Strongly c-axis oriented Pb(ZrxTi1−x)O3 (PZT) thin films with tetragonal perovskite structure (0.45≤x≤0.52) were epitaxially grown on (100)Pt/(100)MgO substrates using metalorganic chemical vapor deposition. Film thickness could be varied by altering the growth time. The electrical properties of PZT thin films sharply change below a thickness of 0.5 μm: the dielectric constant and remanent polarization decrease while the coercive field increases. These phenomena are explained by a model in which a layer with low dielectric constant exists in series with the normal PZT layer. The origins of this layer are systematically studied and found to be the intrinsic stress produced by the coalescence of crystal grains.

Strongly c-axis oriented Pb (ZrxTi1-x) O3 thin films were successfully grown on (100) Pt/(100) MgO substrate using the metalorganic chemical vapor deposition (MOCVD) method . The electrical properties of PZT thin films with thickness of 2ƒÊm are almost the same values of PZT single crystal . But they sharply change below film thickness of 0.5ƒÊm: dielectric constant and remanent polarization decrease , and coercive field increases. These phenomena are explained by the model that low dielectric constant layer exist in series with normal PZT layer.The origins of this layer is considered to be the intrinsic stress produced by the coalescence of crystal grains .

Lanthanum-modified lead zirconate titanate (PLZT) thin films (0.3∼0.4 µm) have been prepared on Pt/SiO2/Si substrates at 650°C by the metal-organic chemical vapor deposition (MOCVD) method. The electrical properties of the films were examined as a function of lanthanum content. The relative dielectric constants increased as the La content increased to about 5 at%, and beyond this value, it became constant at 600. The remanent polarization and coercive field decreased from 22 to 1 µC/cm2 and from 90 to 20 kV/cm with increasing La content in the range of 0∼11 at%, respectively. The leakage current density decreased considerably with the addition of La, and was 8×10-9 A/cm2 at an applied voltage of 5 V. The switched charge densities of PLZT films showed almost no change up to switching cycles of 1×1012 at a bipolar pulse of ±5 V.

In0.2Ga0.8As/GaAs strained quantum wells (SQWs) were grown on GaAs (111)A just-oriented, 1° off and 5° off toward [110]- and [001]-oriented substrates. Dependence of strain relaxation on substrate orientation was studied by photoluminescence (PL) spectroscopy. Samples grown on GaAs (111)A 5° off toward [001]-oriented substrates showed the best optical characteristics and this substrate orientation was chosen for making p-i-n diodes. The PL spectrum shows the influence of a built-in electric field due to the piezoelectric effect. The blueshift of PL peaks with applied bias was demonstrated in a p-i-n structure. The PL peak corresponding to a 10 nm SQW blueshifted as much as 24 meV with only 1.2 V applied reverse bias.

Effects of carrierstorage layer of InAs/GaAs short period superlattice on photocurrent in GaAs/GaAlAs multi quantum well structure