Uncooled Infrared Detectors Pbtio <sub> 3 </ Sub> Ferroelectric Thin Films By Sol-gel Preparation And Performance Study

Pyroelectric array that utilize the technology of integration of the ferroelectric thin film with semi-conductor circuit have received recent attention. The thesis aims to fabricate ferroelectric thin film by Sol-Gel method with its potential application in non-cooling pyroelectric detector. The detailed fabrication process and the physics properties of the obtained films are presented in this work. The thesis is composed of preparation of MgO buffer layer and the research on the electrical properties of PLCT/MgO/Si structure, growth of highly (100) oriented Zr-rich PZT and PLCT ferroelectric thin films as well as the study of their physical properties. MgO thin films have been prepared by a novel and simple Sol-Gel method using magnesium nitrate and collodion as the starting materials for the first time. The relation of collodion and annealing process with the microstructure and morphology of the MgO fihns are systematically examined. The thickness of the prepared MgO films is uniform and there is no obvious diffusion between MgO and Si substrate. Simple nebuhized spray pyrolysis method has been applied to prepare MgO thin films with (100) preferential orientation on (100) Si substrates by using magnesium acetate as starting reactants. Meanwhile, the electrical properties of Au/PLCT/MgO/Si films are reported for the first time. The simple nebuhized spray pyrolysis method overcomes the disadvantages of conventional ultrasonic spray pyrolysis. The experimental results reveal that the substrate temperature and the oxygen flow played important roles in the formation of (100)-oriented MgO films. The optimal growth condition for the (100)-oriented MgO thin films is that the substrate temperature sets at 6000C and the oxygen flow is 2.5L/min. The quality of the derived MgO thin films is much better than those obtained from Sot-Gel process. Meanwhile, the electrical properties of Au/PLCT/MgO/Si films are reported for the first time. The results indicate that PLCT thin films grew on the thinner MgO buffer layer exhibit the better ferroelectric properties than those of PLCT films grew on the thicker MgO buffer layer. The memory window of PLCT/(1 5Onm)MgO/Si film is about 0.4V. The investigations of the leakage mechanism show that Au/PLCT/N4g0/Si films exhibit ohm law in low voltage while in high electrical field the law will make some variation. At present, there has few reports concerning the (100)-oriented Zr-rich PZT thin films. In the thesis, highly (100)-preferentially oriented Zr-rich lead zirconate titanate PZT8O/20 and PZT85/15, and random oriented PZT7O/30 thin films were successfully prepared on (111) Pt coated Si substrates by the sol-gel process with rapid thermal annealing (RTA). The study finds that not only there exists some difference in the way of the growth between the oriented and random PZT films but also there has distinct contrast of the dielectric and ferroelectric properties between them. Higher dielectric constant and lower dielectric loss of the (100)-oriented PZT with good ferroelectric properties can be found. The results show that highly (100)-oriented PZT85/15 films exhibit higher remnant polarization (2Pr41 .4tC/cm2) and higher coercive field (2E=h11kV/cm) than randomly oriented PZT7O/30 films (2P,.33.4tC/cm2 and 2E 106kV/cm respectively). Highly (100)-oriented La amid Ca doped PbTiO3 ferroelectric thin films are successfully prepared on Pt/Ti/Si02/Si substrates by a simple sot-gel technique. The influences of film compo...