Legal System With Pld On Different Substrates Prepared Lasrcoo <sub> 3 </ Sub> Thin-film And Thin Film Properties

La₀.5Sr₀.5CoO₃ (LSCO) has being applied in fuel cells, gas sensors and as electrodes in ferroelectric memories due to its relatively high electronic and ionic conductivity. Since LSCO has a pseudo-cubic perovskite structure, excellent structural compatibility with Pb-based oxide perovskite ferroelectrics, LSCO has been used as the electrode in the Pb(Zr,Ti)O3,(Pb,La)(Zr,Ti)O3, which can improve the fatigue of ferroelectric memory cells. My work mainlyfocused on growth of LSCO film and application in electrode, as well as its eFect of laser induced thermoelectric voltage (LITV). LSCO films have been grown on four differentsubstrates (Si, SiO2/Si, Pt/Ti/SiO/Si, LaAlO₃(LAO)) by pulsed laser deposition (PLD)technique. The growth conditions, structures, surface morphology and resistivity of the films have been studied. By optimizing growth conditions, the problem of micro cracks shown up on the film surface has been solved and the density of droplets on film also decreased in a large extent, thereafter the films with high quality were achieved. LITV signal was reported for the first time in LSCO films on vicinal LaAlO₃ (LAO) substrate. The main results include:1. LITV signal has been observed in LSCO film on vicinal LAO substrates. In comparisonwith LITV signal of LaCaMnO₃ films, it demonstrated much faster response time. Thelaser-energy dependence of LITV peak-voltage can be fitted well with a linear function.2. We also prepared LSCO polycrystalline targets of La_1-xSr_xCoO₃(x=0.1, 0.3, 0.5, 0.6). LITV signal were also found in the films of La_1-xSr_xCoO₃ (x=0.3, 0.6), but La₀.5Sr₀.5CoO₃ film had the fastest response time.3. The influences of substrates and growth temperature on film structure have been investigated. LSCO films were grown nearly epitaxially on LaAlO₃ substrates. LSCO films deposited on single-crystalline Si substrates demonstrate non-preferential orientation, while the films deposited on SiO₂/Si substrates show [110] preferential orientation which display a tendency of non-preferential orientation with increased deposition temperature. One the other hand, the films deposited on Pt/Ti/SiO2/Si substrates changed from [110] preferential orientation to [100] preferential orientation with growth temperature increasing.4. Micro cracks on LSCO film surface originate from the mismatch between film materialand substrates. The mismatch includes lattice mismatch and mismatch of thermal expansion coefficients. The influences of post-annealing and in-situ annealing on film surface morphology have been studied. By in-situ annealing and slow cooling, the micro cracks can be eliminated.5. By optimizing growth conditions, the density of droplet on film also decreased in a large extent.6. The effects of substrates on film resistivity (P) have been studied. The result shows: P si (pa means film resistivity of the film on A)> Psice/si > Plao> p Pt/n/sice/si (forP Fvri/siO2/5i5 the contribution of substrate was not taken into account). Furthermore, theeffects of growth temperature, annealing temperature and oxygen pressure on the film resistivity have been also investigated. The optimal experimental condition for lowering film resistivity was obtained.