Mass transfer and nano-fabrication by ultrafast laser interactions on plasmonic thin films

• Main Authors: Bo-Han Chen, 陳柏翰
• Other Authors: Din Ping Tsai
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/79637936667514481925

碩士 === 國立臺灣大學 === 應用物理所 === 98 === Laser-induced forward transfer (LIFT) is a simple, fast, one-step process technology, which utilizes the short pulse laser to remove the material from a donor thin film to a receiver substrate. In this thesis, we present a method of the deposited dots by using femto-second LIFT for the gold thin films with the thickness: 20, 30, and 40 nm. Each gold thin film was deposited on a glass substrate by a sputter in an argon chamber with the pressure 0.5 Pa. The growth rate of the gold thin film is 0.2 nm/s. The samples were mounted on a x-y-z stage that positions the sample with a resolution of 0.4 nm relative to a 100X microscope objective and is subsequently irradiated by the Ti:sapphire laser (wavelength λ= 800 nm) with pulse duration of 140 fs and 80 MHz repetition rate. The topography of sample is studied by atomic force microscopy (AFM). Through the observaed morphologies of the receiver side and donor side, the following three zones can be observed. (1) Below the first laser fluence threshold, JT1, no structure formation on the donor film and the receiver substrate was found. (2) Between JT1 and second fluence threshold, JT2, the donor film forms a cylindrical shaped bump, with the size around 18 nm (thickness) x 250 nm (diameter), and gold was transferred to the receiver substrate and formed an island-like geomorphology with nanometer grains. Their sizes are around 5 nm (thickness) x 20 nm (diameter) for LIFT 20 nm-thick donor film. We attribute this phenomenon to phase explosion occurring almost in the superheated liquid free surface of source film. (3) Above JT2, the donor film is ablated and the elevated rim structure, which diameter size is around 300 nm. In receiver substrate, the deposited dots form a disk shaped, which size is around 27 nm (thickness) x 900 nm (diameter) for LIFT 30 nm-thick donor film. Possible mechanisms leading to the observed dots form the resolution limits of this technique are also discussed. The dots of nanothickness thin films via laser pulses may provide a simple and efficient method for fabrication of nanoscale structures, e.g. plasmonic devices. Thus, LIFT technique provides a relatively simple method for the combination of the multiple dissimilar materials within a single microdevice.