Smart Advanced Materials/Devices by Laser/Plasma Process

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In this research program, development of pulsed laser deposition (PLD) using KrF excimer laser and YAG laser has been studied to obtain high-quality thin films and devices. Dynamics of laser produced plasmas was also investigated to understand the growth mechanism of thin films at various deposition conditions in PLD process. We proposed the new PLD process combined with plasma ion implantation and dielectric barrier discharge. In carbon based material preparation, laser induced fluorescence (LIF) method was introduced and showed that C_2 and C_3 exist near the carbon target and off-axis area far the target center. Carbon radicals C, C_2, and C_3 dominate optical property of the diamondlike carbon films. Heterostructures consisting of oxide thin films such as superconducting Y-Ba-Cu-O, ferroelectrics Pb-Zr-Ti-O, colossal magnetoresistivity La-Sr-Mn-O, photonics ZnO have been prepared for field effect transistor, magnetic sensor, light emitting device, and nonvolatile memory device.The CNx thin films deposited in NO ambient gas (50mTorr) showed N/C ratio of 1.0. The ferroelectric Pb-Zr-Ti-O/superconducting Y-Ba-Cu-O/YSZ coated Si substrate heterostructure had the good ferroelectric properties of the remanent polarization (Pr) of 20 μC/cm^2 and the coercive field (Ec) of 40 kV/cm.The La-Sr-Mn-O/MgO showed resistivity peak temperature of 330K and the magnetoresistance of 15% (H=0.7T) at room temperature. The Au/Pb-Zr-Ti/La-Sr-Mn-O/MgO capacitor had Pr of 22 μC/cm^2 and Ec of 27kV/cm. The PLD provides high quality ZnO thin films. The deposited films shows (002), (003) XRD peaks corresponding to c-axis length of 0.529nm. The PLD process developed here is a promising technique to deposit 21 century materials aiming for nanostructures such as nanoparticles, nanocrystals and nanoparticles embedded devices.