Structural and electrical characterization of advanced electronic materials.

摘要

The structural and electrical characterization of following electronic materials is reported in this research: (a) oxides of Sn and Si formed by rapid isothermal processing (RIP), (b) group II-A fluoride dielectric thin films on Si and InP substrates, and (c) high temperature superconducting YBa{dollar}sb2{dollar}Cu{dollar}sb3{dollar}O{dollar}sb{lcub}rm 7-x{rcub}{dollar} (YBCO) thin films deposited by metalorganic chemical vapor deposition (MOCVD) on yttrium stabilized zirconium oxide (YSZ) and Si substrates. The structural characteristics of these materials obtained by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS) are correlated with the electrical properties obtained by capacitance-voltage (C-V), current-voltage (I-V), and resistance-current (R-I) measurements. The superiority of RIP (significant part of the source spectra in the ultraviolet and visible region) over the conventional furnace processing (with blackbody radiations mainly in the infrared region) is clearly demonstrated by the results of Sn and Si oxidation. RIP provides a single phase on SnO{dollar}sb2{dollar}, a high chemically homogeneous interface, as well as improved electrical characteristics. Only in case of in situ RIP, high quality solid phase epitaxial growth of group II-A fluorides (CaF{dollar}sb2{dollar} and SrF{dollar}sb2{dollar}) films on Si (111), InP (100), and InP (111) substrates has been observed. Using conventional furnace heating as the source of energy, the YBCO thin films deposited on YSZ and BaF{dollar}sb2{dollar}/YSZ substrates by MOCVD resulted in {dollar}Tsb{lcub}c{rcub}{dollar}'s of 50 and 80 K, respectively. The films on BaF{dollar}sb2{dollar}/YSZ substrates were textured with most of the grains in c- or a-axis oriented. YBCO thin films grown on BaF{dollar}sb2{dollar}Si substrates were also well-structured and superconducting (with {dollar}Tsb{lcub}c{rcub}{dollar} = 73 K). By using RIP assisted MOCVD instead, very high quality YBCO films can be deposited at a substrate temperature as low as 720{dollar}spcirc{dollar}C on YSZ substrate. The results presented in this thesis clearly demonstrated the advantages of rapid isothermal processing over conventional furnace processing.