$YBa_2Cu_3O_x$ thin films on MgO substrate were deposited with Pulsed Laser Deposition(PLD) method. Firstly, they were deposited at temperature below general optimum deposition temperature. There existed optimal oxygen pressures in each deposition temperature. High critical temperatures at optimal oxygen pressures were explained by c-axis orientation degrees with XRD and in-plane orientation degrees with φ-scan.
Secondly, the effects of laser energy power, laser targeting frequency, heat treatment on the electrical characteristics and surface morphology were studied. Good quality film were obtained at 1.7J/㎠ energy density, lower frequency. The effect of heat treatment after deposition on film quality is insignificant.
At last, the surface resistances were measured using microstrip line λ/2 resonator at 77K, 4.25GHz. The surface resistance of film deposited at 730℃, 100mtorr was about 40㏁. This value was superior to that of film using MOCVD (Metal Organic Chemical Vapour Deposition). The lower surface resistance can be obtained at lower laser targeting frequency. That was explained by c-axis flat surface at lower laser targeting frequency (lower deposition rate).
The aim of this work is to investigate the possibility of $YBa_2Cu_3O_x$ films deposition on GaAs at low temperature and construction of hybrid microwave integrate circuit. And this work can give good information of acquiring a good quality films using PLD at low temperature.