc., alone or in combination, each having 10
^{2. The} method according to claim 1, wherein a material containing dope, vapor deposition or mixture in a molar ratio ^of-(1-8) is used as a raw material. 3. The method according to claim 1, wherein the raw material is pressurized in a pressure vessel. 4. The method according to claim 1, wherein the irradiation position of the laser beam is controlled within the irradiation surface to form and control the composition and structure, or such surfaces are stacked. 5. The method according to claim 1, wherein an annealing step is inserted into the laser beam irradiation step.