| INORGANIC MATERIALS AND CERAMIC MATRIX COMPOSITES |
|
|
|
|
|
| Progress in Preparation of Diluted Ferromagnetic MnxGe1-x Quantum Dots by Molecular Beam Epitaxy |
| HUANG Xunji1,2, YANG Jie1,2, LI Guangyang1,2, WANG Chong1,2, YANG Yu2,3
|
1 School of Materials Science and Engineering, Yunnan University, Kunming 650091;
2 International JointResearch Center for National Optoelectronic Energy Materials, Yunnan University, Kunming 650091;
3 School of Energy, Yunnan University, Kunming 650091 |
|
|
|
Abstract Diluted magnetic semiconductors (DMSs) integrate the dual properties of semiconductor materials and magnetic materials by simultaneously utilizing the charge and spin characteristics of electrons. The use of charge carriers and their spins makes it possible for spintronic devices to be used for information storage, transmission and processing. Consequently, Mn-doped Ge quantum dots(QDs) diluted ferromagnetic semiconductors, as an important part of the microelectronics industry, have aroused enormous interests because of its compatibility with current Si microelectronics and the possibility to possess higher Curie temperature (TC) than those of group Ⅲ-Ⅴ materials. The prepared MnxGe1-x QDs spintronic devices exhibit excellent performances including small size, low energy consumption, fast data processing, high integration and favorable stability, which will play a crucial role in the future development of spintronic devices.
Although Mn doped group Ⅳ MnxGe1-x QDs DMSs materials are considered to be ideal candidates for room temperature controllable electronic spin devices and controllable ferromagnetic properties. However, the MnxGe1-x QDs DMSs materials with high performance and stability are still confronted with great challenges.Ⅰ. Although high TC of the system can be obtained by raising the concentration of magnetic dopant in the matrix, the solubility limit of Mn dopant in Ge is far lower than the dopant concentration which endows the system with high TC. Ⅱ. The high concentration of Mn dopant in Ge1-xMnx QDs is likely to cause the formation of intermetallic precipitates (Mn5Ge3 and Mn11Ge8). Ⅲ. Low growth temperature and low surface diffusivity are demanded for incorporating Mn into Ge under the state much higher than chemical equilibrium, while high growth temperature and high surface diffusivity are always required in self-assembly growth of QDs. Namely, achieving higher doping levels of metastable may become a breakthrough point for enhancing TC in DMSs. Ⅳ. The theoretical explanation of ferromagnetism, the origin of high TC and enhancement mechanism of TC are still unclear and worth further exploration.
Therefore, great attempts have been made and fruitful results have been achieved by researchers in optimizing the preparation process of MnxGe1-x QDs films by selecting suitable growth parameters in recent years. Ⅰ. The TC of MnxGe1-x QDs is raised above 400 K. Ⅱ. It is defined that the TC of intermetallic precipitates (Mn5Ge3 and Mn11Ge8) are 296 K and 270 K, which tends to room temperature. Ⅲ. The electric-field-controlled ferromagnetism and the magnetotransport properties have been found. Electric-field manipulation of ferromagnetism temperature has been raised over 300 K for the first time, which was attributed to the quantum confinement effect. Ⅳ. Due to the existence of quantum effects in MnxGe1-x QDs, the modulated doping of boron (B) can increase the hole concentration in the MnxGe1-x QDs, which contributed to enhancing the TC of the MnxGe1-x QDs.
This review offers a retrospection of the research efforts with respect to the MnxGe1-x diluted ferromagnetic semiconductor materials, and provides elaborated descriptions about the MnxGe1-x QDs prepared by molecular beam epitaxy (MBE). And the effects of growth parameters on the morphology and magnetic properties of QDs are also introduced. The difficulties that remain to be solved in the current research are briefly described, and the application prospects for the material in the field of microelectronics are proposed.
|
|
Published: 18 October 2018
|
|
|
|
|
1 Janisch R, Gopal P, Spaldin N A. Transition metal-doped TiO2 and ZnO-present status of the field[J].Journal of Physics Condensed Matter,2005,17(27):18.
2 Wang L, Liu T, Jia Q, et al. Research Update: Strain and composition effects on ferromagnetism of Mn0.05Ge0.95 quantum dots[J].Apl Materials,2016,4(4):153.
3 Wang L, Liu T, Hu X, et al. Carrier effects on ferromagnetism of MnxGe1-x quantum dots[J].Applied Physics Letters,2017,111(7):072103.
4 Dietl T. A ten-year perspective on dilute magnetic semiconductors and oxides[J].Nature Materials,2010,9(12):965.
5 Reuther H, Talut G, Mücklich A, et al. Magnetism in Ge by ion implantation with Fe and Mn[J].Journal of Physics D: Applied Physics,2012,45(39):395001.
6 Bolduc M, Awo-Affouda C, Stollenwerk A, et al. Above room temperature ferromagnetism in Mn-ion implanted Si[J].Physical Review B,2005,71(3):3302.
7 Bonanni A. Ferromagnetic nitride-based semiconductors doped with transition metals and rare earths[J].Semiconductor Science & Technology,2007,22(9):R41.
8 Cohen G, Fleurov V, Kikoin K. Vacancy mediated ferromagnetic interaction in TiO2 doped with magnetic ions[J].Journal of Applied Physics,2007,101(9):R59.
9 Coey J M D. High-temperature ferromagnetism in dilute magnetic oxides[J].Journal of Applied Physics,2005,97(10):854.
10 Kelly P J, Arnell R D. Magnetron sputtering: A review of recent developments and applications[J].Vacuum,2000,56(3):159.
11 Meyer F, Schwebel C, Pellet C, et al. Epitaxial growth of single-crystal Si1-xGex on Si(100) by ion beam sputter deposition[J].Thin Solid Films,1990,184(1):117.
12 Gunnella R, Morresi L, Pinto N, et al. Magnetization of epitaxial MnGe alloys on Ge(111) substrates[J].Surface Science,2005,577(1):22.
13 Yoon I T, Park C J, Kang T W. Ferromagnetism in Mn-implanted Ge/Si nanostructure material[J].Journal of Superconductivity & Novel Magnetism,2010,23(1):115.
14 Chang L L, Ploog K. Molecular beam epitaxy and heterostructures[M].Springer Netherlands: Martinus Nijhoff Publishers,1985.
15 Xiu F, Wang Y, Kim J, et al. Electric-field-controlled ferromagne-tism in high-Curie-temperature Mn0.05Ge0.95 quantum dots[J].Nature Materials,2010,9(4):337.
16 Yong J C, Chang H K, Han S K, et al. Ferromagnetic Ge1-xMx (M=Mn, Fe, and Co) Nanowires[J].Chemistry of Materials,2008,20(14):4694.
17 Kazakova O, Kulkarni J S, Holmes J D, et al. Room-temperature ferromagnetism in MnxGe1-x nanowires[J].Physical Review B Condensed Matter,2005,72(9):094415.
18 Guchhait S, Jamil M, Ohldag H, et al. Ferromagnetism in Mn-implanted epitaxially grown Ge on Si(100)[J].Physical Review B Condensed Matter,2011,84(2):1651.
19 Jamet M, Barski A, Devillers T, et al. High-Curie-temperature ferromagnetism in self-organized Ge1-xMnx nanocolumns[J].Nature Materials,2006,5(8):653.
20 Nie T, Tang J, Kou X, et al. Enhancing electric-field control of ferromagnetism through nanoscale engineering of high-TC MnxGe1-x nanomesh[J].Nature Communications,2016,7:12866.
21 Xiu F, Yong W, Jin Z, et al. Electric-field controlled ferromagnetism in MnGe magnetic quantum dots[J].Nano Reviews,2012,2:5896.
22 Xiu F, Wang Y, Kim J, et al. Room-temperature electric-field controlled ferromagnetism in Mn0.05Ge0.95 quantum dots[J].ACS Nano,2010,4(8):4948.
23 Nie T, Kou X, Tang J, et al. Nanoengineering of an Si/MnGe quantum dot superlattice for high Curie-temperature ferromagnetism[J].Nanoscale,2017,9(9):3086.
24 Dolph M C, Kim T, Yin W, et al. Magnetic properties of ion implanted Ge1-xMnx thin films solidified through pulsed laser melting[J].Journal of Applied Physics,2011,109(9):093917.
25 Nie T, Tang J, Wang K L. Quest for high-Curie temperature Ge1-x-Mnx diluted magnetic semiconductors for room-temperature spintronics applications[J].Journal of Crystal Growth,2015,425:279.
26 Nolph C A, Kassim J K, Floro J A, et al. Addition of Mn to Ge quantum dot surfaces-interaction with the Ge QD {105} facet and the Ge(001) wetting layer[J].Journal of Physics Condensed Matter,2013,25(31):315801.
27 Yin W, Kell C D, He L, et al. Enhanced magnetic and electrical properties in amorphous Ge∶Mn thin films by non-magnetic codoping[J].Journal of Applied Physics,2012,111(3):033916.
28 Kobayashi N P, Talin A A, Davydov A V, et al. Magnetic doping of Ge-quantum dots: Growth studies exploring the feasibility of modulating QD properties[J].Invited Paper,2014,9174:917400.
29 Gotoh K, Oshima R, Sugaya T, et al. Effect of deposition rate on the characteristics of Ge quantum dots on Si (001) substrates[J].Thin Solid Films,2014,557:80.
30 Mouton I, Lardé R, Talbot E, et al. Composition and morphology of self-organized Mn-rich nanocolumns embedded in Ge: Correlation with the magnetic properties[J].Journal of Applied Physics,2012,112(11):113918.
31 Portavoce A, Abbes O, Spiesser A, et al. Mn-Ge nanocluster formation vs. diluted magnetic semiconductuor formation[J].Scripta Materialia,2015,100:70.
32 Réotier P D D, Prestat E, Bayle-Guillemaud P, et al. Core-shell nanostructure in a Ge0.9Mn0.1 film observed via structural and magnetic measurements[J].Physical Review B,2015,91:24.
33 Park Y D, Hanbicki A T, Erwin S C, et al. A group-Ⅳ ferromagnetic semiconductor: MnxGe1-x[J].Science,2002,295(5555):651.
34 Prestat E, Porret C, Favre-Nicolin V, et al. Investigations of segregation phenomena in highly strained Mn-doped Ge wetting layers and Ge quantum dots embedded in silicon[J].Applied Physics Letters,2014,104(10):102409.
35 Ma Y J, Zhong Z, Yang X J, et al. Factors influencing epitaxial growth of three-dimensional Ge quantum dot crystals on pit-patterned Si substrate[J].Nanotechnology,2013,24(1):015304.
36 Awschalom D D, Flatté M E. Challenges for semiconductor spintronics[J].Nature Physics,2007,3(3):153.
37 Tanaka M, Yokoyama M, Hai P N, et al. Chapter 11 properties and functionalities of MnAs/Ⅲ-Ⅴ hybrid and composite structures[J].Semiconductors & Semimetals,2008,82(08):455.
38 Tsui F, He L, Ma L, et al. Novel germanium-based magnetic semiconductors[J].Physical Review Letters,2003,91(17):177203.
39 Bihler C, Jaeger C, Vallaitis T, et al. Structural and magnetic pro-perties of Mn5Ge3 clusters in a dilute magnetic germanium matrix[J].Applied Physics Letters,2006,88(11):3020.
40 Braak H, Gareev R R, Bürgler D E. Magnetic characteristics of epitaxial Ge(Mn,Fe) diluted films—A new room temperature magnetic semiconductor？[J].Journal of Magnetism & Magnetic Materials,2005,286:46.
41 Cho S, Choi S, Hong S C, et al. Ferromagnetism in Mn-doped Ge[J].Physical Review B,2002,66(3):3606.
42 Li A P, Shen J, Thompson J R, et al. Ferromagnetic percolation in MnxGe1-x dilute magnetic semiconductor[J].Applied Physics Letters,2005,86(15):R1865.
43 Jungwirth T, Sinova J, Masek J, et al. Theory of ferromagnetic (Ⅲ,Mn) Ⅴ semiconductors[J].Review of Modern Physics,2006,78(3).
44 Matsukura F, Ohno H, Shen A, et al. Transport properties and origin of ferromagnetism in (Ga,Mn)As[J].Physical Review B,1998,57(4):R2037.
45 Dietl T, Ohno H, Matsukura F, et al. Zener model description of ferromagnetism in zinc-blende magnetic semiconductors[J].Science,2000,287(5455):1019.
46 Bougeard D, Ahlers S, Trampert A, et al. Clustering in a precipitate-free GeMn magnetic semiconductor[J].Physical Review Letters,2006,97(23):237202.
47 Gao W, Wang L, Hou D, et al. The effect of Co ion implantation on Ge1-xMnx films[J].Applied Surface Science,2011,257(21):8871.
48 Deng J X, Tian Y F, Yan S S, et al. Magnetism of amorphous Ge1-xMnx magnetic semiconductor films[J].Journal of Applied Physics,2008,104(1):013905.
49 Yada S, Sugahara S, Tanaka M. Magneto-optical and magnetotransport properties of amorphous ferromagnetic semiconductor Ge1-x-Mnx thin films[J].Applied Physics Letters,2008,93(19):1849.
50 Wang K L, Xiu F. Quest of electric field controlled spintronics in MnGe[J].Thin Solid Films,2010,518(6):S104.
51 Devillers T, Jamet M, Barski A, et al. Structure and magnetism of self-organized Ge1-xMnx nanocolumns on Ge(001)[J].Physical Review B,2007,76(20):5306.
52 Yu I S, Jamet M, Devillers T, et al. Spinodal decomposition to control magnetotransport in (Ge,Mn) films[J].Physical Review B,2010,82(3):1558.
53 Jamet M, Barski A, Devillers T, et al. High-Curie-temperature ferromagnetism in self-organized Ge1-xMnx nanocolumns[J].Nature Materials,2006,5(8):653.
54 Conta G, Amato G, Cosson M, et al. Experimental insight into the magnetic and electrical properties of amorphous Ge1-xMnx[J].Science and Technology of Advanced Materials,2017,18(1):34.
55 Stroppa A, Picozzi S, Continenza A, et al. Electronic structure and ferromagnetism of Mn-doped group-Ⅳ semiconductors[J].Physical Review B,2003,68(15):846.
56 Tang J, Nie T. Spin transport in Ge nanowires for diluted magnetic semiconductor-based nonvolatile transpinor[C]∥ECS and Smeq Joint International Meeting. Los Angeles,2014,64(6).
57 Knobel R, Samarth N, Crooker S A, et al. Spin-polarized quantum transport and magnetic field-dependent carrier density in magnetic two-dimensional electron gases[J].Physica E: Low-dimensional Systems and Nanostructures,2000,6(1-4):786.
58 Jiang J H, Wu M W. Electron spin relaxation in bulk Ⅲ-Ⅴ semiconductors from a fully microscopic kinetic spin Bloch equation approach[J].2009,79(12):125206.
59 Xiu F, Ovchinnikov I V, Upadhyaya P, et al. Voltage-controlled ferromagnetic order in MnGe quantum dots[J].Nanotechnology,2010,21(37):375606.
60 Kassim J, Nolph C, Jamet M, et al. Ge1-xMnx heteroepitaxial quantum dots: Growth, morphology, and magnetism[J].Journal of Applied Physics,2013,113(7):073910.
61 Yoon I T, Park C J, Lee S W, et al. Ferromagnetism in self-assembled Ge quantum dots material followed by Mn-implantation and annealing[J].Solid-State Electronics,2008,52(6):871.
62 Ma X, Lou C. The ferromagnetic properties of Ge magnetic quantum dots doped with Mn[J].Applied Surface Science,2012,258(7):2906.
63 Ma X, Lou C. The electromagnetic properties of the Mn doped Ge/Si quantum dots diodes[J].Materials Science and Engineering: B,2013,178(2):174.
64 Le T G, Nam D N H, Dau M T, et al. The effects of Mn concentration on structural and magnetic properties of Ge1-xMnx diluted magnetic semiconductors[J].2012,292(1):012012.
65 Schulthess T C, Butler W H. Electronic structure and magnetic interactions in Mn doped semiconductors[J].Journal of Applied Physics,2001,89(11):7021.
66 Schilfgaarde M V, Mryasov O N. Anomalous exchange interactions in Ⅲ-Ⅴ dilute magnetic semiconductors[J].Physical Review B,2001,63(63):233205.
67 Wang Y, Zou J, Zhao Z, et al. Mn behavior in Ge0.96Mn0.04 magnetic thin films grown on Si[J].Journal of Applied Physics,2008,103(6):651.
68 Wang Y, Zou J, Zhao Z, et al. Direct structural evidences of Mn11Ge8 and Mn5Ge2 clusters in Ge0.96Mn0.04 thin films[J].Applied Physics Letters,2008,92(10):951.
69 Chiba D, Sawicki M, Nishitani Y, et al. Magnetization vector manipulation by electric fields[J].Nature,2008,455(7212):515.
70 Kassim J, Nolph C, Jamet M, et al. Mn solid solutions in self-assembled Ge/Si(001)quantum dot heterostructures[J].Applied Phy-sics Letters,2012,101(24):242407.
71 Zhou X, Shi B, Jiang Z, et al. Boron-mediated growth of Ge quantum dots on Si(100) substrate[J].Thin Solid Films,2000,369(1):92.
72 Ohno H, Chiba D, Matsukura F, et al. Electric-field control of ferromagnetism[J].Nature,2000,408(6815):944.
73 Chiba D, Matsukura F, Ohno H. Electric-field control of ferromagnetism in (Ga,Mn)As[J].Applied Physics Letters,2006,150(16):951.
74 Myers R C, Sheu B L, Jackson A W, et al. Antisite effect on hole-mediated ferromagnetism in (Ga,Mn)As[J].Physical Review B,2006,74(74):2952.
75 Nikonov D E, Bourianoff G I. Operation and modeling of semiconductor spintronics computing devices[J].Journal of Superconductivity & Novel Magnetism,2008,21(8):479.
76 Wolf S A, Awschalom D D, Buhrman R A, et al. Spintronics: A spin-based electronics vision for the future[J].Science,2001,294(5546):1488.
77 utic＇ I, Fabian J, Sarma S D. Spintronics: Fundamentals and applications[J].Microelectronics Reliability,2004,30(2):323.
78 Tang J, Wang C Y, Chang L T, et al. Electrical spin injection and detection in Mn5Ge3/Ge/Mn5Ge3 nanowire transistors[J].Nano Letters,2013,13(9):4036.
79 Nazmul A M, Kobayashi S, Sugahara S, et al. Electrical and optical control of ferromagnetism in Ⅲ-Ⅴ semiconductor heterostructures at high temperature (~100 K)[J].Japanese Journal of Applied Phy-sics,2004,43(43):L233.
80 Nepal N, Luen M O, Zavada J M, et al. Electric field control of room temperature ferromagnetism in III-N dilute magnetic semiconductor films[J].Applied Physics Letters,2009,94(13):944.
81 Chen J, Wang K L, Galatsis K. Electrical field control magnetic phase transition in nanostructured MnxGe1-x[J].Applied Physics Letters,2007,90(1):012501. |
|
|
|
渝公网安备50019002502923号 © Editorial Office of Materials Reports.
2018, Vol. 32 
