JP2006080379A - Hetero crystal multilayer structure, metal paste transistor including the same, vertical cavity surface emitting laser, magnetoresistance film, and resonance tunnel diode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a multilayer structure which has layers having mutually-different crystalline structures and has an excellent crystallization. <P>SOLUTION: In the hetero crystal multilayer structure which includes two or more layers having different crystalline structures, the layers have the same bonding orbit in the crystalline structures. A multilayer structure including a compound of an NaCl structure and a compound of a CaB<SB>6</SB>structure, a multilayer structure including a metal of a body-centered cubic structure and a compound of a CsCl structure, a multilayer structure including a compound of a CaF<SB>2</SB>structure and a metal of a body-centered cubic structure, or a multilayer structure including a compound of a CaF<SB>2</SB>structure and a metal of a body-centered cubic structure is preferable. Using these multilayer structures, devices can be obtained including a metal paste transistor 1, a vertical cavity surface emitting laser, a magnetoresistance film, and a resonance tunnel diode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heterocrystalline multi-layer structure having good crystallinity, and a metal base transistor, a surface emitting laser, a magnetoresistive film, and a resonant tunnel diode using the same.

  Most of the multilayer structures are formed by alternately laminating materials having the same crystal structure. When alternately laminating materials having the same crystal structure, for example, in the most general example, when forming a multilayer structure of compound semiconductor and compound semiconductor, zinc blende structures are laminated together. (For example, refer nonpatent literature 1). Alternatively, in the case of a nitride semiconductor that has been attracting attention in recent years, a multilayer structure is formed by laminating wurtzite structures.

  When the crystal structures are different, a combination of materials having substantially the same lattice constant such as GaAs and ErAs is used (for example, see Non-Patent Document 2).

IEEE ELECTRON DEVICE LETT. 25 (2004) 58 APPL. PHYS. LETT 60 (1992) 2341

  Examples of parameters that can be changed by a combination of compound semiconductors having the same crystal structure include a band gap and a piezoelectric field in some nitride semiconductors. Other than that, there are few useful parameters that can be varied and are limited to optical applications only.

  Therefore, a laminated structure of compounds having different crystal structures has been studied aiming at new functionality. In creating a laminated structure of compounds having different crystal structures, attention is paid mainly to how much the lattice constants are matched. However, considering only the consistency of the lattice constant, the crystallinity is significantly deteriorated as the film thickness is increased, and the crystallinity of the laminated structure of the upper layer is often significantly affected. For example, in the case of a combination of GaAs and ErAs in Non-Patent Document 2, the crystallinity looks good when one of the layers is two or less molecular layers. descend. When stacking compounds having different crystal structures in this way, a multilayer structure having good crystallinity cannot be obtained only by matching lattice constants.

  So far, no combination having good crystallinity that can be used in various devices has been found.

  An object of the present invention is to realize a heterogeneous crystalline multi-layer structure composed of compounds having different crystal structures in layers and having excellent crystallinity.

  As a result of intensive studies, the present inventor has found that, with respect to a laminated structure of materials having different crystal structures, the bond orbits constituting the crystal structure have a significant effect on obtaining good crystallinity. For example, in the case of GaAs and ErAs in Non-Patent Document 2, the bond orbit of GaAs is an sp3 hybrid orbit, whereas the bond orbit of ErAs is a p orbit, so there is no matching of the bond orbits. A good multilayer structure cannot be obtained. However, when one side has two or less molecular layers, it may be forcibly stabilized by the bond orbit of the other material. For example, ErAs with two or less molecular layers is forcibly stabilized by sp3 hybrid orbital, so that the crystallinity looks good, but when it becomes ErAs with three molecular layers, the p-orbital is stabilized, so that the crystallinity of GaAs above it Is significantly reduced.

  Then, the present inventor found that a multilayer structure having excellent crystallinity can be obtained as long as the bond orbits constituting the crystal structure are the same as well as the lattice constant consistency with respect to the multilayer structure using materials having different crystal structures. It has been found that this can be realized, and furthermore, a combination of crystal structures having the same bond orbital constituting the crystal structure has been found and the present invention has been completed.

The present invention is a heterogeneous crystal multilayer structure including two or more layers having different crystal structures,
Two or more layers having different crystal structures are different crystal multilayer structures characterized in that the bond orbits constituting the crystal structure are the same.

In the present invention, two or more layers having the same bond orbital constituting the crystal structure and different crystal structures are composed of a layer made of a compound having a crystal structure of NaCl structure and a compound having a crystal structure of CaB ₆ structure. And a layer.

  In the present invention, two or more layers having the same bond orbital constituting the crystal structure and different crystal structures are composed of a layer made of a metal having a body-centered cubic structure and a compound having a CsCl structure. And a layer.

In the present invention, two or more layers having the same bond orbital constituting the crystal structure and different crystal structures are composed of a layer made of a compound having a crystal structure of CaF ₂ structure and a metal having a crystal structure of face centered cubic structure. And a layer made of

In the present invention, two or more layers having the same bond orbital constituting the crystal structure and different crystal structures are composed of a layer made of a compound having a crystal structure of CaF ₂ structure and a metal having a crystal structure of body-centered cubic structure. And a layer made of

However, it preferred 2 ^0.5 times the lattice constant of a face-centered cubic structure and CaF ₂ structure when the combination with a different body-centered cubic structure of that substantially coincides with the lattice constant of the CaF ₂ structure. That is, it is preferable that there is an epitaxial orientation relationship of <100> CaF ₂ / <110> bcc.

  The present invention is a metal base transistor comprising the heterogeneous crystal multilayer structure as an emitter layer, a collector layer, and a metal base layer.

  The present invention is a surface emitting laser comprising the heterogeneous crystal multilayer structure as a distributed Bragg reflector.

  The present invention is a magnetoresistive film comprising the heterogeneous crystal multilayer structure as a multilayer structure having a magnetoresistive effect.

  The present invention is a resonant tunneling diode comprising the heterogeneous crystal multilayer structure as a resonant tunneling structure having a resonant tunneling effect.

  According to the present invention, when a multilayer structure is manufactured by stacking two or more layers having different crystal structures, different layers having good crystallinity are formed by stacking layers having the same bond orbital constituting the crystal structure. A crystal multilayer structure can be obtained. In addition, the heterogeneous crystal multilayer structure can change not only the optical characteristics but also the electrical and magnetic characteristics such as the resistance value, so that the characteristics of the device to which the present invention is applied can be dramatically improved. Can be improved.

According to the present invention, the bond orbital constituting the NaCl structure in the compound having the NaCl structure is the p orbital, and the bond orbital constituting the CaB ₆ structure in the compound having the CaB ₆ structure is also the p orbital taken by the Ca. is there. In this CaB ₆ structure compound, B ₆ molecules are encapsulated by Ca simple lattices. Accordingly, since the bonding orbital matching is achieved between the NaCl structure compound and the CaB ₆ structure compound, it is possible to realize a heterogeneous crystal multilayer structure having excellent crystallinity. This heterogeneous crystal multilayer structure can be used for various optical / electrical devices, etc., has good crystallinity, and can combine various compounds to produce a device exhibiting excellent characteristics. Obtainable.

  According to the present invention, in a metal having a body-centered cubic structure, the bond orbits constituting the body-centered cubic structure are sp3 hybrid orbitals, and in one compound of the CsCl structure, the bond orbits constituting the CsCl structure are also sp3 hybrid orbitals. . Accordingly, since the bonding orbital consistency between both the metal having a body-centered cubic structure and the compound having a CsCl structure is obtained, it is possible to realize a heterogeneous crystal multilayer structure having excellent crystallinity. This heterogeneous crystal multilayer structure can be used for various optical / electrical devices, etc., has good crystallinity, and can combine various compounds to produce a device exhibiting excellent characteristics. Obtainable.

According to the present invention, CaF ₂ structure is a form of simple grating is encapsulated by F atoms in Ca grid of face-centered cubic structure, bonding orbitals constituting the CaF ₂ structure in the compounds of the CaF ₂ structure Is a sp3 hybrid orbital, and a bond orbit constituting a face centered cubic structure in a metal having one face centered cubic structure is also a sp3 hybrid orbital. Therefore, since the bonding orbital consistency is obtained between the CaF ₂ structure compound and the metal having the face-centered cubic structure, it is possible to realize a heterogeneous crystal multilayer structure with excellent crystallinity. This heterogeneous crystal multilayer structure can be used for various optical / electrical devices, etc., has good crystallinity, and can combine various compounds to produce a device exhibiting excellent characteristics. Obtainable.

According to the present invention, CaF ₂ structure is a form of simple grating is encapsulated by F atoms in Ca grid of face-centered cubic structure, bonding orbitals constituting the CaF ₂ structure in the compounds of the CaF ₂ structure Is a sp3 hybrid orbital, and a bond orbit constituting a body-centered cubic structure in a metal having one body-centered cubic structure is also a sp3 hybrid orbital. Accordingly, since the bonding orbital consistency is obtained between the compound having the CaF ₂ structure and the metal having the body-centered cubic structure, it is possible to realize a heterogeneous crystal multilayer structure having excellent crystallinity. This heterogeneous crystal multilayer structure can be used for various optical / electrical devices, etc., has good crystallinity, and can combine various compounds to produce a device exhibiting excellent characteristics. Obtainable.

  According to the present invention, a metal base transistor can be obtained using a heterogeneous crystal multilayer structure. This metal base transistor can have good electrical characteristics.

  According to the present invention, it is possible to obtain a surface emitting laser including a DBR (distributed Bragg reflector) having a large reflectance with a small number of layers by using a different crystal multilayer structure.

  According to the present invention, a magnetoresistive film can be obtained from a heterogeneous crystal multilayer structure. This magnetoresistive film can have a large resistance change rate.

  According to the present invention, a resonant tunneling diode including a heterogeneous crystal multilayer structure can be obtained.

  The heterogeneous crystal multilayer structure of the present invention is a multilayer structure including two or more layers made of materials having different crystal structures, and the bonding orbits constituting the crystal structure of each layer are the same.

Examples of a heterogeneous multilayer structure (hereinafter, simply referred to as “multilayer structure”) including adjacent layers that are heterogeneous crystals and have the same bond orbit constituting the crystal structure include, for example, a compound having an NaCl structure and CaB _6. A multilayer structure including a compound having a structure, a multilayer structure including a metal having a body-centered cubic structure and a compound having a CsCl structure, a multilayer structure including a compound having a CaF ₂ structure and a metal having a face-centered cubic structure, CaF Examples include a multilayer structure including a compound having a _two- structure and a metal having a body-centered cubic structure. The material for these layers is not particularly limited, but inorganic compounds can be preferably used.

[Multilayer structure including a compound having a NaCl structure and a compound having a CaB ₆ structure]
Underlying bonding orbital of the NaCl structure is p-orbital, in the case of one of the CaB ₆ structure, since the shape of the CaB ₆ is _{B 6} molecules are encapsulated by a Ca simple grating, bonding orbitals The underlying of Ca It is the p orbit taken. Since the bonding orbits are consistent between the two, for example, by stacking using epitaxial growth or the like, a heterogeneous crystal multilayer structure having good crystallinity can be obtained. This multilayer structure can be used for various optical / electrical devices, etc., has a good crystallinity, and can combine various compounds to obtain a device exhibiting excellent characteristics. Can do.

  The compound having the NaCl structure is not particularly limited, and examples thereof include rare earth element nitrides, phosphides, arsenides, antimonides, oxides, sulfides, selenides, tellurides, and magnesium oxide. Rare earth element-containing compounds having an NaCl structure have wide band gap values, and can be preferably used from the viewpoint of changing from a semiconductor to a semimetal and also becoming a magnetic semiconductor.

Examples of the compound take CaB ₆ structure is not particularly limited, for _{example, BaB 6, CaB 6, CeB} 6, DyB 6, ErB 6, GdB 6, LaB 6, LuB 6, NdB 6, PrB 6, SiB 6, SmB ₆ , SrB ₆ , TbB ₆ , ThB ₆ , TmB ₆ , YB ₆ and YbB _{6 and the} like. Rare earth element-containing hexaboride compounds having a CaB ₆ structure can be preferably used because they have a wide range of band gap values, change from a semiconductor to a semimetal, and also become a magnetic semiconductor. Furthermore, NdB ₆ and BaB ₆ can be preferably used from the viewpoint of lattice matching with other materials.

[Multilayer structure including a metal having a body-centered cubic structure and a compound having a CsCl structure]
In both cases of the body-centered cubic structure and the CsCl structure, the basic bond orbitals are sp3 hybrid orbitals, and the bond orbital consistency between them is achieved, so that a multilayer structure with excellent crystallinity is realized. Is possible.

  Although it does not restrict | limit especially as a metal which takes a body centered cubic structure, For example, Ba, Cr, Fe, Hf, Li, Tl, Eu etc. are mentioned.

  The compound having a CsCl structure is not particularly limited, and examples thereof include CsI.

  As a combination of a metal having a body-centered cubic structure and a compound having a CsCl structure, a combination of Eu and CsI can be more preferably used.

[Multilayer structure including a compound having a CaF ₂ structure and a metal having a face-centered cubic structure]
The basic structure of the CaF ₂ structure is such that a simple lattice of F atoms is included in a Ca lattice having a face-centered cubic structure. Therefore, since the basic bonding orbitals are both sp3 hybrid orbitals, the matching of the bonding orbitals is established between the two, so that a multilayer structure with excellent crystallinity can be realized.

Examples of the compound take CaF ₂ structure is not particularly limited, for example, Ba, Ca, hydrides of fluoride and rare earth elements such as Eu and the like. Rare earth element-containing compounds having a CaF ₂ structure have wide band gap values, and can be preferably used from the viewpoint of changing from a semiconductor to a semimetal and also becoming a magnetic semiconductor. CaF ₂ can also be preferably used from the viewpoint of lattice constant matching.

  The metal having a face-centered cubic structure is not particularly limited, and examples thereof include Yb, Ag, Al, Au, Co, Cr, Cu, Ni, Pd, Pt, and Rh.

[Multilayer structure including a compound having a CaF ₂ structure and a metal having a body-centered cubic structure]
The basic structure of the CaF ₂ structure is such that a simple lattice of F atoms is included in a Ca lattice having a face-centered cubic structure. Therefore, the basic bond orbital of the compound having the CaF ₂ structure is the sp3 hybrid orbital. The bond orbit of the metal having a body-centered cubic structure is sp3. From these, it is possible to realize a multilayer structure excellent in crystallinity because the bonding orbital consistency is obtained between the compound having the CaF ₂ structure and the metal having the body-centered cubic structure. However, it is necessary to 2 ^0.5 times the lattice constant of the combination of metal with different body-centered cubic structure is a compound face-centered cubic structure is a CaF ₂ structure substantially coincides with the lattice constant of the CaF ₂ structure. That is, an epitaxial orientation relationship of <100> CaF ₂ / <110> bcc is required.

Examples of the compound take CaF ₂ structure is not particularly limited, for example, Ba, Ca, hydrides of fluoride and rare earth elements such as Eu and the like. Rare earth element-containing compounds having a CaF ₂ structure have wide band gap values, and can be preferably used from the viewpoint of changing from a semiconductor to a semimetal and also becoming a magnetic semiconductor. CaF ₂ can also be preferably used from the viewpoint of lattice constant matching.

  Although it does not restrict | limit especially as a metal which takes a body centered cubic structure, For example, Ba, Cr, Fe, Hf, Li, Tl, Eu etc. are mentioned.

  Since these multi-layered structures are consistent in the bonding orbits constituting the crystal, for example, a multi-layered structure having good crystallinity can be produced by epitaxial growth and stacking.

  In these multilayer structures, the lattice constant of each layer is not particularly limited, but is preferably approximated. However, even if the lattice constants of the layers are not so approximate, it is possible to avoid mismatching of the lattice constants. FIG. 7 is a cross-sectional view showing an example of avoidance means when the lattice constants of two adjacent layers do not match. For example, even if the lattice constants of the adjacent two layers 52 and 53 are b or c, and b and c are not so approximate, the lattice constant is on the substrate 51 having the lattice constant a satisfying b <a <c. By using a method of forming the two layers 52 and 53 that are not so approximate, the lattice constants b and c of these two layers can be brought close to the lattice constant a of the substrate. By such a method, it is possible to avoid mismatching of lattice constants between two adjacent layers.

  Hereinafter, devices to which these multilayer structures are applied will be shown, but the present invention is not limited thereto.

[Metal base transistor]
FIG. 1 is a cross-sectional view schematically showing a configuration of a metal base transistor 1 according to the first embodiment. In the first embodiment, the metal base transistor 1 includes a substrate 2, a buffer layer 3, a collector layer 4, a metal base layer 5, an emitter layer 6, a collector electrode 7, a base electrode 8, and an emitter electrode 9. . For the collector layer 4, the metal base layer 5 and the emitter layer 6, for example, a multilayer structure composed of a compound having a NaCl structure and a compound having a CaB ₆ structure can be preferably used. The material of the metal base transistor 1 is not particularly limited. For example, the substrate 2 is GaAs, the buffer layer 3 is a compound VN having an NaCl structure, the collector layer 4 is an n-type VN having a NaCl structure, a metal base NdB ₆ in the layer 5 are compounds take CaB ₆ structure, the emitter layer 6 is a compound to adopt a NaCl structure n-type VN, the collector electrode 7 and the emitter electrode 9 Ti / Al (lower layer / upper layer) (hereinafter "/" In this case, Nd / Au can be preferably used for the base electrode 8. The growth method such as VN is not particularly limited, and examples include RF sputtering, molecular beam epitaxy (MBE), and metal organic chemical vapor deposition (MOCVD). Further, since the buffer layer 2 is provided for reasons such as the matching of the crystal structure and the lattice constant, it may not be provided if the crystal structure and the lattice constant are matched.

[Surface emitting laser]
FIG. 2 is a cross-sectional view schematically showing the configuration of the surface emitting laser 11 of the second embodiment. The surface emitting laser includes a substrate 12, a buffer layer 13, a lower DBR (distributed Bragg reflector) 14, an n-type carrier diffusion layer 15, a lower graded layer 16, an active layer 17, an upper graded layer 18, and a p-type carrier diffusion layer. 19, an upper DBR (distributed Bragg reflector) 20, a p-type electrode 21 and an n-type electrode 22. The lower DBR 14 and the upper DBR 20 are not particularly limited, but a multilayer structure composed of a compound having a NaCl structure and a compound having a CaB ₆ structure can be preferably used.

The surface emitting laser material is not particularly limited. For example, the substrate 12 is SmO, the buffer layer 13 is GdN, the lower DBR 14 is BaB ₆ / LaN, and the n-type carrier diffusion layer 15 includes Si as a carrier. Type GdN, lower graded layer 16 is InGdN, active layer 17 is InGdN, upper graded layer 18 is InGdN, p-type carrier diffusion layer 19 is p-type GdN containing Mg as a carrier, and upper DBR 20 has a CaB ₆ structure. A multilayer structure of BaB ₆ which is a compound to be taken and LaN which is a compound which has a NaCl structure, Ti / Al for the p-type electrode 21 and Pt / Au for the n-type electrode 22 can be preferably used. In this embodiment, since a compound containing a metal such as BaB ₆ can be used for DBR, a large reflectance can be obtained with a small number of layers.

[Magnetic resistance film]
FIG. 3 is a cross-sectional view schematically showing the magnetoresistive film 31 of the third embodiment. The magnetoresistive film 31 includes a substrate 32, a multilayer structure 33, and an electrode 34. For the multilayer structure 33, for example, a multilayer structure made of a metal having a body-centered cubic structure and a compound having a CsCl structure can be preferably used. As the material of the magnetoresistive film, the substrate 32 is CsI, the multilayer structure 33 is a layer 33a made of Eu which is a metal having a body-centered cubic structure, and layers 33b made of CsI which is a compound having a CsCl structure are alternately arranged a plurality of times. A laminated multilayer structure can be preferably used.

[Resonant tunnel diode]
FIG. 4 is a cross-sectional view schematically showing the resonant tunnel diode 41 of the fourth embodiment. The resonant tunnel diode 41 includes a substrate 42, a buffer layer 43, a resonant tunnel structure 44, and an electrode 45. The resonant tunnel structure 44 includes a multilayer structure composed of a metal having a face-centered cubic structure and a compound having a CaF ₂ structure, and a multilayer structure composed of a metal having a body-centered cubic structure and a compound having a CaF ₂ structure. It can be preferably used. As a material of the resonant tunnel diode 41, a multilayer structure in which the substrate 42 is Si, the buffer layer 43 is CaF ₂ , and the resonant tunnel structure 44 is a laminate of Yb / CaF ₂ / Yb / CaF ₂ / Yb can be preferably used. Instead of Yb which is a metal having a face-centered cubic structure, Tl which is a metal having a body-centered cubic structure can also be preferably used.

Although _CaF 2 / CdF ₂ resonant tunneling structure using only CaF ₂ structure is known, the Cd (cadmium), there is a problem in safety. On the other hand, Yb (ytterbium) and Tl (thallium) can be used satisfactorily without such problems.

  This resonant tunneling diode can be applied to high-speed electronic switches, high-frequency oscillators, functional elements, and the like.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
The metal base transistor 1 of the first embodiment was produced. On the 300 μm thick semi-insulating GaAs substrate 2, VN (vanadium nitride) was grown thick so as to alleviate the difference in crystal structure and the lattice constant, specifically, 3 μm was grown to form the VN buffer layer 3. . In this example, the VN layer was grown using an RF sputtering method capable of heating the substrate up to 1200 ° C. Next, n-type VN (carrier concentration 5 × 10 ¹⁷ cm ⁻³ ) was grown to 200 nm to form a collector layer 4. Thereafter, NdB ₆ was grown to 100 nm to form the base layer 5. Further, n-type VN was grown to 150 nm to form the emitter layer 6. For the growth of the VN layer, reactive sputtering using Ar—N ₂ was performed using a V (vanadium) target (purity 99.99%) at a substrate temperature of 1000 ° C. The growth of NdB ₆ (neodymium hexaboride) was performed by reactive sputtering using Ar—B ₂ H ₆ (diborane) using a Nd (neodymium) target (purity 99.9%) at a substrate temperature of 1000 ° C. . This was subjected to photolithography to form electrodes 7, 8, and 9 to complete a metal base transistor. The electrodes 7 and 9 were formed by forming Ti / Al (thickness 16 nm / 200 nm) and annealing at 600 ° C. for 30 seconds. The electrode 8 was made of Nd / Au (thickness 20 nm / 100 nm) without annealing. Thereafter, when the operation was confirmed, the transistor characteristics of FIG. 5 were obtained.

(Example 2)
The surface emitting laser 11 of the second embodiment was produced. As the growth method, the RF sputtering method was used as in the first embodiment. A GdN buffer layer 13 was grown 2 μm at a substrate temperature of 900 ° C. on an SmO substrate 12 having a thickness of 100 μm, and then a BaB ₆ (10 nm) / LaN (15 nm) stacked structure was grown for four periods to form a lower DBR 14. Subsequently, n-type GdN containing Si (carrier concentration 1 × 10 ¹⁸ cm ⁻³ ) is grown to a film thickness of 1 μm to form an n-type carrier diffusion layer 15, and the In composition is changed from 0 to 10 at%. InGdN is grown to 20 nm to form a lower graded layer 16, In _0.2 Gd _0.8 N is grown to 10 nm to form an active layer 17, and the In composition is changed from 10 at% to 0%. Then, the upper graded layer 18 was formed by growing the InGdN layer by 20 nm. P-type GdN containing Mg (carrier concentration 1 × 10 ¹⁸ cm ⁻³ ) is grown to 200 nm to form a p-type carrier diffusion layer 19, and a BaB ₆ (10 nm) / LaN (15 nm) stacked structure is stacked for two periods. Upper DBR 20 was formed. Thereafter, Ti / Al (thickness 16 nm / 200 nm) was grown and annealed at 600 ° C. for 30 seconds to form the p-type electrode 21. Further, Pt / Au (thickness 20 nm / 100 nm) was grown and an n-type electrode 22 was formed without annealing to produce a surface emitting laser. In a normal surface emitting laser, a semiconductor multilayer structure is used, but in the present invention, a high reflectance can be obtained with a small number of layers by using a BaB ₆ metal, and a threshold voltage of 2.5 V is applied to a 5 μm square element. The laser oscillation was confirmed at a threshold current of 450 μA.

(Example 3)
A magnetoresistive film 31 of the third embodiment was produced. In this example, growth was performed at a substrate temperature of 200 ° C. using a molecular beam epitaxy method. Eu (Europium) and CsI sealed in a pBN crucible were heated on a CsI substrate (thickness 150 μm) 32 to grow Eu (1 nm) / CsI (1 nm) multilayer structure 33 for 20 periods. An electrode 34 was prepared using Au. And the change of magnetoresistance was investigated. As a result, a 200% change in resistance was confirmed when a magnetic field of 79.58 kA / m (1 kilo-Oersted) was applied. This change in resistance, the resistivity [rho ₀ when no magnetic _field, the resistivity when a magnetic field as [rho _H, with ρ _0> ρ _H, calculating the _{(ρ 0 -ρ H) / ρ} 0 Determined by And this resistivity was measured using the usual 4 terminal method.

Example 4
The resonant tunnel diode 41 of the fourth embodiment was created. A metal / insulator / metal / insulator / metal laminate structure was used for the resonant tunneling structure. The MBE method combined with electron beam heating was used as the crystal growth method. A buffer layer 43 made of CaF _{2 is} grown on a 300 μm-thick Si substrate 42 at a substrate temperature of 300 ° C., and then Yb (100 nm) / CaF ₂ (0.5 nm) / Yb (1 nm) at the same substrate temperature. The resonant tunnel structure 44 was formed by stacking / CaF ₂ (0.5 nm) / Yb (50 nm), and finally, Au was formed to 200 nm to form an electrode 45. Electron beam (EB) heating was used for evaporation of CaF ₂ , and Yb used crucible heating.
The resonant tunnel effect shown in FIG. 6 was confirmed by passing a current between the upper and lower Yb.

(Example 5)
A resonant tunneling diode 41 was similarly fabricated using Tl instead of Yb in Example 4, and the resonant tunneling effect was confirmed.

It is sectional drawing which shows the metal base transistor of 1st Embodiment. It is sectional drawing which shows the surface emitting laser of 2nd Embodiment. It is sectional drawing which shows the magnetoresistive film of 3rd Embodiment. It is sectional drawing which shows the resonant tunnel diode of 4th Embodiment. FIG. 3 is a diagram illustrating transistor characteristics of the metal base transistor of Example 1. It is a figure which shows the resonant tunnel effect of the resonant tunnel diode of Example 4. FIG. It is sectional drawing which shows an example of the avoidance means when the lattice constant of two adjacent layers does not correspond.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal base transistor 2 Substrate 3 Buffer layer 4 Collector layer 5 Base layer 6 Emitter layer 7 Collector electrode 8 Base electrode 9 Emitter electrode 11 Surface emitting laser 12 Substrate 13 Buffer layer 14 Lower DBR
15 n-type carrier diffusion layer 16 lower graded layer 17 active layer 18 upper graded layer 19 p-type carrier diffusion layer 20 upper DBR
21 p-type electrode 22 n-type electrode 31 magnetoresistive film 32 substrate 33 multilayer structure 34 electrode 41 resonant tunnel diode 42 substrate 43 buffer layer 44 resonant tunnel structure 45 electrode

Claims (9)

A heterogeneous crystal multilayer structure including two or more layers having different crystal structures,
Two or more layers having different crystal structures have the same bond orbital constituting the crystal structure. The two or more layers having the same bond orbital constituting the crystal structure and different crystal structures include a layer made of a compound having a crystal structure of NaCl structure and a layer made of a compound having a crystal structure of CaB ₆ structure. The heterogeneous crystal multilayer structure according to claim 1.   Two or more layers having the same bond orbital and different crystal structures constituting a crystal structure include a layer made of a metal having a body-centered cubic structure and a layer made of a compound having a CsCl structure. The heterogeneous crystal multilayer structure according to claim 1, comprising: Two or more layers having the same bond orbit and different crystal structures constituting the crystal structure include a layer made of a compound having a crystal structure of CaF ₂ structure and a layer made of a metal having a crystal structure of face centered cubic structure. The heterogeneous crystal multilayer structure according to claim 1, comprising: The two or more layers having the same bond orbit and different crystal structures constituting the crystal structure include a layer made of a compound having a crystal structure of CaF ₂ structure and a layer made of a metal having a crystal structure of body-centered cubic structure. The heterogeneous crystal multilayer structure according to claim 1, comprising:   A metal base transistor comprising the heterogeneous crystal multilayer structure according to any one of claims 1 to 5 as an emitter layer, a collector layer, and a metal base layer.   A surface-emitting laser comprising the heterogeneous crystal multilayer structure according to claim 1 as a distributed Bragg reflector.   A magnetoresistive film comprising the heterogeneous crystal multilayer structure according to claim 1 as a multilayer structure having a magnetoresistive effect. A resonant tunneling diode comprising the heterogeneous crystal multilayer structure according to claim 1 as a resonant tunneling structure having a resonant tunneling effect.

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