JP2011003361A - Electron emission element, and manufacturing method of electron emission element - Google Patents

Abstract

An electron-emitting device capable of emitting electrons under a relatively low temperature and a low extraction voltage, and a method for manufacturing the electron-emitting device are provided.
An electron-emitting device includes an epitaxial film including a diamond crystal and a diamond protrusion having a surface including a region where the epitaxial film is formed. The diamond protrusion 5 has a shape that can be accommodated in a cylinder having a bottom surface with a diameter of 100 μm and a height of 1000 μm. Further, the electron-emitting device 2 further includes a metal film 7 provided on the epitaxial film 6. The epitaxial film 6 contains an n-type or p-type dopant.
[Selection] Figure 1

Description

  The present invention relates to an electron-emitting device and a method for manufacturing the electron-emitting device.

  Conventionally, electron gun chips such as ZrO / W or LaB6 have been used in electron microscopes, electron beam drawing apparatuses, transmission electron microscopes, and the like. Since such an electron-emitting device such as an electron gun chip is generally used at a high temperature of 1800 degrees Fahrenheit (Non-Patent Document 1), electrons emitted from the electron-emitting device due to Fermi distribution spread and phonon scattering are used. Energy is greatly dispersed. On the other hand, an electron-emitting device using diamond has been developed. Since the work function of diamond is relatively low, an electron-emitting device using diamond can emit electrons even at a relatively low temperature. In particular, the effectiveness of a diamond film doped with n-type impurities is known (Patent Document 1). Further, when the diamond film is S-doped (Non-Patent Document 2), B-doped (Non-Patent Document 3), Non-doped (Non-Patent Document 4), or N-doped (Non-Patent Document 3). In any case of Patent Document 5), there is a report that the work function is low and electron emission is possible at a relatively low temperature. Furthermore, it has been reported that an n-type diamond film doped with Li also has a relatively low activation energy (Non-patent Document 7).

JP 2007-095478 A JP 2005-310724 A JP 2008-210775 A JP 2005-044634 A JP 2008-199936 A

J. Vac. Sci. Technol. B 3 (1), Jan / Feb (1985) 220 Phys. Rev. B, 60, 4 (1999) R2139 J. Vac. Sci. Technol. B 22 (3), May / Jun (2004) 1349 Diam. Relat. Mater. 11, 12 (2002) 1897 Nature, 393, 4, June (1998) 432 Thin-Film Diamond I, Semiconductors and Semimetals Vol. 76, Chapter3, Elsevier Inc., 2003 Appl. Phys. Let., 81, 5, July (2005) 232102 Appl. Phys. Let., 82, 17, Apr (2003) 2904

  Based on various research results on the electron emission characteristics of diamond as described above, it is desired to develop an electron gun tip that can be used even at a relatively low temperature and a low extraction voltage. Therefore, an object of the present invention is to provide an electron-emitting device capable of emitting electrons even under a relatively low temperature and a low extraction voltage, and a method for manufacturing the electron-emitting device.

  An electron-emitting device according to the present invention is an electron-emitting device including an epitaxial film containing a diamond crystal and a diamond protrusion having a surface including a region where the epitaxial film is formed. The diamond protrusion has a diameter of 100 μm. It has the shape which can be accommodated in the cylinder which has a bottom face of and a height of 1000 micrometers. As described above, the electron-emitting device of the present invention has a configuration in which an epitaxial film including a diamond crystal is formed on a diamond protrusion, so that a relatively low temperature and a low extraction voltage can be obtained by a relatively low work function of diamond. Even in the original, electron emission becomes possible.

  The electron-emitting device of the present invention preferably further comprises a metal film provided on the epitaxial film, and the metal film is preferably joined to the epitaxial film. The electron-emitting device can be used as an electron gun by passing a current through the metal film.

In the electron-emitting device of the present invention, the epitaxial film contains an n-type dopant containing one or more elements of Li, P, S, and N, and the concentration of the n-type dopant in the epitaxial film is 1 × 10 ^13. It is ˜1 × 10 ²² cm ⁻³ and the activation energy of the epitaxial film is preferably 0.10 to 4.0 eV. Thus, since the epitaxial film has a relatively low activation energy by containing the dopant, the relatively low work function of diamond and the relatively low activation energy achieve sufficient electron emission performance. it can.

In the electron-emitting device of the present invention, the epitaxial film contains a p-type dopant containing an element of B, and the concentration of the p-type dopant in the epitaxial film is 1 × 10 ¹³ to 1 × 10 ²² cm ^−3. The activation energy of the film is preferably 0.30 to 2.0 eV. Thus, since the epitaxial film has a relatively low activation energy by containing the dopant, the relatively low work function of diamond and the relatively low activation energy achieve sufficient electron emission performance. it can.

  In the electron-emitting device of the present invention, the epitaxial film includes a first layer and a second layer, and the first layer includes an n-type dopant including one or more elements of Li, P, S, and N. And the second layer contains a p-type dopant containing an element of B, the first layer is formed on the surface of the end of the diamond protrusion including the tip surface, and the second layer The second layer is formed on the first layer, or the second layer is formed on the surface of the end portion of the diamond protrusion including the tip surface, and the first layer is formed on the second layer. It is preferable that the following layer is formed. Thus, since the epitaxial film includes a pn junction, electron emission can be controlled using a bias voltage.

  In the electron-emitting device of the present invention, it is preferable that the diamond protrusion has a flat front end surface that can be accommodated in a square region having a side of 1 μm and a side surface having an area larger than the area of the front end surface. Thus, the diamond protrusion has an elongated shape.

  In the electron-emitting device of the present invention, it is preferable that the end of the diamond protrusion including the tip surface has a stepped shape. As described above, the end of the diamond protrusion can have various shapes.

  In the electron-emitting device of the present invention, it is preferable that the plane orientation of the region included in the surface of the diamond protrusion and where the epitaxial film is formed is (111), (112) or (100). With such a plane orientation, the epitaxial film can be satisfactorily formed.

  In the electron-emitting device of the present invention, the diamond protrusion preferably includes at least one type of diamond crystal of type Ib, IIa, and IIb. In the case of such a crystal structure of the diamond protrusion, an epitaxial film containing an n-type dopant can be formed on the surface of the diamond protrusion.

  In the electron-emitting device of the present invention, it is preferable that a base portion integrated with the diamond protrusion is further provided, and the diamond protrusion is preferably formed at one end of the base portion, and the base portion preferably has a heteroepitaxial structure. . Since the diamond protruding portion is formed on the base portion, the diamond protruding portion can be easily moved through the base portion.

  The method for producing an electron-emitting device of the present invention has a shape capable of including a cylinder having a bottom surface with a diameter of 100 μm and a height of 1000 μm, and is a diamond of any one of the Ib, IIa, and IIb types Polishing one end portion of the diamond base material containing crystals into a mesa shape, and etching the end portion of the diamond base material that has become a mesa shape, so that it can be accommodated in a square region having a side of 1 μm. Forming a diamond protrusion having a tip surface and a side surface having an area larger than the area of the tip surface and having a shape that can be accommodated in a cylinder; and after forming the diamond protrusion, an n-type or p-type dopant And a step of forming an epitaxial film containing a diamond crystal containing bismuth by a plasma CVD method. As described above, the electron-emitting device of the present invention has a structure in which an epitaxial film including a diamond crystal is formed on the diamond protrusion, so that electron emission at a relatively low temperature is possible due to a relatively low work function of diamond. It becomes.

  According to the present invention, an electron-emitting device capable of emitting electrons even under a relatively low temperature and a low extraction voltage, and a method for manufacturing the electron-emitting device can be provided.

It is a figure which shows the cross-sectional structure of the electron emission element which concerns on embodiment. It is a figure which shows the variation of the diamond protrusion part which concerns on embodiment. It is a figure for demonstrating the manufacturing method of the electron emission element which concerns on embodiment. It is a picked-up image of the diamond projection part concerning an embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the description of the drawings, if possible, the same elements are denoted by the same reference numerals, and redundant description is omitted. The numerical values shown below include a predetermined error. FIG. 1 shows a cross-sectional configuration of an electron-emitting device 2 according to the embodiment. The electron-emitting device 2 includes a base portion 4, a diamond protrusion portion 5, an epitaxial film 6, and a metal film 7.

  The base part 4 and the diamond protrusion part 5 are integrally formed. The base part 4 and the diamond protrusion part 5 are all made of any one of the Ib type, IIa type and IIb type diamond crystals, but the base part 4 and the diamond protrusion part 5 are made of the same material. . In this case, the base portion 4 includes at least one type of diamond crystal of Ib type, IIa type, and IIb type, but the diamond crystal in the portion connected to the diamond protrusion portion 5 is the same as the diamond protrusion portion 5. It is a diamond crystal of the same type (type Ib, type IIa or type IIb). When an epitaxial film 6 to be described later is formed on the surface of the base portion 4 (and also the diamond protrusion portion 5) to a thickness of several μm, the diamond has high hardness, the epitaxial film 6, the base portion 4 and the diamond protrusion portion 5 Further, due to the difference in the thermal expansion coefficients of the film, the lattice constant is shifted between the epitaxial film 6 and the base part 4 and the diamond protrusion part 5, etc., strain is generated in the epitaxial film 6. Cracks may occur. However, when the base part 4 and the diamond protrusion part 5 are Ib type, IIa type, or IIb type diamond crystals, such cracks are reduced, and a high-quality epitaxial film 6 can be formed. Note that the base portion 4 may have a heteroepitaxial structure. This heteroepitaxial structure is a structure in which a diamond crystal is formed by, for example, a silicon (100) plane, a platinum (111) plane, an Ir (100) plane, or a SiC (100) plane by epitaxial growth.

  The diamond protrusion 5 has a shape that can be accommodated in a cylinder having a bottom surface with a diameter of 100 μm and a height of 1000 μm. However, when the electron-emitting device 2 is used as an electron gun chip, sufficient electric field concentration is realized. Therefore, a shape having a height of 10 to 400 μm and a thickness of 5 to 100 μm (the maximum value of the diameter of a cross section perpendicular to the height direction, the same applies hereinafter) is preferable. As long as the diamond protrusion 5 is accommodated in the cylinder and has a long and narrow shape, any shape of a cone (or a truncated cone), a cylinder, a pyramid (or a truncated pyramid), a prism, etc. It may be. For example, the diamond protrusion 5a shown in FIG. 2A, the diamond protrusion 5b shown in FIG. 2B, the diamond protrusion 5c shown in FIG. 2C, the diamond protrusion 5d shown in FIG. It may be.

  The diamond protrusion 5a has a conical shape or a truncated cone shape. The frustoconical end surface (the tip surface of the diamond protrusion 5a) may be flat or may have the same shape as a part of a virtual spherical surface. A diamond film 6a is formed on the surface (entire surface or part) of the diamond protrusion 5a. The diamond protrusion 5b has a cylindrical shape. The front end surface of the diamond protrusion 5b is flat, but may have the same shape as a part of a virtual spherical surface. A diamond film 6b is formed on the surface (entire surface or part) of the diamond protrusion 5b. The diamond projection 5c has a shape in which a cone or a truncated cone is joined to a cylinder (that is, the shape of the end of the diamond projection 5c is a cone or a truncated cone). The cone or truncated cone is provided on the end face of the cylinder, and the end face of the cylinder and the bottom face of the cone or truncated cone (in the case of the truncated cone, the larger end face of the two end faces) have the same shape. is there. The end surface of the truncated cone (tip surface of the diamond protrusion 5c) may be flat or may have the same shape as a part of a virtual spherical surface. A diamond film 6c is formed on the surface (entire surface or part) of the diamond protrusion 5c. The diamond protrusion 5d has a shape whose end is tapered stepwise. The front end surface of the diamond protrusion 5d is the frontmost surface of the stepped shape. The tip surface of the diamond protrusion 5d may be flat or may have the same shape as a part of a virtual spherical surface. A diamond film 6d is formed on the surface (entire surface or part) of the diamond protrusion 5d. The tip surfaces of the diamond protrusions 5 such as the diamond protrusions 5a to 5d described above can be accommodated in a square region having a side of 1 μm. The side surfaces of the diamond protrusion 5 such as the diamond protrusion 5 a to the diamond protrusion 5 d are larger than the area of the tip surface of the diamond protrusion 5.

  The epitaxial film 6 is formed on the surface (entire surface or part) of the base portion 4 and the diamond protrusion 5 and covers the surfaces of the base portion 4 and the diamond protrusion 5. The epitaxial film 6 may be formed only on the surface of the end of the diamond protrusion 5 (including the tip surface of the diamond protrusion 5), or the surface of the end of the diamond protrusion 5 Further, it may be formed only on a portion of the surface of the base portion 4 where the metal film 7 is formed. Further, the epitaxial film 6 may not be formed on the tip surface of the diamond protrusion 5.

  The epitaxial film 6 needs to have a relatively low activation energy in order to activate more carriers. P-doped diamond crystal is suitable for the epitaxial film 6 because the activation energy is relatively low, about 0.60 eV. N-doped diamond crystal is also suitable for the epitaxial film 6 because its activation energy is about 1.7 eV, which is relatively low. S-doped diamond crystals are also suitable for the epitaxial film 6 because the activation energy is relatively low, about 0.30 to 0.40 eV. Li-doped diamond crystals are also suitable for the epitaxial film 6 because the activation energy is 0.10 eV, which is relatively low.

Therefore, the epitaxial film 6 may contain an n-type dopant containing one or more elements of Li (lithium), P (phosphorus), S (sulfur), and N (nitrogen), and B (boron). A p-type dopant containing the element of) may be contained. When the epitaxial film 6 contains an n-type dopant, the concentration of the n-type dopant is 1 × 10 ¹³ to 1 × 10 ²² cm ⁻³ , and the activation energy of the epitaxial film 6 in this case is 0.10. -4.0 eV. When the epitaxial film 6 contains a p-type dopant, the concentration of this p-type dopant is 1 × 10 ¹³ to 1 × 10 ²² cm ⁻³ , and the activation energy of the epitaxial film 6 in this case is 0.30. ~ 2.0 eV.

  The epitaxial film 6 may include a first layer and a second layer (not shown). The first layer contains an n-type dopant containing one or more elements of Li, P, S, and N, and the second layer contains a p-type dopant containing an element of B. In this case, the first layer is formed on the surface of the end of the diamond protrusion 5 including the tip surface of the diamond protrusion 5, and the second layer is formed on the first layer, Or a 2nd layer is formed on the surface of the edge part of the diamond projection part 5 including the front end surface of the diamond projection part 5, and a 1st layer is formed on this 2nd layer. An undoped epitaxial film 6 can also be used.

  Further, the plane orientation of the region included in the surface of the base portion 4 and the diamond protrusion portion 5 where the epitaxial film 6 is formed is preferably a (111) plane on which the P-doped diamond film is most likely to grow. , (001) plane or (112) plane. Actually, the inventor has been able to uniformly form a P-doped diamond film grown on the planes of these plane orientations, and that the epitaxial film 6 having a thickness of 5 μm or more has an end portion of the diamond protrusion 5. It was confirmed that the coating could be applied.

  The metal film 7 is suitable to be capable of high adhesion, high temperature resistance and ohmic contact with the diamond crystal, and is made of, for example, Ti / W (titanium / tungsten). This Ti layer is bonded to the epitaxial film 6 or the base portion 4. A metal layer other than W may be provided on the Ti layer. Ti is a metal that can make relatively good electrical contact with diamond, and the electron injection efficiency between metal and semiconductor is considered to be the best, but it is not limited to Ti and is well known as an ohmic electrode in diamond Metals known in the art can be used. The electrode P is connected to the metal film 7.

  Hereinafter, a method for manufacturing the electron-emitting device 2 will be described with reference to FIG. First, as shown in FIG. 3A, a diamond substrate 4a is prepared. The diamond base material 4a has a shape capable of including a cylinder having a bottom surface having a diameter of 100 μm and a height of 1000 μm (a shape larger than this cylinder), and the respective materials of the base portion 4 and the diamond protrusion 5 (Ib type, IIa type, or IIb type diamond crystal). And the base part 4 and the diamond protrusion part 5 are formed from the diamond base material 4a by the following processes. That is, the end surface 8a of the diamond base material 4a is polished to form a mesa shape as shown in FIG. As a result, the diamond base material 4a becomes the diamond base material 4b in which the end face 8a side is formed in a mesa shape (mesa shape portion 10). The diamond base material 4 b has a mesa-shaped portion 10.

  Next, a metal thin film mask 9 is formed at the central portion of the end face 8b of the mesa-shaped portion 10, and the mesa-shaped portion 10 is etched using an ICP etching apparatus (ICP: Inductively Coupled Plasma), as shown in FIG. A diamond protrusion 5 as shown is formed. The mask 9 has a size (area) that can be accommodated in a square region having a side of 1 μm. By etching the mesa-shaped portion 10, the base portion 4, the diamond protrusion portion 5, and the end surface 8 c are formed from the diamond base material 4 b. The diamond protrusion 5 is formed on the end surface 8c of the base portion 4, and has a shape extending above the end surface 8c. The diamond protrusion 5 has a flat front end surface that can be accommodated in a square region having a side of 1 μm, and a side surface having an area larger than the area of the front end surface, and has a bottom surface with a diameter of 100 μm and a height of 1000 μm. It has a shape that can be accommodated in a cylinder having The surface orientation of the surface of the base portion 4 including the end face 8c and the surface of the diamond protrusion 5 is (111), (112) or (100).

  Thereafter, as shown in FIG. 3D, an epitaxial film 6 made of a diamond crystal is formed on the surfaces of the base portion 4 and the diamond protrusion portion 5 by using a plasma CVD method. Before using the plasma CVD method, the surfaces of the base portion 4 and the diamond protrusion 5 are exposed to hydrogen plasma. Thereby, the surface of the base part 4 and the diamond projection part 5 can be prepared normally and flatly. In the process of forming the epitaxial film 6 using the plasma CVD method, in order to avoid abnormal growth or etching due to plasma concentration, the diamond protrusion 5 is oriented in the direction of the electric field generated between the two electrodes that generate plasma. In other words, in other words, the plasma CVD method is used in a state where the axis of the diamond protrusion 5 is substantially perpendicular to the direction of the electric field. In this case, plasma wrap-around occurs, and epitaxial growth is possible at all 360 ° off angles, and an equivalent epitaxial film 6 is formed. When the epitaxial film 6 is P-doped, the (111) plane (or (001) plane) of the faces of the diamond projections 5 facing the electrode is preferred. ) Surface is preferred. After the epitaxial film 6 is formed, the surface of the epitaxial film 6 is formed by using one or more processing methods of FIB (Focused Ion Beam), RIE (Reactive Ion Etching), and ICP. Shape it flat. This shaping process can be performed even after the metal film 7 is formed on the entire epitaxial film 6.

  The epitaxial film 6 contains an n-type dopant (a dopant containing one or more elements of Li, P, S, and N) or a p-type dopant (a dopant containing an element of B). The epitaxial film 6 is not limited to this, and may include a first layer containing an n-type dopant and a second layer containing a p-type dopant. In this case, the first layer is formed on the surface of the end of the diamond protrusion 5 including the tip surface of the diamond protrusion 5, and the second layer is formed on the first layer, Or a 2nd layer is formed on the surface of the edge part of the diamond projection part 5 including the front end surface of the diamond projection part 5, and a 1st layer is formed on this 2nd layer.

  In addition, when the epitaxial film 6 contains the p-type dopant containing the element of B, the epitaxial film 6 (or 2nd layer) which contains this p-type dopant and is contained in the surface of the base part 4 and the diamond protrusion part 5 is included. The preferred plane orientation of the portion where is formed is (001). In addition, the thickness of the epitaxial film 6 is preferably 0.5 to 2 μm, for example, but when the first layer and the second layer are included, the thickness of each layer is preferably 1 μm or less. The epitaxial film 6 may not be formed on the tip surface of the diamond protrusion 5. Then, after the epitaxial film 6 is formed, a metal film 7 is formed on the surface of the epitaxial film 6. The metal film 7 is made of Ti / W. Through the above steps, the electron-emitting device 2 is manufactured.

  The electron-emitting device 2 having the above-described configuration can emit electrons with a relatively low extraction voltage at a relatively low temperature because the work function of the epitaxial film 6 is relatively low. Furthermore, since the epitaxial film 6 has a relatively low activation energy by containing an n-type or p-type dopant, the relatively low work function of diamond and this relatively low activation energy are sufficient. Electron emission performance can be realized.

  Further, since the electron-emitting device 2 can emit Schottky through the epitaxial film 6, the electron-emitting device 2 has good stability. That is, in addition to making it possible to make a structure that operates in each mode of thermal emission and field emission, Schottky emission by a thermal electric field can be performed. This emission mode can realize the stability of electron emission due to heat and the momentum with less variation of the emitted electrons due to field emission, that is, low energy dispersibility.

  Further, since the activation energy of the epitaxial film 6 can be controlled by selecting the doping structure of the epitaxial film 6, the stable operating temperature and voltage conditions of the epitaxial film 6 can be controlled. Thus, a doping structure suitable for each electron emission mode such as field emission, thermionic emission, or thermal field electron emission can be provided.

  Further, when the epitaxial film 6 includes the first and second layers and a pn junction is formed in the epitaxial film 6, electron emission can be controlled using a bias voltage. In addition, since the metal film 7 is provided, the electron-emitting device 2 can be used as an electron gun by applying a voltage to the metal film 7. Further, the diamond protrusion 5 has a flat tip surface that can be accommodated in a square region having a side of 1 μm and a side surface having an area larger than the area of the tip surface, and thus has an elongated shape. Further, the end of the diamond protrusion 5 including the tip surface of the diamond protrusion 5 may have a stepped shape, and thus the end of the diamond protrusion 5 can have various shapes. is there.

  A conductor coating film may be provided on the surface of the diamond protrusion 5. This conductor coating film is a metal or a good metallic conductor and covers the other surface of the diamond protrusion 5 except for the tip (electron emission portion) of the diamond protrusion 5. Such a conductor coating film is formed as follows. First, the entire diamond protrusion 5 (including the tip of the diamond protrusion 5) is covered with this conductor coating film, and then the electron emission portion is formed using a known nanoscale processing method such as FIB. The covering conductor coating film is etched to expose the diamond surface of the electron emission portion. In this manner, a conductor coating film that covers the surface of the diamond protrusion 5 excluding the electron emission portion is formed.

  Further, since the plane orientation of the region included in the surface of the diamond protrusion 5 where the epitaxial film 6 is formed is (111), (112), or (100), the epitaxial film 6 can be satisfactorily formed. Yes. Further, since the diamond protrusion 5 includes at least one type of diamond crystal of the Ib type, IIa type, and IIb type, an epitaxial film containing an n-type dopant in the case of such a crystal structure of the diamond protrusion 5. 6 can be formed on the surface of the diamond protrusion 5. The electron-emitting device 2 further includes a base 4 integrated with the diamond protrusion 5, and the diamond protrusion 5 is formed at one end of the base 4. It becomes easy to move.

  Next, a specific method for manufacturing the electron-emitting device 2 according to Example 1 will be described. The electron-emitting device 2 according to Example 1 was manufactured assuming that it is used for an electron gun. The diamond base material 4a was used as a base material containing IIb type diamond crystal, and an ICP etching apparatus was used to produce a diamond protrusion 5 having a height of 30 μm and a thickness of 6 μm as an electron gun needle. In this case, the surface orientation of the side surfaces of the base portion 4 and the diamond projection portion 5 is (111), and the epitaxial film 6 is formed on this surface by plasma CVD. The epitaxial film 6 was doped with P. A SEM photograph of the electron-emitting device 2 of Example 1 is shown in FIG. It can be seen from the crystal plane that the epitaxial film 6 is formed on the entire diamond protrusion 5. The diamond protrusion 5 and the epitaxial film 6 were shaped into a desired electron emission portion shape of the electron gun chip.

Next, a specific method for manufacturing the electron-emitting device 2 according to Example 2 will be described. The electron-emitting device 2 according to Example 2 was manufactured assuming use in an electron gun. The diamond base material 4a was used as a base material containing IIb type diamond crystal, and an ICP etching apparatus was used to produce a diamond protrusion 5 having a height of 30 μm and a thickness of 6 μm as an electron gun needle. In this case, the surface orientation of the side surfaces of the base portion 4 and the diamond projection portion 5 is (111), and H ₂ gas, CH ₄ is applied to this surface by plasma CVD method at 870 degrees Celsius and 300 W (watts). Gas and PH ₃ gas were introduced, and an epitaxial film 6 having a thickness of 2 μm was formed over 5 hours. At least the entire diamond protrusion 5 was coated with the epitaxial film 6. The epitaxial film 6 was doped with P. The diamond protrusion 5 and the epitaxial film 6 were shaped into a desired electron emission portion shape of the electron gun chip. An emission current of 100 μA was obtained from the electron gun chip of Example 2 at 1000 degrees Celsius and an extraction voltage of 3.5 kV.

Next, a specific method for manufacturing the electron-emitting device 2 according to Example 3 will be described. The electron-emitting device 2 according to Example 3 was manufactured assuming that it is used for an electron gun. The diamond base material 4a was used as a base material containing IIb type diamond crystals, and a diamond protrusion 5 having a height of 50 μm and a thickness of 8 μm was prepared as an electron gun needle using an ICP etching apparatus. In this case, the surface orientation of the side surfaces of the base portion 4 and the diamond projection portion 5 is (111), and H ₂ gas, CH ₄ is applied to this surface by plasma CVD method at 870 degrees Celsius and 300 W (watts). Gas and PH ₃ gas were introduced, and an epitaxial film 6 having a thickness of 2 μm was formed over 5 hours. At least the entire diamond protrusion 5 was coated with the epitaxial film 6. The epitaxial film 6 was doped with P. The diamond protrusion 5 and the epitaxial film 6 were shaped into a desired electron emission portion shape of the electron gun chip. An emission current of 150 μA was obtained from the electron gun chip of Example 3 at 1000 degrees Celsius and an extraction voltage of 3.5 kV.

Next, a specific method for manufacturing the electron-emitting device 2 according to Example 4 will be described. The electron-emitting device 2 according to Example 4 was manufactured assuming use in an electron gun. The diamond substrate 4a was used as a substrate containing an Ib type diamond crystal, and a diamond protrusion 5 having a height of 30 μm and a thickness of 6 μm was produced as an electron gun needle using an ICP etching apparatus. In this case, the surface orientation of the side surfaces of the base portion 4 and the diamond projection portion 5 is (111), and H ₂ gas, CH ₄ is applied to this surface by plasma CVD method at 870 degrees Celsius and 300 W (watts). Gas and PH ₃ gas were introduced, and an epitaxial film 6 having a thickness of 2 μm was formed over 5 hours. At least the entire diamond protrusion 5 was coated with the epitaxial film 6. The epitaxial film 6 was doped with P. The diamond protrusion 5 and the epitaxial film 6 were shaped into a desired electron emission portion shape of the electron gun chip. An emission current of 100 μA was obtained from the electron gun chip of Example 4 at 1000 degrees Celsius and an extraction voltage of 3.5 kV.

Next, a specific method for manufacturing the electron-emitting device 2 according to Example 5 will be described. The electron-emitting device 2 according to Example 5 was manufactured assuming use in an electron gun. The diamond base material 4a was used as a base material containing IIb type diamond crystals, and a diamond protrusion 5 having a height of 50 μm and a thickness of 8 μm was prepared as an electron gun needle using an ICP etching apparatus. In this case, the surface orientation of the side surfaces of the base portion 4 and the diamond projection portion 5 is (111), and H ₂ gas, CH ₄ is applied to this surface by plasma CVD method at 870 degrees Celsius and 300 W (watts). Gas and PH ₃ gas were introduced, and an epitaxial film 6 having a thickness of 2 μm was formed over 5 hours. At least the entire diamond protrusion 5 was coated with the epitaxial film 6. The epitaxial film 6 was doped with P. The diamond protrusion 5 and the epitaxial film 6 were shaped into a desired electron emission portion shape of the electron gun chip. An emission current of 150 μA was obtained from the electron gun chip of Example 5 at 1000 degrees Celsius and an extraction voltage of 3.5 kV.

  While the principles of the invention have been illustrated and described in the preferred embodiments, it will be appreciated by those skilled in the art that the invention can be modified in arrangement and detail without departing from such principles. The present invention is not limited to the specific configuration disclosed in the present embodiment. We therefore claim all modifications and changes that come within the scope and spirit of the following claims.

  DESCRIPTION OF SYMBOLS 10 ... Mesa shape part, 2 ... Electron emission element, 4 ... Base part, 4a, 4b ... Diamond base material, 5, 5a, 5b, 5c, 5d ... Diamond projection part, 6 ... Epitaxial film, 6a, 6b, 6c, 6d ... Diamond film, 7 ... Metal film, 8a, 8b, 8c ... End face, 9 ... Mask, P ... Electrode

Claims (12)

An electron-emitting device comprising an epitaxial film including a diamond crystal and a diamond protrusion having a surface including a region where the epitaxial film is formed,
The diamond protrusion has a shape that can be accommodated in a cylinder having a bottom surface with a diameter of 100 μm and a height of 1000 μm. A metal film provided on the epitaxial film;
The electron-emitting device according to claim 1, wherein the metal film is bonded to the epitaxial film. The epitaxial film contains an n-type dopant including one or more elements of Li, P, S, and N,
The concentration of the n-type dopant in the epitaxial film is 1 × 10 ¹³ to 1 × 10 ²² cm ⁻³ ,
The electron-emitting device according to claim 1, wherein the activation energy of the epitaxial film is 0.10 to 4.0 eV. The epitaxial film contains a p-type dopant containing an element of B,
The concentration of the p-type dopant in the epitaxial film is 1 × 10 ¹³ to 1 × 10 ²² cm ⁻³ ,
The electron-emitting device according to claim 1, wherein the activation energy of the epitaxial film is 0.30 to 2.0 eV. The epitaxial film includes a first layer and a second layer,
The first layer contains an n-type dopant including one or more elements of Li, P, S, and N,
The second layer contains a p-type dopant containing an element of B,
The first layer is formed on the surface of the end of the diamond protrusion including the tip surface, and the second layer is formed on the first layer, or the tip surface is The second layer is formed on a surface of an end portion of the diamond protrusion including the first protrusion, and the first layer is formed on the second layer. 3. The electron-emitting device according to 2.   The said diamond projection part has the flat front end surface which can be accommodated in the square area | region of 1 micrometer on one side, and the side surface of an area larger than the area of the said front end surface. The electron-emitting device according to any one of 5.   7. The electron-emitting device according to claim 1, wherein an end of the diamond protrusion including the tip surface has a stepped shape.   8. The surface orientation of a region included in the surface of the diamond protrusion and where the epitaxial film is formed is (111), (112), or (100). An electron-emitting device according to claim 1.   9. The electron-emitting device according to claim 1, wherein the diamond protrusion includes at least one type of diamond crystal of type Ib, IIa, and IIb. Further comprising a base portion integral with the diamond protrusion,
The electron-emitting device according to any one of claims 1 to 9, wherein the diamond protrusion is formed at one end of the base portion.   The electron-emitting device according to any one of claims 1 to 10, wherein the base portion has a heteroepitaxial structure. Polishing one end of a diamond substrate having a shape capable of including a cylinder having a bottom surface with a diameter of 100 μm and a height of 1000 μm and containing any one of diamond crystals of type Ib, IIa or IIb A process of forming a mesa shape;
By etching the end of the diamond base material having a mesa shape, a flat front end surface that can be accommodated in a square region having a side of 1 μm and a side surface having an area larger than the area of the front end surface Forming a diamond protrusion having a shape that can be accommodated in the cylinder; and
A step of forming an epitaxial film including a diamond crystal containing an n-type or p-type dopant by a plasma CVD method after forming the diamond protrusion;
A method for producing an electron-emitting device, comprising: