Taking the full advantage of the conformal growth characterizing atomic layer deposition(ALD),the possibility to grow Co thin films,with thickness from several tens down to few nanometers on top of a granular topologi...Taking the full advantage of the conformal growth characterizing atomic layer deposition(ALD),the possibility to grow Co thin films,with thickness from several tens down to few nanometers on top of a granular topological insulator(TI)Sb2Tes film,exhibiting a quite high surface roughness(2-5 nm),was demonstrated.To study the Co growth on the Sb2Tes substrate,we performed simultaneous Co depositions also on sputtered Pt substrates for comparison.We conducted a thorough chemical-structural characterization of the Co/Sb2Tes and Co/Pt heterostructures,confirming for both cases,not only an excellent conformality,but also the structural continuity of the Co layers.X-ray diffraction(XRD)and high-resolution transmission electron microscope(HRTEM)analyses evidenced that Co on Sb2Te3 grows preferentially oriented along the[0oe]direction,following the underlying rhombohedric substrate.Differently,Co crystallizes in a cubic phase oriented along the[111]direction when deposited on Pt.This work shows that,in case of deposition of crystalline materials,the ALD surface selectivity and conformality can be extended to the definition of local epitaxy,where in-plane ordering of the crystal structure and mosaicity of the developed crystallized grains are dictated by the underlying substrate.Moreover,a highly sharp and chemically-pure Co/Sb2Tes interface was evidenced,which is promising for the application of this growth process for spintronics.展开更多
基金We acknowledge the MP1402-Hooking together the European research in atomic layer deposition(HERALD)COST action and the Horizon 2020 project SKYTOP"Skyrmion-Topological Insulator and Weyl Semimetal Technology"(FETPROACT-2018-01,n.824123)Efforts at Wayne State University were supported by the U.S.National Science Foundation(Grant No.CHE-1607973)and EMD Performance Materials.
文摘Taking the full advantage of the conformal growth characterizing atomic layer deposition(ALD),the possibility to grow Co thin films,with thickness from several tens down to few nanometers on top of a granular topological insulator(TI)Sb2Tes film,exhibiting a quite high surface roughness(2-5 nm),was demonstrated.To study the Co growth on the Sb2Tes substrate,we performed simultaneous Co depositions also on sputtered Pt substrates for comparison.We conducted a thorough chemical-structural characterization of the Co/Sb2Tes and Co/Pt heterostructures,confirming for both cases,not only an excellent conformality,but also the structural continuity of the Co layers.X-ray diffraction(XRD)and high-resolution transmission electron microscope(HRTEM)analyses evidenced that Co on Sb2Te3 grows preferentially oriented along the[0oe]direction,following the underlying rhombohedric substrate.Differently,Co crystallizes in a cubic phase oriented along the[111]direction when deposited on Pt.This work shows that,in case of deposition of crystalline materials,the ALD surface selectivity and conformality can be extended to the definition of local epitaxy,where in-plane ordering of the crystal structure and mosaicity of the developed crystallized grains are dictated by the underlying substrate.Moreover,a highly sharp and chemically-pure Co/Sb2Tes interface was evidenced,which is promising for the application of this growth process for spintronics.
