Electrical and optical properties of microwave dielectric thin films prepared by pulsed laser deposition

Bi-2(Zn1/3Nb2/3)(2)O-7, BiZN, materials possess high dielectric constant an d low loss factor in microwave frequency region. They have good potential f or device application, especially in the form of thin films. However, the m icrowave dielectric properties of a thin film are very difficult to be accu rately measured. Evaluation on the dielectric behavior of the films through the performance of the microstrip line devices made of these films involve s metallic conduction and stray field losses. A novel measuring technique, which can directly evaluate the microwave dielectric properties of a thin f ilm is thus urgently needed. In this paper, BiZN thin films were grown on [100] MgO single crystal subst rates using pulsed laser deposition process. The high-frequency dielectric properties of thus obtained thin films were determined using optical transm ission spectroscopy (OTS). The [100] preferentially oriented films with pyr ochlore structure can be obtained for the thin films deposited at 400-600 d egreesC substrate temperature under 0.1 mbar oxygen pressure. OTS measureme nts reveal that the index of refraction (n = 1.95-2.35) and absorption coef ficient (kappa = 0.28 x 10(-4)-2.25 x 10(-4) nm(-1)) of the films vary insi gnificantly with the crystallinity of the BiZN films.