KR20090093371A - Room-temperature ferromagnetic semiconductor and manufacturing method thereof - Google Patents
Room-temperature ferromagnetic semiconductor and manufacturing method thereofInfo
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- KR20090093371A KR20090093371A KR1020080018865A KR20080018865A KR20090093371A KR 20090093371 A KR20090093371 A KR 20090093371A KR 1020080018865 A KR1020080018865 A KR 1020080018865A KR 20080018865 A KR20080018865 A KR 20080018865A KR 20090093371 A KR20090093371 A KR 20090093371A
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- 239000004065 semiconductor Substances 0.000 title claims abstract description 51
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- 230000005294 ferromagnetic effect Effects 0.000 title claims description 45
- 239000000843 powder Substances 0.000 claims abstract description 23
- 238000005245 sintering Methods 0.000 claims abstract description 12
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims abstract description 8
- 238000002156 mixing Methods 0.000 claims abstract description 6
- 239000011812 mixed powder Substances 0.000 claims abstract description 5
- 239000000758 substrate Substances 0.000 claims abstract description 5
- YZCKVEUIGOORGS-OUBTZVSYSA-N Deuterium Chemical compound [2H] YZCKVEUIGOORGS-OUBTZVSYSA-N 0.000 claims abstract description 4
- 229910052786 argon Inorganic materials 0.000 claims abstract description 4
- 238000000034 method Methods 0.000 claims description 19
- 239000000463 material Substances 0.000 claims description 12
- 238000000151 deposition Methods 0.000 claims description 10
- 239000000126 substance Substances 0.000 claims description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 4
- 239000001301 oxygen Substances 0.000 claims description 4
- 229910052760 oxygen Inorganic materials 0.000 claims description 4
- 230000010287 polarization Effects 0.000 abstract description 3
- 239000007789 gas Substances 0.000 abstract description 2
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- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 abstract description 2
- JKQOBWVOAYFWKG-UHFFFAOYSA-N molybdenum trioxide Chemical compound O=[Mo](=O)=O JKQOBWVOAYFWKG-UHFFFAOYSA-N 0.000 abstract 2
- 230000005307 ferromagnetism Effects 0.000 abstract 1
- LEDMRZGFZIAGGB-UHFFFAOYSA-L strontium carbonate Chemical compound [Sr+2].[O-]C([O-])=O LEDMRZGFZIAGGB-UHFFFAOYSA-L 0.000 abstract 1
- 229910000018 strontium carbonate Inorganic materials 0.000 abstract 1
- 230000005291 magnetic effect Effects 0.000 description 12
- 230000008859 change Effects 0.000 description 11
- 239000010409 thin film Substances 0.000 description 9
- 230000005415 magnetization Effects 0.000 description 5
- 238000004549 pulsed laser deposition Methods 0.000 description 5
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- 230000008569 process Effects 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 229910052723 transition metal Inorganic materials 0.000 description 3
- 150000003624 transition metals Chemical class 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 230000005355 Hall effect Effects 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
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- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 238000002128 reflection high energy electron diffraction Methods 0.000 description 2
- 238000012827 research and development Methods 0.000 description 2
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- 229910000673 Indium arsenide Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000002547 anomalous effect Effects 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 238000013500 data storage Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- RPQDHPTXJYYUPQ-UHFFFAOYSA-N indium arsenide Chemical compound [In]#[As] RPQDHPTXJYYUPQ-UHFFFAOYSA-N 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
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- 239000002086 nanomaterial Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
- C01G49/02—Oxides; Hydroxides
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
- H01L21/283—Deposition of conductive or insulating materials for electrodes conducting electric current
- H01L21/285—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation
- H01L21/28506—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers
- H01L21/28512—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers on semiconductor bodies comprising elements of Group IV of the Periodic Table
- H01L21/2855—Deposition of conductive or insulating materials for electrodes conducting electric current from a gas or vapour, e.g. condensation of conductive layers on semiconductor bodies comprising elements of Group IV of the Periodic Table by physical means, e.g. sputtering, evaporation
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/324—Thermal treatment for modifying the properties of semiconductor bodies, e.g. annealing, sintering
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Abstract
Description
본 발명은 반도체 물질에 관한 것으로, 상온에서 강자성을 가지는 반도체 및 그 제조 방법에 관한 것이다.TECHNICAL FIELD The present invention relates to a semiconductor material, and more particularly to a semiconductor having ferromagnetic properties at room temperature and a method of manufacturing the same.
묽은 자성 반도체(Diluted Magnetic Semiconductor, DMS)가 전기적으로는 반도체로서의 특성을, 자성적인 면에서는 강자성 특성을 동시에 갖고 있는 것으로 알려지면서 이에 대한 연구가 활발히 진행되고 있다.Diluted Magnetic Semiconductors (DMS) are known to have electrical characteristics as semiconductors and ferromagnetic characteristics in terms of magnetic properties.
이러한 강자성 반도체는 전하가 가지는 전기적인 특성, 즉 전기적인 양(+), 음(-) 뿐만 아니라, 전자의 스핀 업, 스핀 다운이라는 두 가지 다른 자성 상태를 데이터 처리 또는 데이터 저장에 사용할 수 있게 됨으로써, 반도체의 집적도를 크게 향상시킬 수 있다는 특징이 있으며, 이를 통해 스핀트로닉스(spintronics)라는 새로운 영역이 개척되고 있다.These ferromagnetic semiconductors can be used for data processing or data storage, as well as the electrical properties of the charge, that is, electrical positive (+) and negative (-), as well as two different magnetic states: spin up and spin down of electrons. In other words, the integration of semiconductors can be greatly improved, which opens up a new area of spintronics.
종래의 강자성 반도체의 개발은 주로 GaAs, InAs의 III-V족 화합물 반도체에 전이금속인 Mn을 첨가하여 진행되고 있다. 최근에는 화합물 반도체 발광다이오드와 이종 접합된 스핀 LED가 개발되어, 저온에서 스핀주입에 의해 편광된 빛이 방출되는 현상이 관측되었으나, 실온 이하의 극저온에서만 그와 같은 물성이 나타나고 대부분은 액체질소 온도이하로 낮추어야 하기에 현실적인 응용은 곤란하다.The development of the conventional ferromagnetic semiconductor is mainly carried out by adding Mn, which is a transition metal, to III-V compound semiconductors of GaAs and InAs. In recent years, a heterojunctioned spin LED with a compound semiconductor light emitting diode has been developed, and polarized light is emitted by spin injection at low temperatures, but such properties are exhibited only at cryogenic temperatures below room temperature, and most of them are below liquid nitrogen temperature. The practical application is difficult because it must be lowered.
따라서 최근에는 상온에서 강자성을 띄는 반도체, 즉 상온 강자성 반도체에 대한 연구 개발이 진행되고 있다. 이러한 연구 개발의 결과 중 ZnO를 기초로 하는 모재에 펄스 레이저 증착 방법으로 Co를 넣어 만든 박막이 있으나 상전이 온도가 300K 근처로서, 상온에 근접하긴 했으나 실용성이 있을 만큼 높지 못하다. 나아가서 이와 같은 방법은 재현성이 10% 미만으로 알려져 있어 그 신빙성이 낮다. 특히, 이 종래 기술은 ZnO에 소량의 전이금속을 넣을 때, 전이금속의 양만을 조절함으로서 투명한 상온 강자성 반도체를 만들려고 하고 있으나, 2차상의 형성과 관련된 문제를 완전히 해결하지 못하였다.Therefore, in recent years, research and development on a ferromagnetic semiconductor, that is, a room temperature ferromagnetic semiconductor has been in progress. Among the results of this research and development, there is a thin film made of ZnO-based base material by adding Co by pulse laser deposition method, but the phase transition temperature is near 300K, which is close to room temperature but not high enough for practical use. Furthermore, such a method is known to have a reproducibility of less than 10% and its reliability is low. In particular, this prior art attempts to make a transparent room temperature ferromagnetic semiconductor by controlling only the amount of the transition metal when a small amount of the transition metal is added to ZnO, but has not completely solved the problems related to the formation of the secondary phase.
본 발명은 상기와 같은 문제점을 해결하기 위해 안출된 것으로, 상온에서 강자성을 가지는 반도체 물질을 제공하는 것을 목적으로 한다.The present invention has been made to solve the above problems, an object of the present invention to provide a semiconductor material having ferromagnetic at room temperature.
본 발명의 다른 목적은 상온에서 강자성을 가지는 반도체를 제조하는 방법을 제공하는 데에 있다.Another object of the present invention is to provide a method of manufacturing a semiconductor having ferromagnetic properties at room temperature.
본 발명의 그 밖의 목적, 특정한 장점들 및 신규한 특징들은 첨부된 도면들과 연관된 이하의 상세한 설명과 바람직한 실시예들로부터 더욱 분명해질 것이다.Other objects, specific advantages and novel features of the invention will become more apparent from the following detailed description and preferred embodiments in conjunction with the accompanying drawings.
상기한 목적을 달성하기 위하여 본 발명에 따른 상온 강자성 반도체는, 모재인 SrFeO3와, 상기 SrFeO3에 도핑된 Mo를 포함하며, 상기 SrFeO3 중 Fe와 상기 Mo의 원자구성비가 75% : 25% ~ 65% : 35%로서 화학식 SrFe1 - xMoxO3 (0.25 ≤ x ≤ 0.35)로 표현되는 것을 특징으로 한다.Room temperature, the ferromagnetic semiconductor of the present invention to achieve the above object includes: a base material of SrFeO 3, comprises a doped Mo in the SrFeO 3, the atomic ratio of the SrFeO 3 of the Fe and the Mo 75%: 25% 65%: 35% as represented by the chemical formula SrFe 1 - x Mo x O 3 (0.25≤x≤0.35).
한편, 본 발명에 따른 상온 강자성 반도체 제조 방법은, SrCO3 분말과, Fe2O3 분말과, MoO3 분말을 혼합하되, 상기 Fe2O3 분말 중 Fe와 상기 MoO3 분말 중 Mo의 원자구성비가 75% : 25% ~ 65% : 35%가 되도록 혼합하는 혼합단계와, 상기 혼합된 분말을 소결하는 소결단계를 포함하여 이루어진다. 여기서 상기 소결단계는, 1,000℃~1,300℃를 유지한 상태에서 10시간~24시간 동안 산소 분위기에서 소결하는 것이 바람직하다.Meanwhile, the method for manufacturing a room temperature ferromagnetic semiconductor according to the present invention comprises mixing SrCO 3 powder, Fe 2 O 3 powder, and MoO 3 powder, but the atomic composition ratio of Fe in the Fe 2 O 3 powder and Mo in the MoO 3 powder It comprises a mixing step of mixing so that 75%: 25% ~ 65%: 35%, and a sintering step of sintering the mixed powder. Here, the sintering step is preferably sintered in an oxygen atmosphere for 10 hours to 24 hours in a state of maintaining 1,000 ℃ ~ 1,300 ℃.
한편, 본 발명에 따른 상온 강자성 반도체 제조 방법은, 상기 소결된 분말을 수소 2%부피비, 아르곤 98%부피비의 분위기 하에서 환원하는 단계를 더 포함할 수 있다. 또한 상기 소결된 분말을 타겟으로 하여 기판에 증착하는 단계를 더 포함할 수도 있다.Meanwhile, the method for manufacturing a room temperature ferromagnetic semiconductor according to the present invention may further include reducing the sintered powder in an atmosphere of hydrogen 2% by volume and 98% by volume of argon. The method may further include depositing the sintered powder on a substrate.
본 발명에 따른 상온 강자성 반도체는 경제적으로 저렴하고, 환경친화적이며 상온에서 강자성과 반도성을 동시에 지닌다. 상온에서 강자성이며 반도체인 것인 소재는 전자의 스핀분극을 증가시키므로, 정보처리의 최대화, 최고속화를 요구하는 미래의 과학기술을 만족하기 위해 필요한 전자의 스핀의 기능을 첨가한 소자의 개발인 스핀주입 및 메모리소자 등에 이용될 수 있으므로 그 활용가치가 높다. 그뿐만 아니라, 고밀도 정보 저장, 양자연산(quantum computing)이 가능하여 양자컴퓨터 제작의 토대가 될 수 있으며, 자기광학적 편광의 각도센서 및 광학적 모듈레이터에 이르기까지 매우 다양한 응용성을 가지고 있다.The room temperature ferromagnetic semiconductor according to the present invention is economically inexpensive, environmentally friendly, and has both ferromagnetic and semiconducting properties at room temperature. As a material that is ferromagnetic and semiconductor at room temperature increases spin polarization of electrons, spin is a development of a device that adds the function of electron spin necessary to satisfy future science and technology that requires maximum information processing and maximization. Its use value is high because it can be used for injection and memory devices. In addition, high-density information storage and quantum computing can be used as the basis for quantum computer fabrication, and have a wide variety of applications ranging from magneto-optical polarization angle sensors to optical modulators.
또한 본 발명에 따른 상온 강자성 반도체 제조 방법에 따르면, 나노소재에서부터, 박막, 웨이퍼, 벌크시료 등 다양한 형태로 강자성 반도체를 제조할 수 있으며, 최근까지 자성반도체 연구의 주된 문제점인 2차상의 형성이 없는 균일한 소재를 성장시킬 수 있다. In addition, according to the method for manufacturing a room temperature ferromagnetic semiconductor according to the present invention, ferromagnetic semiconductors can be manufactured in various forms such as nanomaterials, thin films, wafers, and bulk samples, and until recently, there is no formation of a secondary phase, which is a major problem of magnetic semiconductor research. It is possible to grow a uniform material.
도 1은 본 발명에 따른 상온 강자성 반도체의 일실시예의 온도에 따른 비저항값 변화를 도시한 그래프이고,1 is a graph showing a change in the specific resistance value according to the temperature of an embodiment of a room temperature ferromagnetic semiconductor according to the present invention,
도 2는 본 발명에 따른 상온 강자성 반도체의 일실시예의 온도의 역수에 대한 비저항값의 변화를 로그 스케일로 표시한 그래프이며,2 is a graph showing the change in the specific resistance value against the inverse of the temperature of an embodiment of a room temperature ferromagnetic semiconductor according to the present invention on a logarithmic scale,
도 3은 본 발명에 따른 상온 강자성 반도체의 일실시예의 외부 자기장의 변화에 따른 자화밀도 변화를 표시한 그래프이고,3 is a graph showing a change in magnetization density according to a change in an external magnetic field of an embodiment of a room temperature ferromagnetic semiconductor according to the present invention;
도 4는 본 발명에 따른 상온 강자성 반도체의 일실시예의 큐리온도를 측정한 그래프이며,Figure 4 is a graph measuring the Curie temperature of one embodiment of a room temperature ferromagnetic semiconductor according to the present invention,
도 5는 본 발명에 따른 상온 강자성 반도체의 일실시예의 상온에서의 비저상홀효과를 측정한 그래프이고,Figure 5 is a graph measuring the non-bottom Hall effect at room temperature of one embodiment of a room temperature ferromagnetic semiconductor according to the present invention,
도 6은 본 발명에 따른 상온 강자성 반도체 제조 방법의 일실시예의 순서도이다.6 is a flow chart of an embodiment of a method for manufacturing a room temperature ferromagnetic semiconductor according to the present invention.
이하에서는 본 발명에 따른 상온 강자성 반도체의 바람직한 실시예를 상세히 설명한다.Hereinafter, a preferred embodiment of the room temperature ferromagnetic semiconductor according to the present invention will be described in detail.
본 발명에 따른 상온 강자성 반도체는, SrFeO3를 모재로 하되, 모재에 도핑된 Mo를 포함한다.The room temperature ferromagnetic semiconductor according to the present invention includes SrFeO 3 as a base material and includes Mo doped in the base material.
이때 모재인 SrFeO3 중의 Fe와 Mo의 상대적인 원자구성비는 Fe : Mo = 75% : 25%로부터, Mo의 비중을 높여서 Fe : Mo = 65% : 35% 사이의 범위인 것이 바람직하다.At this time, the relative atomic composition ratio of Fe and Mo in the base material SrFeO 3 is preferably in the range of Fe: Mo = 75%: 25%, increasing the specific gravity of Mo: Fe: Mo = 65%: 35%.
결과적으로 Mo가 도핑된 SrFeO3의 결과물은 화학식 SrFe1-xMoxO3 (0.25 ≤ x ≤ 0.35)와 같은 구성을 갖게 된다.As a result, the resultant Mo-doped SrFeO 3 has a structure such as the formula SrFe 1-x Mo x O 3 (0.25 ≦ x ≦ 0.35).
이와 같은 구성을 가진 상온 강자성 반도체의 특성을 분석하여 설명하면 다음과 같다. 설명의 편의를 위하여 SrFe1-xMoxO3에서 x=0.3인 경우를 예로 들어 분석한다.The analysis of the characteristics of the room temperature ferromagnetic semiconductor having such a configuration will be described below. For convenience of explanation, the case where x = 0.3 in SrFe 1-x Mo x O 3 is analyzed as an example.
도 1은 본 발명에 따른 상온 강자성 반도체의 일실시예의 온도에 따른 비저항값 변화를 도시한 그래프이다. 도 1에 도시된 바와 같이, 본 발명에 따른 SrFe0.7Mo0.3O3은 온도가 감소함에 따라 비저항값이 급격히 증가하는 특성을 보여주고 있다. 이를 통해 본 발명에 따른 SrFe0.7Mo0.3O3가 반도체로서의 특성을 갖고 있음을 알 수 있다.1 is a graph illustrating a change in specific resistance value according to temperature of an embodiment of a room temperature ferromagnetic semiconductor according to the present invention. As shown in FIG. 1, SrFe 0.7 Mo 0.3 O 3 according to the present invention shows a characteristic in which the specific resistance increases rapidly as the temperature decreases. Through this, it can be seen that SrFe 0.7 Mo 0.3 O 3 according to the present invention has characteristics as a semiconductor.
도 2는 본 발명에 따른 상온 강자성 반도체의 일실시예의 온도의 역수(1/KBT)에 대한 비저항값의 변화를 로그(logarithmic) 스케일로 표시한 그래프이다. 도 2에 나타난 바와 같이 본 발명에 따른 SrFe0.7Mo0.3O3는 온도 170K 이상에서, 비저항값이 아레니우스 법칙(Arrhenius law) 을 잘 따르고 있음을 알 수 있다. 여기서 KB는 볼츠만상수이고, Ea는 열적인 활성화 에너지(thermal activation energy)이다. 도 2에 나타난 그래프의 기울기로부터 반도체 에너지 간극 Eg = 2E a ∼ 0.4 eV임을 알 수 있다.FIG. 2 is a graph showing the change in the resistivity value with respect to the inverse of the temperature (1 / KBT) of the room temperature ferromagnetic semiconductor according to the present invention on a logarithmic scale. As shown in FIG. 2, the SrFe 0.7 Mo 0.3 O 3 according to the present invention has a specific resistance at a temperature of 170 K or higher, and the Arrhenius law You can see that it follows well. Where K B is Boltzmann's constant and E a is thermal activation energy. It can be seen from the slope of the graph shown in FIG. 2 that the semiconductor energy gap E g = 2 E a -0.4 eV.
도 3은 본 발명에 따른 상온 강자성 반도체의 일실시예의 외부 자기장의 변화에 따른 자화밀도 변화를 표시한 그래프이다. 도 3의 그래프에서 가로축은 외부에서 인가해준 자기장의 세기이며, 세로축은 자화밀도를 측정하여 이를 화학식단위(Formula Unit)가 주는 자기 모멘트로 환산한 값이다. 도 3에 나타난 바와 같이 본 발명에 따른 SrFe0.7Mo0.3O3는 상온에서 화학식단위당 자기 모멘트가 벌크시료에서 0.5 Bohr magneton을 넘으므로, 강자성의 특성이 있음을 알 수 있다.3 is a graph showing a change in magnetization density according to a change in an external magnetic field of an embodiment of a room temperature ferromagnetic semiconductor according to the present invention. In the graph of FIG. 3, the horizontal axis represents the strength of the magnetic field applied from the outside, and the vertical axis measures the magnetization density, which is converted into a magnetic moment given by a formula unit. As shown in FIG. 3, SrFe 0.7 Mo 0.3 O 3 according to the present invention has a ferromagnetic property because the magnetic moment per chemical unit exceeds 0.5 Bohr magneton in a bulk sample at room temperature.
도 4는 본 발명에 따른 상온 강자성 반도체의 일실시예의 큐리온도를 측정한 그래프이다. 도 4에서도 자화밀도는 화학식단위당 자기 모멘트로 환산하여 표기하고 있다. 외부에서 1000 Oe의 자기장을 인가하고 무자력 냉각(Zero Field Cooling: ZFC) 및 자력 냉각(Field Cooling: FC) 조건에서 본 발명에 따른 SrFe0.7Mo0.3O3의 자화밀도를 온도의 변화에 따라 측정하면, 큐리온도(Curie Point)는 절대온도로 550K 근처에서 나타남을 알 수 있다.Figure 4 is a graph measuring the Curie temperature of one embodiment of a room temperature ferromagnetic semiconductor according to the present invention. In Fig. 4, the magnetization density is expressed in terms of magnetic moment per chemical unit. When the magnetic field of 1000 Oe is applied externally and the magnetization density of SrFe 0.7 Mo 0.3 O 3 according to the present invention is measured under the conditions of Zero Field Cooling (ZFC) and Field Cooling (FC) according to the change of temperature The Curie Point is shown at 550K near the absolute temperature.
도 5는 본 발명에 따른 상온 강자성 반도체의 일실시예의 상온에서의 비저상홀효과(Anomalous Hall effect)를 측정한 그래프이다. 도 5에서 가로축은 외부에서 걸어주는 자기장의 세기, 세로축은 홀저항을 나타내는데, 본 발명에 따른 SrFe0.7Mo0.3O3가 강자성의 성질을 가지고 있음을 보여준다.5 is a graph measuring anomalous hall effect at room temperature of an embodiment of a room temperature ferromagnetic semiconductor according to the present invention. In FIG. 5, the horizontal axis represents the strength of the magnetic field, and the vertical axis represents the Hall resistance. The SrFe 0.7 Mo 0.3 O 3 according to the present invention has ferromagnetic properties.
이와 같은 상온 강자성 반도체를 제조하기 위해서는 다음 설명과 같은 과정을 따른다.In order to manufacture such a room temperature ferromagnetic semiconductor, the following process is described.
도 6은 본 발명에 따른 상온 강자성 반도체 제조 방법의 일실시예의 순서도이다.6 is a flow chart of an embodiment of a method for manufacturing a room temperature ferromagnetic semiconductor according to the present invention.
먼저 원재료로서 SrCO3와, Fe2O3와, MoO3를 각각 분말상태로 마련한 후, 상호 혼합시킨다(S100). 이때 각 원재료 분말의 배합 비율은 Fe2O3 중의 Fe와 MoO3 중의 Mo의 상대적인 원자구성비가 Fe : Mo = 75% : 25%로부터, Mo의 비중을 높여서 Fe : Mo = 65% : 35% 사이의 범위인 것이 바람직하다.First, SrCO 3 , Fe 2 O 3 , and MoO 3 are prepared in powder form as raw materials, and then mixed with each other (S100). The compounding ratio of the respective raw material powder is the relative atomic ratio of Fe and MoO 3 of Mo of Fe2O3 Fe: in the range between 35%: Mo = 75%: from 25%, by increasing the proportion of Mo Fe: Mo = 65% It is preferable.
혼합된 분말을 적정 조건에서 소결시킨다(S200). 그러면 각 원재료들이 합성되면서 화학식 SrFe1-xMoxO3 (0.25 ≤ x ≤ 0.35)로 표현되는 상온 강자성 반도체가 생성된다. 이때 소결 조건은 1,000℃~1,300℃를 유지한 상태에서 10시간~24시간 동안인 것이 바람직하며, 소결 분위기는 산소 분위기인 것이 바람직하다.The mixed powder is sintered under appropriate conditions (S200). Then, as each raw material is synthesized, a room temperature ferromagnetic semiconductor represented by the chemical formula SrFe 1-x Mo x O 3 (0.25 ≦ x ≦ 0.35) is produced. At this time, the sintering conditions are preferably for 10 hours to 24 hours in a state of 1,000 to 1,300 ℃, the sintering atmosphere is preferably an oxygen atmosphere.
한편, 소결 단계(S200)에서는 생성되는 상온 강자성 반도체는 페로브스카이트(Perovskite) 구조의 단일상을 가지는 것이 바람직하지만, 현실적으로는 2차상이 생성될 수 있다. 이러한 2차상의 생성을 최소화하기 위해서는 혼합된 분말을 환원시킬 필요가 있다. 이를 위해 수소 2% 부피비, 아르곤 98% 부피비로 혼합된 가스 분위기 하에서 소결된 분말을 환원시키는 단계(S300)를 더 수행하는 것이 바람직하다.On the other hand, in the sintering step (S200), the room temperature ferromagnetic semiconductor is preferable to have a single phase having a perovskite (Perovskite) structure, in reality, the secondary phase can be generated. In order to minimize the formation of this secondary phase it is necessary to reduce the mixed powder. To this end, it is preferable to further perform the step (S300) of reducing the sintered powder in a gas atmosphere mixed in a hydrogen 2% volume ratio, argon 98% volume ratio.
이상의 과정을 통해 상온 강자성 반도체의 분말상 또는 괴상으로 된 벌크시료를 얻을 수 있다. 그러나 벌크 형태로는 활용성이 떨어지므로, 메모리와 같은 전자소자로 응용하기 위해서는 추가적인 공정을 더 거치는 것이 바람직하다.Through the above process, it is possible to obtain a bulk sample in the form of powder or mass of room temperature ferromagnetic semiconductor. However, since it is inferior in the form of bulk, it is preferable to go through an additional process for application to an electronic device such as a memory.
따라서 소결 및 환원된 분말을 타겟으로 하여 기판에 증착시킨다(S400). 그러면 기판에는 상온 강자성 반도체 성분이 박막 형태로 적층된다. 이때, 펄스 레이저 증착(Pulsed Laser Deposition: PLD)방법을 이용하여 박막을 성장시키는 것이 바람직하며 특히 레이저 분자빔 에피탁셜(Laser Molecular Beam Epitaxial: LMBE) 증착은 기존의 PLD 방법과 일반적인 분자빔 에피탁셜(Molecular Beam Epitaxial: MBE) 증착방법의 장점만을 조화시킨 증착방법으로 초고진공으로 박막이 성장하는 표면을 증착과 동시에 RHEED(Reflection High Energy Electron Diffraction)의 세기 진동을 관찰함으로서 박막의 층간성장(layer-by-layer growth)을 확인할 수 있고 이를 이용해 박막의 두께를 원자크기에서 제어할 수 있다. 또한, 타겟 벌크시료의 조성비를 그대로 유지하며 단결정 박막을 만들어 낼 수도 있다.Therefore, the sintered and reduced powder is deposited on the substrate as a target (S400). Then, a room temperature ferromagnetic semiconductor component is stacked in a thin film form. In this case, it is preferable to grow a thin film by using a pulsed laser deposition (PLD) method, and in particular, laser molecular beam epitaxial (LMBE) deposition is performed using a conventional PLD method and a general molecular beam epitaxial (LMBE) method. It is a deposition method that harmonizes the advantages of Molecular Beam Epitaxial (MBE) deposition method and deposits the surface where the thin film grows by ultra-high vacuum and simultaneously observes the intensity vibration of RHEED (Reflection High Energy Electron Diffraction). -layer growth) can be used to control the thickness of the thin film in atomic size. In addition, it is possible to produce a single crystal thin film while maintaining the composition ratio of the target bulk sample.
PLD방법은 레이저로 챔버내부의 표적물질을 기화시켜 단결정위에 박막을 증착하는 방법으로 구조가 간단하고, 복잡한 조성비의 물질도 쉽게 증착할 수 있으며, 높은 녹는점을 가진 물질도 증착이 가능하며, LMBE는 PLD 증착 방법에 원자층 까지도 조절할 수 있게 한 증착 방법이라고 할 수 있다. 원자층 수준의 에피탁시(epitaxy)한 박막을 성장시키기 위해 기판온도, 산소분압 및 레이저의 에너지 밀도 등을 변화시키면서 최적의 증착조건을 찾아야 할 필요가 있다.The PLD method is a method of depositing a thin film on a single crystal by vaporizing the target material in the chamber with a laser. The structure is simple, and it is possible to easily deposit a complex compositional material, and a material having a high melting point can be deposited. It can be said that the deposition method that can control the atomic layer to the PLD deposition method. In order to grow an epitaxial thin film at the atomic layer level, it is necessary to find the optimum deposition conditions while changing the substrate temperature, oxygen partial pressure, and laser energy density.
앞에서 설명되고, 도면에 도시된 본 발명의 일 실시예는, 본 발명의 기술적 사상을 한정하는 것으로 해석되어서는 안 된다. 본 발명의 보호범위는 청구범위에 기재된 사항에 의하여만 제한되고, 본 발명의 기술분야에서 통상의 지식을 가진 자는 본 발명의 기술적 사상을 다양한 형태로 개량 변경하는 것이 가능하다. 따라서 이러한 개량 및 변경은 통상의 지식을 가진 자에게 자명한 것인 한 본 발명의 보호범위에 속하게 될 것이다.An embodiment of the present invention described above and illustrated in the drawings should not be construed as limiting the technical idea of the present invention. The protection scope of the present invention is limited only by the matters described in the claims, and those skilled in the art can change and change the technical idea of the present invention in various forms. Therefore, such improvements and modifications will fall within the protection scope of the present invention, as will be apparent to those skilled in the art.
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| KR20240059844A (en) | 2022-10-28 | 2024-05-08 | 한국화학연구원 | Ferromagnetic film and manufacturing method thereof |
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| CN115259227B (en) * | 2022-09-15 | 2023-10-27 | 郑州大学 | Method for preparing room-temperature ferromagnetic molybdenum oxide nanosheets by using supercritical carbon dioxide |
| KR20240059844A (en) | 2022-10-28 | 2024-05-08 | 한국화학연구원 | Ferromagnetic film and manufacturing method thereof |
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