title: Thermal dewetting with a chemically heterogeneous nano-template for self-assembled L1(0) FePt nanoparticle arrays.
abstract: A design for the fabrication of metallic nanoparticles is presented by thermal dewetting with a chemically heterogeneous nano-template. For the template, we fabricate a nanostructured polystyrene-b-polydimethylsiloxane (PS-b-PDMS) film on a Si|SiO2 substrate, followed by a thermal annealing and reactive ion etching (RIE) process. This gives a template composed of an ordered hexagonal array of SiOC hemispheres emerging in the polystyrene matrix. After the deposition of a FePt film on this template, we utilize the rapid thermal annealing (RTA) process, which provides in-plane stress, to achieve thermal dewetting and structural ordering of FePt simultaneously. Since the template is composed of different composition surfaces with periodically varied morphologies, it offers more tuning knobs to manipulate the nanostructures. We show that both the decrease in the area of the PS matrix and the increase in the strain energy relaxation transfer the dewetted pattern from the randomly distributed nanoparticles into a hexagonal periodic array of L10 FePt nanoparticles. Transmission electron microscopy with the in situ heating stage reveals the evolution of the dewetting process, and confirms that the positions of nanoparticles are aligned with those of the SiOC hemispheres. The nanoparticles formed by this template-dewetting show an average diameter and center-to-center distance of 19.30 ± 2.09 nm and 39.85 ± 4.80 nm, respectively. The hexagonal array of FePt nanoparticles reveals a large coercivity of 1.5 T, much larger than the nanoparticles fabricated by top-down approaches. This approach offers an efficient pathway toward self-assembled nanostructures in a wide range of material systems.
authors.affiliation: Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan. chlai@mx.nthu.edu.tw.
authors.forename: Liang-Wei
authors.initials: LW
authors.lastname: Wang
authors.affiliation: Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan. chlai@mx.nthu.edu.tw.
authors.forename: Chung-Fu
authors.initials: CF
authors.lastname: Cheng
authors.affiliation: Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan. chlai@mx.nthu.edu.tw.
authors.forename: Jung-Wei
authors.initials: JW
authors.lastname: Liao
authors.affiliation: Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan.
authors.forename: Chiu-Yen
authors.initials: CY
authors.lastname: Wang
authors.affiliation: Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan. chlai@mx.nthu.edu.tw.
authors.forename: Ding-Shuo
authors.initials: DS
authors.lastname: Wang
authors.affiliation: Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan. chlai@mx.nthu.edu.tw.
authors.forename: Kuo-Feng
authors.initials: KF
authors.lastname: Huang
authors.affiliation: Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan. chlai@mx.nthu.edu.tw.
authors.forename: Tzu-Ying
authors.initials: TY
authors.lastname: Lin
authors.affiliation: Department of Chemical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Rong-Ming
authors.initials: RM
authors.lastname: Ho
authors.affiliation: Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan. chlai@mx.nthu.edu.tw.
authors.forename: Lih-Juann
authors.initials: LJ
authors.lastname: Chen
authors.affiliation: Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan. chlai@mx.nthu.edu.tw.
authors.forename: Chih-Huang
authors.initials: CH
authors.lastname: Lai