Theoretical And Experimental Researches Of ABO₃ Perovskite Thin Film On The Growth Kinetics

Multi-element oxide thin films are strategically important and are expected to have widespread industrial uses. For instance, ABO3 perovskite thin films have wide applications such as memories, sensors, filters, and microwave components, et al. In order to prepare thin films with good quality, the researches on the growth mechanism of such thin films are very necessary.In this thesis, the theoretical and experimental researches of ABO3 perovskite thin film on the growth kinectics were carried out. A three dimensional algorithm for simulating multi-element oxide thin films deposited by Metal Reactive Co-deposition at atomic level is presented, by which the software was developed and the morphologies of PbTiO3 thin films at their initial stage were simulated. For some ABO3 type thin film deposition methods with molecular level ion sources, it was assumed that ABO3 type thin films grow on the basis of formation and diffusion of the crystal unit cell, then a three dimensional model and algorithm for simulating homogenous epitaxial multi-element oxide thin film growth were developed, by which the morphology evolution, the growth modes, Refractive High Energy Electron Diffraction(RHEED) curves, Root Mean Square (RMS) and the initial islands of ABO3 thin films were simulated in detailed, and their relationships were discussed. PbTiO3 thin films were prepared with the low growth rate (0.185nm/min) and the temperature of 600℃ for 1min, 3min and 6min, respectively by Radio Frequency Magnetron Sputtering method, the size, the number and the height of which wereanalyzed by Atom Force Microscopy (AFM). And at last, the theoretical and experimental researches results in this thesis are reviewed and analyzed.From the main contents in this thesis mentioned above, several innovative features can be concluded:1. A three dimensional algorithm for simulating multi-element oxide thin films deposited by Metal Reactive Co-deposition at atomic level was developed, by which the morphologies of PbTiO3 thin films at their initial stage deposited with the temperature of 800K-900K and the deposition rate of 0.01ML/S-1MIVS were simulated. Results show that deposition rate and temperature play a very important role in the initial process of PbTiO3-thin film growth. With the rising of deposition temperature and the decreasing of deposition rate, the size of initial nuclear gets larger and the number of nuclear gets smaller. With the same deposition rate, the size of initial nuclear gets larger and the number of nuclear gets smaller with the rising of the deposition temperature.2. For some thin film deposition methods with molecular level ion sources, it was assumed that ABO3 type thin films grow on the basis of formation and diffusion of the crystal unit cell, then a three dimensional model and algorithm for simulating homogenous epitaxial multi-element oxide thin film growth were developed. By this mode, the morphology evolution, the growth modes, Refractive High Energy Electron Diffraction(RHEED) curves, Root Mean Square (RMS) and the initial islands of ABO3 thin films with the different deposition rate (0.01ML/S-IML/S) and the different deposition temperature (800K-1000K) were simulated in detailed, and their relationships were discussed. With the low deposition rate, this model can be used to make sure of the experimental parameters for depositing the epitaxial thin films by assuming the proper diffusion active energy.3. PbTiO3 thin films were prepared on the single crystal substrate of Si(100) with the low growth rate (0.185nm/min) by Radio Frequency Magnetron Sputtering method, and the size, the number and the height of PbTiO3/Si(100) thin films were analyzed by Atom Force Microscopy (AFM). The experimental results showed thatPbTiO3/Si(100) thin films grow under this deposition conditions with island mode.4. The detailed analyses of cross-view of thin films by the high height (z direction) resolution of AFM indicates that the height of some islands is nearly 0.4 nm and the height of other islands is nearly the integral time of the length of the PbTiO3 crystal unit cell. It can be concluded that at their initial stage, PbTiO3 extra thin films grow through the formation and the diffusion of unit cells on the surface. Such result confirms that the assumption of ABO3 type thin films growing on the basis of formation and diffusion of the crystal unit cells is in reason for the thin film deposition methods with molecular level deposition ion sources.5. By the model basing on the unit cells, RHEED curves of ABO3 type thin films were simulated with the deposition rate of 0.01ML/S and the deposition temperature of 600K, 700K, 800K, 900K and 1000K. RHEED simulation curves have the same variation with the experimental RHEED curves of SrTiO3 homo-epitaxy thin films reported by other author.