Electron source

Abstract

To provide an electron source that can improve performance.SOLUTION: According to an embodiment, an electron source 110 includes a first member 30. The first member includes a first region 31 including InxAlyGa1-x-yN (0≤x≤1, 0≤y≤1, x+y≤1) and a second region 32 including diamond including boron. In one example, the first member is irradiated with light, causing electrons to be emitted from the second region. This allows electrons to be supplied from the first region to the second region with relatively low energy (e.g., light), resulting in highly efficient electron emission.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to an electron source. [Background technology]

[0002] For example, electrons emitted from an electron source are used in electronic devices such as electron writing devices, and improvements in the characteristics of the electron source are desired. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3762535 Summary of the Invention [Problem to be solved by the invention]

[0004] Embodiments of the present invention provide an electron source with improved performance. [Means for solving the problem]

[0005] According to an embodiment of the present invention, an electron source includes a first member. The first member is made of In x Al y Ga 1-x-y The diamond includes a first region including N (0≦x≦1, 0≦y≦1, x+y≦1) and a second region including diamond including boron. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating the electron source according to the first embodiment. [Figure 2] FIG. 2 is a schematic view illustrating the electron source according to the first embodiment. [Figure 3] FIG. 3 is a schematic cross-sectional view illustrating the electron source according to the first embodiment. [Figure 4] FIG. 4 is an electron microscope photograph illustrating the electron source according to the first embodiment. [Figure 5] FIG. 5 is a schematic view illustrating the electron source according to the first embodiment. [Figure 6] FIG. 6 is a graph illustrating an electron source. [Figure 7] FIG. 7 is a graph illustrating an electron source. [Figure 8] 8A and 8B are schematic views illustrating the electron source according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In this specification and in each drawing, elements similar to those previously described with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions thereof will be omitted where appropriate.

[0008] (First embodiment)

[0009] FIG. 1 is a schematic cross-sectional view illustrating the electron source according to the first embodiment. 1, an electron source 110 according to the embodiment includes a first member 30. The first member 30 includes a first region 31 and a second region 32.

[0010] The direction from the first region 31 to the second region 32 is defined as the first direction D1. The first direction D1 is defined as the Z-axis direction. A direction perpendicular to the Z-axis direction is defined as the X-axis direction (e.g., the second direction D2). A direction perpendicular to the Z-axis direction and the X-axis direction is defined as the Y-axis direction (e.g., the third direction D3).

[0011] The first region 31 is, for example, a layer (or film) along the XY plane. The second region 32 does not have to be a homogeneous film. As will be described later, the second region 32 may be island-shaped or mesh-shaped.

[0012] The first region 31 includes a nitride. The first region 31 includes, for example, a nitride containing Ga. The first region 31 includes, for example, In x Al y Ga 1-x-y N (0≦x≦1, 0≦y≦1, x+y≦1). The first region 31 may include, for example, AlGaN or InGaN.

[0013] The second region 32 includes diamond, which may include boron.

[0014] In one example, when the first member 30 is irradiated with light (for example, at least one of the first light L1 and the second light L2), electrons are emitted from the second region 32. The second region 32 is an electron emission region.

[0015] When light is incident on the first region 31, mobile electrons are generated in the first region 31. These electrons move to the second region 32 and are emitted from the surface of the second region 32 to the outside. The first region 31 is a light absorbing region. The first region 31 supports, for example, the emission of electrons from the second region 32.

[0016] For example, there is a reference example that includes a silicon carbide film and a diamond film. In this reference example, electrons pass through the diamond film by tunneling. To achieve the tunneling effect, high energy (high electric field strength) is required, which is not practical.

[0017] In the embodiment, a first region 31 made of nitride and a second region 32 made of diamond are combined. This allows electrons to be supplied from the first region 31 to the second region 32 with relatively low energy (for example, light). This allows for highly efficient electron emission. The embodiment provides an electron source with improved characteristics.

[0018] For example, the second region 32 may contain boron, which makes the second region 32 p-type, thereby achieving higher efficiency. In an embodiment, the second region 32 may contain nitrogen.

[0019] FIG. 2 is a schematic view illustrating the electron source according to the first embodiment. 2 illustrates the energy in the first member 30. As shown in FIG. 2, the first region 31 has a first conduction band energy Ec1 of the first conduction band and a first valence band energy Ev1 of the first valence band. The difference between the first conduction band energy Ec1 and the first valence band energy Ev1 corresponds to the first bandgap energy Eg1 of the first region 31. The second region 32 has a second conduction band energy Ec2 of the second conduction band and a second valence band energy Ev2 of the second valence band. The difference between the second conduction band energy Ec2 and the second valence band energy Ev2 corresponds to the second bandgap energy Eg2 of the second region 32. The first region 31 is in contact with the second region 32, and the Fermi level Ef in the first region 31 is the same as the Fermi level in the second region 32.

[0020] For example, when the first light L1 is incident on the first region 31, mobile carriers (electrons 81 and holes 82) are generated in the first region 31. The electrons 81 are excited by the first light L1 and attempt to move to the second region 32. When the work function of the first region 31 is greater than the work function of the second region 32, a local energy valley Ed is formed between the first region 31 and the second region 32. The electrons 81 gather in the valley Ed. Furthermore, when the first member 30 is irradiated with the second light L2, the electrons gathered in the valley Ed can move to the second region 32 over the barrier between the first region 31 and the second region 32. The electrons 81 that have moved to the second region 32 are emitted to the outside. For example, the electrons 81 are emitted toward the space at the vacuum level VL.

[0021] Thus, higher efficiency is obtained when the second region 32 contains boron. This is thought to be due to the formation of a local energy valley Ed between the first region 31 and the second region 32. For example, higher efficiency is obtained by using a p-type second region 32.

[0022] The first light L1 has a first peak wavelength. The second light L2 has a second peak wavelength. The second peak wavelength is different from the first peak wavelength. For example, the first energy hv1 of the first light L1 is greater than the first band gap energy Eg1. For example, the second energy hv2 of the second light L2 is greater than the absolute value of the difference between the first conduction band energy Ec1 and the second conduction band energy Ec2.

[0023] In this embodiment, the concentration of boron in the second region 32 is, for example, 1×10 16 cm -3 That's it, 1×10 22 cm -3 The following is sufficient. Stable p-type characteristics can be obtained.

[0024] In the embodiment, the first region 31 may contain boron. For example, a portion of the boron introduced into the second region 32 may move to the first region 31 by diffusion or the like.

[0025] In the embodiment, the first region 31 may contain magnesium (Mg). The first region 31 is, for example, p-type. For example, the energy of the valence band is close to the Fermi level Ef, and the energy distribution illustrated in FIG. 2 is effectively formed. Highly efficient electron emission is obtained. In the embodiment, the concentration of Mg in the first region 31 is, for example, 1×10 16 cm -3 That's it, 1×10 22 cm -3 The following is fine.

[0026] In an embodiment, the first region 31 may include at least one selected from the group consisting of boron and magnesium.

[0027] 2, the first bandgap energy Eg1 of the first region 31 may be smaller than the second bandgap energy Eg2 of the second region 32. Carriers in the first region 31 can be excited by the first light L1 having a relatively low energy.

[0028] The second region 32 may be in contact with the first region 31. As shown in FIG. 1, the second thickness t2 of the second region 32 may be thinner than the first thickness t1 of the first region 31. This results in higher electron emission efficiency. In one example, the second thickness t2 is less than 1000 nm. The first thickness t1 is 10 nm or more and 1000 nm or less. For example, the second thickness t2 may be less than 10 nm. The first thickness t1 may be 10 nm or more and 100 nm or less. As will be described later, the second region 32 may be island-shaped or mesh-shaped. In this case, the second thickness t2 may be the average thickness.

[0029] In an embodiment, at least a portion of the second region 32 may contain hydrogen. For example, the surface of the second region 32 may be hydrogen-terminated. This may result in more stable properties.

[0030] 1, for example, the second region 32 may include a surface region 32a and a non-surface region 32b. The non-surface region 32b is provided between the first region 31 and the surface region 32a. The surface region 32a contains carbon and hydrogen. The non-surface region 32b does not contain hydrogen. Alternatively, the concentration of hydrogen in the non-surface region 32b is lower than the concentration of hydrogen in the surface region 32a.

[0031] As shown in FIG. 1 , the first member 30 may further include a third region 33. The first region 31 is provided between the third region 33 and the second region 32. The third region 33 includes, for example, Al and N. The third region 33 may further include Ga. The Al composition ratio in the third region 33 may be higher than the Al composition ratio in the first region 31. By providing the third region 33, for example, the lattice constant mismatch with the substrate (e.g., sapphire) is alleviated. For example, high crystallinity is easily obtained in the first region 31. For example, the electron affinity of the third region 33 may be greater than the electron affinity of the first region 31. For example, electrons are more easily transported from the first region 31 to the second region 32.

[0032] The electron source 110 may include at least one of a first light-emitting unit 10 and a second light-emitting unit 20, in addition to the first member 30. The first light-emitting unit 10 is configured to emit first light L1 into the first member 30. The second light-emitting unit 20 is configured to emit second light L2 into the first member 30.

[0033] In this embodiment, the dose of boron in the second region 32 is 1×10 18 cm -2 The dose of boron in the first region 31 may be less than 1×10 18 cm -2 The dose of Mg in the first region 31 may be less than 1×10 10 cm -2 That's it, 1×10 18 cm -2 The following is fine.

[0034] FIG. 3 is a schematic cross-sectional view illustrating the electron source according to the first embodiment. FIG. 4 is an electron microscope photograph illustrating the electron source according to the first embodiment. 3, in the electron source 111 according to the embodiment, the second regions 32 are island-shaped or mesh-shaped. Except for this, the configuration of the electron source 111 may be the same as the configuration of the electron source 110.

[0035] In the electron source 111, the island-like or mesh-like second region 32 provides a large surface area in the second region 32, resulting in higher electron emission efficiency. For example, part of the first region 31 is not covered with the second region 32. For example, the second region 32 is provided on part of the first region 31.

[0036] 4, the second region 32 is island-shaped. A plurality of independent island-shaped regions are provided. In an embodiment, at least a portion of the second region 32 may be a continuous region including holes. The side surfaces of the holes provide a large surface area.

[0037] FIG. 5 is a schematic view illustrating the electron source according to the first embodiment. 5 illustrates the energy when the first region 31 is not in contact with the second region 32. The first region 31 has a first conduction band energy Ec1 of the first conduction band and a first valence band energy Ev1 of the first valence band. The difference between the first conduction band energy Ec1 and the first valence band energy Ev1 corresponds to the first bandgap energy Eg1 of the first region 31.

[0038] The second region 32 has a second conduction band energy Ec2 of the second conduction band and a second valence band energy Ev2 of the second valence band. The difference between the second conduction band energy Ec2 and the second valence band energy Ev2 corresponds to a second bandgap energy Eg2 of the second region 32.

[0039] The first conduction band energy Ec1 is lower than the second conduction band energy Ec2, and a first difference between the first conduction band energy Ec1 and the second conduction band energy Ec2 corresponds to the energy difference ΔEc.

[0040] The difference between the vacuum level VL and the first conduction band energy Ec1 is defined as the first energy difference χ1. The difference between the vacuum level VL and the second conduction band energy Ec2 is defined as the second energy difference χ2. The first energy difference χ1 is larger than the second energy difference χ2. The difference between the first energy difference χ1 and the second energy difference χ2 corresponds to the energy difference ΔEc.

[0041] In the embodiment, the first bandgap energy Eg1 is smaller than the second bandgap energy Eg2. Electrons 81 are excited by the first region 31 by the first energy hv1 of the first light L1.

[0042] For example, in the embodiment, the sum (χ1+Eg1) of the first energy difference χ1 between the vacuum level VL and the first conduction band energy Ec1 of the first region 31 and the first band gap energy Eg1 is defined as the first sum. The sum (χ2+Eg2) of the second energy difference χ2 between the vacuum level VL and the second conduction band energy Ec2 of the second region 32 and the second band gap energy Eg2 is defined as the second sum. In the embodiment, the first sum (χ1+Eg1) is preferably greater than the second sum (χ2+Eg2). For example, the first valence band energy Ev1 of the first region 31 is lower than the second valence band energy Ev2 of the second region 32. This results in the band structure described with reference to FIG. 2 being obtained when the first region 31 is in contact with the second region 32.

[0043] For example, the absolute value of the first difference (energy difference ΔEc) between the first conduction band energy Ec1 and the second conduction band energy Ec2 is smaller than the first band gap energy Eg1. For example, the second energy hν2 of the second light L2 allows the electrons 81 to move from the first region 31 to the second region 32 over the barrier of the first difference (energy difference ΔEc). The second energy hν2 of the second light L2 may be smaller than the first band gap energy Eg1.

[0044] As described above, the first energy hv1 of the first light L1 is greater than the first band gap energy Eg1. The second energy hv2 of the second light L2 is greater than the absolute value of the first difference (energy difference ΔEc). The first energy hv1 is greater than the second energy hv2. By using two lights with different energies, electrons can be emitted from the first member 30 with high efficiency.

[0045] FIG. 6 is a graph illustrating an electron source. FIG. 6 shows a first region 31 made of Al y1 Ga 1-y1 The diagram illustrates various energies when the composition ratio y1 is changed in the case where N (0≦y1≦1) is included. The second region 32 is a diamond containing boron. FIG. 6 illustrates the first band gap energy Eg1, the difference (Eg2−Eg1) between the second band gap energy Eg2 and the first band gap energy Eg1, and the difference (χ1−χ2) between the first energy difference χ1 and the second energy difference χ2. For example, the diagram illustrates the value of the first energy hν1 when the first light L1 has a wavelength of 266 nm.

[0046] 6, when the composition ratio y1 is 0.54 or less, the first band gap energy Eg1 is lower than the first energy hν1. y1 Ga 1-y1 When N is contained, the first region 31 is Al y1 Ga 1-y1 It is preferable that N(0≦y1<0.54) is included.

[0047] In this example, the second energy hv2 is greater than the difference (χ1−χ2). The second energy hv2 may be less than the first bandgap energy Eg1.

[0048] FIG. 7 is a graph illustrating an electron source. FIG. 7 shows the first region 31. x1 Ga 1-x1 The diagram illustrates various energies when the composition ratio "1-x1" is changed in the case where N (0≦x1≦1) is included. The composition ratio "1-x1" is the composition ratio of Ga. The second region 32 is a diamond containing boron. FIG. 7 illustrates the first band gap energy Eg1, the difference (Eg2-Eg1) between the second band gap energy Eg2 and the first band gap energy Eg1, and the difference (χ1-χ2) between the first energy difference χ1 and the second energy difference χ2. For example, the diagram illustrates the value of the first energy hν1 when the first light L1 has a wavelength of 266 nm.

[0049] 7, when the composition ratio "1-x1" is higher than 0.9, the first band gap energy Eg1 is greater than the difference (χ1-χ2). That is, when the composition ratio x is lower than 0.1, the first band gap energy Eg1 is greater than the difference (χ1-χ2). x1 Ga 1-x1 When N is contained, the first region 31 is In x1 Ga 1-x1 The first region 31 preferably contains In x1 Ga 1-x1 N (0≦x1<0.5) may be included.

[0050] In the embodiment, for example, it is preferable that the following first formula be satisfied. 0 <Eg2-Eg1<χ1-χ2<Eg1 …(1)

[0051] In the embodiment, for example, it is preferable that the following second formula be satisfied. 0 <Eg2-Eg1<χ1-χ2<Eg1<hν1 …(2)

[0052] In the embodiment, for example, it is preferable that the following third formula be satisfied. 0 <Eg2-Eg1<χ1-χ2<hν2<Eg1<hν1 …(3)

[0053] In an embodiment, the Fermi level may be considered to be substantially the same as the valence band energy. In an embodiment, the first work function of the first region 31 may be greater than the second work function of the second region 32.

[0054] 8A and 8B are schematic views illustrating the electron source according to the first embodiment. These figures show that the first region 31 is p-type Al 0.4 Ga 0.6This corresponds to the case where the first region 31 contains N and the second region 32 contains p-type diamond. FIG. 8(a) illustrates a state where the first region 31 is not in contact with the second region 32. FIG. 8(b) illustrates a state where the first region 31 is in contact with the second region 32. As shown in FIG. 8(b), a local energy valley Ed is formed between the first region 31 and the second region 32. Highly efficient electron emission is obtained. As shown in FIG. 8(b), the vacuum level VL is lowered due to the CH dipole present on the surface of the second region 32. Highly efficient electron emission is obtained.

[0055] (Second embodiment) The second embodiment relates to an electronic device. The electronic device includes an electron source according to the first embodiment (e.g., electron source 110 or electron source 111). The electronic device may include, for example, at least one selected from the group consisting of a sensor, a switching device, an electron beam writing device, a processing device, and an analytical device. An electronic device capable of improving characteristics is provided. The sensor may include, for example, an optical sensor. The analytical device may include, for example, an electron microscope.

[0056] Information about the length and thickness can be obtained by electron microscopy, etc. Information about the composition of the material can be obtained by SIMS (Secondary Ion Mass Spectrometry) or EDX (Energy Dispersive X-ray spectroscopy), etc. Based on the information about the composition of the material, information about the energy of the material can be obtained.

[0057] The embodiments may include the following technical solutions. (Technical proposal 1) In x Al y Ga 1-x-y a first region including N (0≦x≦1, 0≦y≦1, x+y≦1); a second region comprising diamond containing boron; an electron source comprising a first member including:

[0058] (Technical proposal 2) The concentration of boron in the second region is 1×10 16 cm -3 That's it, 1×10 22 cm -3 The electron source according to Technical Solution 1 is as follows:

[0059] (Technical proposal 3) The electron source according to Technical Solution 1 or 2, wherein the first region includes at least one selected from the group consisting of boron and magnesium.

[0060] (Technical proposal 4) the first region includes magnesium; The concentration of magnesium in the first region is 1×10 16 cm -3 That's it, 1×10 22 cm -3 The electron source according to Technical Solution 3 is as follows:

[0061] (Technical proposal 5) 5. The electron source according to any one of Technical Schemes 1 to 4, wherein the second region contains nitrogen.

[0062] (Technical proposal 6) The electron source according to any one of Technical Solutions 1 to 5, wherein the second region is island-shaped or mesh-shaped.

[0063] (Technical proposal 7) 7. The electron source according to any one of Technical Solutions 1 to 6, wherein a part of the first region is not covered by the second region.

[0064] (Technical proposal 8) 8. The electron source according to any one of Technical Schemes 1 to 7, wherein at least a portion of the second region contains hydrogen.

[0065] (Technical proposal 9) the second region includes a surface region and a non-surface region; the non-surface region is provided between the first region and the surface region, the surface region comprises carbon and hydrogen; 9. The electron source according to any one of Technical Schemes 1 to 8, wherein the non-surface region does not contain hydrogen, or the concentration of hydrogen in the non-surface region is lower than the concentration of hydrogen in the surface region.

[0066] (Technical proposal 10) 10. The electron source according to any one of Technical Solutions 1 to 9, wherein the second region is in contact with the first region.

[0067] (Technical proposal 11) 11. The electron source according to any one of Technical Schemes 1 to 10, wherein the second thickness of the second region is thinner than the first thickness of the first region.

[0068] (Technical proposal 12) the second thickness of the second region is less than 1000 nm; The electron source according to any one of Technical Schemes 1 to 10, wherein the first thickness of the first region is 10 nm or more and 1000 nm or less.

[0069] (Technical proposal 13) The first region is Al y1 Ga 1-y1 The electron source according to any one of Technical Schemes 1 to 12, including N(0≦y1<0.54).

[0070] (Technical proposal 14) The first region is In x1 Ga 1-x1 The electron source according to any one of Technical Schemes 1 to 12, including N(0≦x1<0.5).

[0071] (Technical proposal 15) The electron source according to any one of Technical Solutions 1 to 14, wherein electrons are emitted from the second region when the first member is irradiated with light.

[0072] (Technical proposal 16) A first region; A second area; a first member including a first bandgap energy of the first region is smaller than a second bandgap energy of the second region; The electron source, wherein a first work function of the first region is greater than a second work function of the second region.

[0073] (Technical proposal 17) The first sum is greater than the second sum, the first sum is a sum of a first energy difference between a vacuum level and a first conduction band energy of the first region and the first band gap energy; The electron source according to Technical Solution 16, wherein the second sum is the sum of a second energy difference between the vacuum level and a second conduction band energy of the second region and the second band gap energy.

[0074] (Technical proposal 18) The electron source according to Technical Solution 17, wherein the absolute value of a first difference between the first conduction band energy and the second conduction band energy is smaller than the first band gap energy.

[0075] (Technical proposal 19) a first light emitting unit configured to emit first light having a first peak wavelength into the first member; The electron source according to Technical Solution 18, wherein the first energy of the first light is greater than the first band gap energy.

[0076] (Technical proposal 20) a second light emitting unit configured to emit second light having a second peak wavelength into the first member; The electron source according to Technical Solution 19, wherein the second energy of the second light is greater than the absolute value of the first difference.

[0077] According to the embodiment, an electron source capable of improving characteristics is provided.

[0078] The embodiments of the present invention have been described above with reference to examples. However, the present invention is not limited to these examples. For example, the specific configurations of the components and light-emitting units included in the electron source are within the scope of the present invention as long as a person skilled in the art can implement the present invention in a similar manner and obtain similar effects by appropriately selecting them from known ranges.

[0079] Any combination of two or more elements of each example within the scope of technical feasibility is also included within the scope of the present invention as long as it encompasses the gist of the present invention.

[0080] All electron sources that can be implemented by a person skilled in the art by appropriately modifying the design of the electron source described above as an embodiment of the present invention also fall within the scope of the present invention as long as they include the gist of the present invention.

[0081] Within the scope of the concept of the present invention, a person skilled in the art may conceive of various modifications and alterations, and it is understood that these modifications and alterations also fall within the scope of the present invention.

[0082] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0083] 10, 20: first and second light-emitting portions, 30: first member, 31-33: first to third regions, 32a: surface region, 32b: non-surface region, 81: electron, 82: hole, 110, 111: electron source, D1-D3: first to third directions, Ec1, Ec2: first and second conduction band energies, Ed: valley, Ef: Fermi level, Eg1, Eg2: first and second band gap energies, Ev1, Ev2: first and second valence band energies, L1, L2: first and second light, VL: vacuum level, hν1, hν2: first and second energies, t1, t2: first and second thicknesses, ΔEc: energy difference, χ1, χ2: first and second energy difference

Claims

1. In ｘ Al ｙ Ga １－ｘ－ｙ a first region including N (0≦x≦1, 0≦y≦1, x+y≦1); a second region comprising diamond containing boron; an electron source comprising a first member including:

2. 2. The electron source of claim 1, wherein the first region includes at least one selected from the group consisting of boron and magnesium.

3. The electron source of claim 1 , wherein the second region comprises nitrogen.

4. The electron source according to claim 1 , wherein the second region is in an island or mesh shape.

5. The first region is Al ｙ１ Ga １－ｙ１ N (0≦y1<0.54), or In ｘ１ Ga １－ｘ１ 5. The electron source according to claim 1, comprising N (0≦x1<0.5).

6. A first region; A second region; and a first member including: a first bandgap energy of the first region is smaller than a second bandgap energy of the second region; The electron source, wherein a first work function of the first region is greater than a second work function of the second region.

7. The first sum is greater than the second sum, the first sum is a sum of a first energy difference between a vacuum level and a first conduction band energy of the first region and the first band gap energy; 7. The electron source of claim 6, wherein the second sum is the sum of a second energy difference between the vacuum level and a second conduction band energy of the second region and the second band gap energy.

8. 8. The electron source of claim 7, wherein an absolute value of a first difference between the first conduction band energy and the second conduction band energy is less than the first band gap energy.

9. a first light emitting unit configured to emit first light having a first peak wavelength into the first member; The electron source of claim 8 , wherein the first energy of the first light is greater than the first band gap energy.

10. a second light emitting unit configured to emit second light having a second peak wavelength into the first member; The electron source of claim 9 , wherein the second energy of the second light is greater than the absolute value of the first difference.

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