title: Welding of Semiconductor Nanowires by Coupling Laser-Induced Peening and Localized Heating.
abstract: We demonstrate that laser peening coupled with sintering of CdTe nanowire films substantially enhances film quality and charge transfer while largely maintaining basic particle morphology. During the laser peening phase, a shockwave is used to compress the film. Laser sintering comprises the second step, where a nanosecond pulse laser beam welds the nanowires. Microstructure, morphology, material content, and electrical conductivities of the films are characterized before and after treatment. The morphology results show that laser peening can decrease porosity and bring nanowires into contact, and pulsed laser heating fuses those contacts. Multiphysics simulations coupling electromagnetic and heat transfer modules demonstrate that during pulsed laser heating, local EM field enhancement is generated specifically around the contact areas between two semiconductor nanowires, indicating localized heating. The characterization results indicate that solely laser peening or sintering can only moderately improve the thin film quality; however, when coupled together as laser peen sintering (LPS), the electrical conductivity enhancement is dramatic. LPS can decrease resistivity up to a factor of ~10,000, resulting in values on the order of ~10(5) Ω-cm in some cases, which is comparable to CdTe thin films. Our work demonstrates that LPS is an effective processing method to obtain high-quality semiconductor nanocrystal films.
authors.affiliation: Purdue University, School of Mechanical Engineering, West Lafayette, IN 47907, USA.|Purdue University, Birck Nanotechnology Center, West Lafayette, IN 47906, USA.
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Rickey
authors.affiliation: Purdue University, Birck Nanotechnology Center, West Lafayette, IN 47906, USA.|Purdue University, School of Industrial Engineering, West Lafayette, IN 47907, USA.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Nian
authors.affiliation: Los Alamos National Lab, Center for Integrated Nanotechnology, Division of Materials Physics and Application, Los Alamos, NM 87545, USA.
authors.forename: Genqiang
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Purdue University, School of Mechanical Engineering, West Lafayette, IN 47907, USA.|Purdue University, Birck Nanotechnology Center, West Lafayette, IN 47906, USA.
authors.forename: Liangliang
authors.initials: L
authors.lastname: Chen
authors.affiliation: Purdue University, Birck Nanotechnology Center, West Lafayette, IN 47906, USA.|Qatar Foundation, Qatar Environment and Energy Research Institute, Doha, Qatar.
authors.forename: Sergey
authors.initials: S
authors.lastname: Suslov
authors.affiliation: Purdue University, School of Mechanical Engineering, West Lafayette, IN 47907, USA.|Purdue University, Birck Nanotechnology Center, West Lafayette, IN 47906, USA.|SRM Research Institute, SRM University, Chennai, 603203, India.
authors.forename: S Venkataprasad
authors.initials: SV
authors.lastname: Bhat
authors.affiliation: Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50010, USA.
authors.forename: Yue
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Purdue University, School of Mechanical Engineering, West Lafayette, IN 47907, USA.|Purdue University, Birck Nanotechnology Center, West Lafayette, IN 47906, USA.|Purdue University, School of Industrial Engineering, West Lafayette, IN 47907, USA.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Cheng
authors.affiliation: Purdue University, School of Mechanical Engineering, West Lafayette, IN 47907, USA.|Purdue University, Birck Nanotechnology Center, West Lafayette, IN 47906, USA.
authors.forename: Xiulin
authors.initials: X
authors.lastname: Ruan