Growth, structure, and morphology of van der Waals epitaxy Cr1+δTe2 films
Tóm tắt
The preparation of two-dimensional magnetic materials is a key process to their applications and the study of their structure and morphology plays an important role in the growth of high-quality thin films. Here, the growth, structure, and morphology of Cr1+δTe2 films grown by molecular beam epitaxy on mica with variations of Te/Cr flux ratio, growth temperature, and film thickness have been systematically investigated by scanning tunneling microscopy, reflection high-energy electron diffraction, scanning electron microscope, and X-ray photoelectron spectroscopy. We find that a structural change from multiple phases to a single phase occurs with the increase in growth temperature, irrespective of the Cr/Te flux ratios, which is attributed to the desorption difference of Te atoms at different temperatures, and that the surface morphology of the films grown at relatively high growth temperatures (≥ 300 °C) exhibits a quasi-hexagonal mesh-like structure, which consists of nano-islands with bending surface induced by the screw dislocations, as well as that the films would undergo a growth-mode change from 2D at the initial stage in a small film thickness (2 nm) to 3D at the later stage in thick thicknesses (12 nm and 24 nm). This work provides a general model for the study of pseudo-layered materials grown on flexible layered substrates.
Tài liệu tham khảo
Gong C, et al. Discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals. Nature. 2017;546(7657):265–9.
Huang B, Clark G, Navarro-Moratalla E, Klein DR, Cheng R, Seyler KL, Zhong D, Schmidgall E, McGuire MA, Cobden DH. Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit. Nature. 2017;546(7657):270–3.
Lasek K, Li J, Kolekar S, Coelho PM, Zhang M, Wang Z, Batzill M. Synthesis and characterization of 2D transition metal dichalcogenides: recent progress from a vacuum surface science perspective. Surf Sci Rep. 2021;76(2):100523.
Zhang X, Lu Q, Liu W, Niu W, Sun J, Cook J, Vaninger M, Miceli PF, Singh DJ, Lian S-W. Room-temperature intrinsic ferromagnetism in epitaxial CrTe2 ultrathin films. Nat Commun. 2021;12(1):1–9.
Wu H, Zhang W, Yang L, Wang J, Li J, Li L, Gao Y, Zhang L, Du J, Shu H. Strong intrinsic room-temperature ferromagnetism in freestanding non-van der Waals ultrathin 2D crystals. Nat Commun. 2021;12(1):1–8.
Huang M, Ma Z, Wang S, Li S, Li M, Xiang J, Liu P, Hu G, Zhang Z, Sun Z. Significant perpendicular magnetic anisotropy in room-temperature layered ferromagnet of Cr-intercalated CrTe2. 2D Mater. 2021;8(3):031003.
Coughlin AL, et al. Near degeneracy of magnetic phases in two-dimensional chromium telluride with enhanced perpendicular magnetic anisotropy. ACS Nano. 2020;14(11):15256–66.
Meng L, Zhou Z, Xu M, Yang S, Si K, Liu L, Wang X, Jiang H, Li B, Qin P. Anomalous thickness dependence of Curie temperature in air-stable two-dimensional ferromagnetic 1T-CrTe2 grown by chemical vapor deposition. Nat Commun. 2021;12(1):1–8.
Chen C, Chen X, Wu C, Wang X, Ping Y, Wei X, Zhou X, Lu J, Zhu L, Zhou J. Air-stable 2D Cr5Te8 nanosheets with thickness-tunable ferromagnetism. Adv Mater. 2022;34(2):2107512.
Zhang X, Wang B, Guo Y, Zhang Y, Chen Y, Wang J. High Curie temperature and intrinsic ferromagnetic half-metallicity in two-dimensional Cr3X4 (X = S, Se, Te) nanosheets. Nanoscale Horiz. 2019;4(4):859–66.
Kang N, Wan W, Ge Y, Liu Y. Diverse magnetism in stable and metastable structures of CrTe. Front Phys. 2021;16(6):63506.
Zhao D, Zhang L, Malik IA, Liao M, Cui W, Cai X, Zheng C, Li L, Hu X, Zhang D. Observation of unconventional anomalous Hall effect in epitaxial CrTe thin films. Nano Res. 2018;11(6):3116–21.
Wang Y, Yan J, Li J, Wang S, Song M, Song J, Li Z, Chen K, Qin Y, Ling L. Magnetic anisotropy and topological Hall effect in the trigonal chromium tellurides Cr5Te8. Phys Rev B. 2019;100(2):024434.
Zhou L, Chen J, Chen X, Xi B, Qiu Y, Zhang J, Wang L, Zhang R, Ye B, Chen P. Topological hall effect in traditional ferromagnet embedded with black-phosphorus-like bismuth nanosheets. ACS Appl Mater Int. 2020;12(22):25135–42.
Huang M, Gao L, Zhang Y, Lei X, Hu G, Xiang J, Zeng H, Fu X, Zhang Z, Chai G. Possible topological hall effect above room temperature in layered Cr12Te2 ferromagnet. Nano Lett. 2021;21(10):4280–6.
Tang B, Wang X, Han M, Xu X, Zhang Z, Zhu C, Cao X, Yang Y, Fu Q, Yang J, Li X, Gao W, Zhou J, Lin J, Liu Z. Phase engineering of Cr5Te8 with colossal anomalous Hall effect. Nat Electron. 2022;5(4):224–32.
Lasek K, Coelho PM, Gargiani P, Valvidares M, Mohseni K, Meyerheim HL, Kostanovskiy I, Zberecki K, Batzill M. Van der Waals epitaxy growth of 2D ferromagnetic Cr(1+δ)Te2 nanolayers with concentration-tunable magnetic anisotropy. Appl Phys Rev. 2022;9(1):011409.
Lasek K, Coelho PM, Zberecki K, Xin Y, Kolekar SK, Li J, Batzill M. Molecular beam epitaxy of transition metal (Ti-, V-, and Cr-) tellurides: from monolayer ditellurides to multilayer self-intercalation compounds. ACS Nano. 2020;14(7):8473–84.
Zhang X, Ambhire SC, Lu Q, Niu W, Cook J, Jiang JS, Hong D, Alahmed L, He L, Zhang R. Giant topological Hall effect in van der Waals heterostructures of CrTe2/Bi2Te3. ACS Nano. 2021;15(10):15710–9.
Li M-Y, Su S-K, Sheng-Kai W, et al. How 2D semiconductors could extend Moore’s law. Nature. 2019;567(7747):169–70.
Nathan A, Chalamala BR. Special issue on flexible electronics technology, part II: materials and devices. Proc IEEE. 2005;93(8):1391–3.
Lou Z, Wang L, Jiang K, Wei Z, Shen G. Reviews of wearable healthcare systems: materials, devices and system integration. Mater Sci Eng R. 2020;140:100523.
Souri H, Bhattacharyya D. Highly stretchable multifunctional wearable devices based on conductive cotton and wool fabrics. ACS Appl Mater Inter. 2018;10(24):20845–53.
Zhao J, Fu Y, Xiao Y, Dong Y, Wang X, Lin L. A naturally integrated smart textile for wearable electronics applications. Adv Mater Technol. 2020;5(1):1900781.
Son D, Lee J, Qiao S, Ghaffari R, Kim J, Lee JE, Song C, Kim SJ, Lee DJ, Jun SW. Multifunctional wearable devices for diagnosis and therapy of movement disorders. Nat Nanotechnol. 2014;9(5):397–404.
Gao W, Emaminejad S, Nyein HYY, Challa S, Chen K, Peck A, Fahad HM, Ota H, Shiraki H, Kiriya D. Fully integrated wearable sensor arrays for multiplexed in situ perspiration analysis. Nature. 2016;529(7587):509–14.
Fan FR, Tang W, Wang ZL. Flexible nanogenerators for energy harvesting and self-powered electronics. Adv Mater. 2016;28(22):4283–305.
Huang J, Wang H, Wang X, Gao X, Liu J, Wang H. Exchange bias in a La0.67Sr0.33MnO3/NiO heterointerface integrated on a flexible mica substrate. ACS Appl Mater Inter. 2020;12(35):39920–5.
Koma A. Van der Waals epitaxy: a new epitaxial growth method for a highly lattice-mismatched system. Thin Solid Films. 1992;216(1):72–6.
Utama MIB, Zhang Q, Zhang J, Yuan YW, Belarre FJ, Arbiol J, Xiong QH. Recent developments and future directions in the growth of nanostructures by van der Waals epitaxy. Nanoscale. 2013;5(9):3570–88.
Bitla Y, Chu Y-H. MICAtronics: a new platform for flexible X-tronics. FlatChem. 2017;3:26–42.
Jiang J, Bitla Y, Huang C-W, Do TH, Liu H-J, Hsieh Y-H, Ma C-H, Jang C-Y, Lai Y-H, Chiu P-W. Flexible ferroelectric element based on van der Waals heteroepitaxy. Sci Adv. 2017;3(6):e1700121.
Chu Y-H. Van der Waals oxide heteroepitaxy. NPJ Quantum Mater. 2017;2(1):1–5.
Zhou H, Xie J, Mai MF, Wang J, Shen XQ, Wang SY, Zhang LH, Kisslinger K, Wang H-Q, Zhang JX, Li Y, Deng JH, Ke SM, Zeng XR. High-quality AZO/Au/AZO sandwich film with ultralow optical loss and resistivity for transparent flexible electrodes. ACS Appl Mater Inter. 2018;10(18):16160–8.
Helander M, Greiner M, Wang Z, Lu Z. Note: binding energy scale calibration of electron spectrometers for photoelectron spectroscopy using a single sample. Rev Sci Instrum. 2011;82(9):096107.
Dijkstra J, Weitering H, Van Bruggen C, Haas C, De Groot R. Band-structure calculations, and magnetic and transport properties of ferromagnetic chromium tellurides (CrTe, Cr3Te4, Cr2Te3). J Phys: Condens Matter. 1989;1(46):9141.
Ross M, Takeda H, Wones DR. Mica polytypes: systematic description and identification. Science. 1966;151(3707):191–3.
Tatecama H, Shimoda S, Sudo T. The crystal structure of synthetic MgIV mica. Zeitschrift für Kristallographie Cryst Mater. 1974;139(1–6):196–206.
Shimada K, Saitoh T, Namatame H, Fujimori A, Ishida S, Asano S, Matoba M, Anzai S. Photoemission study of itinerant ferromagnet Cr1-δTe. Phys Rev B. 1996;53(12):7673.
Allen GC, Tucker PM, Wild RK. X-ray photoelectron/Auger electron spectroscopic study of the initial oxidation of chromium metal. J Chem Soc Faraday Trans Mol Chem Phys. 1978;74:1126–40.
Chua R, Zhou J, Yu X, Yu W, Gou J, Zhu R, Zhang L, Liu M, Breese MB, Chen W. Room temperature ferromagnetism of monolayer chromium telluride with perpendicular magnetic anisotropy. Adv Mater. 2021;33(42):2103360.
Purbawati A, Coraux J, Vogel J, Hadj-Azzem A, Wu NJ, Bendiab N, Jegouso D, Renard J, Marty L, Bouchiat V, Sulpice A, Aballe L, Foerster M, Genuzio F, Locatelli A, Mentes TO, Han ZV, Sun XD, Nunez-Regueiro M, Rougemaille N. In-plane magnetic domains and neel-like domain walls in thin flakes of the room temperature CrTe2 Van der Waals ferromagnet. ACS Appl Mater Inter. 2020;12(27):30702–10.
Moulder JF, Stickle WF, Sobol PE, Bomben KD. Handbook of X-ray photoelectron spectroscopy. Minnesota: Perkin-Elmer Corporation; 1992. p. 26.
Nie Y, Barton AT, Addou R, Zheng Y, Walsh LA, Eichfeld SM, Yue R, Cormier CR, Zhang C, Wang Q, Bang C, Robinson JA, Kim M, Vandenberghe W, Colombo L, Cha P-R, Wallace RM, Hinkle CL, Cho K. Dislocation driven spiral and non-spiral growth in layered chalcogenides. Nanoscale. 2018;10(31):15023–34.
Cheung SH, Zheng LX, Xie MH, Tong SY, Ohtani N. Initial stage of GaN growth and its implication to defect formation in films. Phys Rev B. 2001;64(3):033304.
Roy A, Guchhait S, Dey R, Pramanik T, Hsieh C-C, Rai A, Banerjee SK. Perpendicular magnetic anisotropy and spin glass-like behavior in molecular beam epitaxy grown chromium telluride thin films. ACS Nano. 2015;9(4):3772–9.
Burton W-K, Cabrera N, Frank F. The growth of crystals and the equilibrium structure of their surfaces. Philos Trans R Soc Lond Ser A Math Phys Sci. 1951;243(866):299–358.
Hutchinson W. Recrystallisation textures in iron resulting from nucleation at grain boundaries. Acta Metall. 1989;37(4):1047–56.
Sefta F, Hammond KD, Juslin N, Wirth BD. Tungsten surface evolution by helium bubble nucleation, growth and rupture. Nucl Fusion. 2013;53(7):073015.