Pulsed Laser Deposition Of Srtio <sub> 3 </ Sub> Thin Film Dielectric Properties

Pulsed laser deposition (PLD) is used to produce SrTiO3 film. Through the optimization of the growth parameters of the PLD system, the effect of microstructure on the dielectric property has been analyzed. The effects of substrate temperature, oxygen pressure, laser energy and oxygen annealing on SrTiO3 film growth and dielectric property have been investigated by AFM and XRD. Compared the XRD results of the STO films deposited at different oxygen pressures, the out-of-plane lattice parameter increases with the decrease of the oxygen pressures and the out-of-plane lattice parameter will be elongated under the low oxygen pressure. After the depositing of films at oxygen pressure of 2Pa and 10Pa and testing with the parallel capacitors, their tunabilities under the bias between –5V and 5V is 53.2% and 33.2% respectively. This means the elongation of the lattice parameter of STO film along the direction of applied electric field could improve the dielectric tunability of the film in the same direction. Under the temperature of 80K,the dielectric constant of the STO film deposited at the oxygen pressure of 2Pa increases with the increase of testing signal level, while the dielectric constant of the STO film deposited at the oxygen pressure of 10Pa varies a little. The temperature dependence of εof the film deposited at 2Pa shows a peak, compared with that of the film deposited at 10Pa. The amplitude peak decreases and shifts to higher temperature with the increase of the frequency of testing signal. The results show the concentration of oxygen vacancies in the film affects its dielectric behavior greatly. The testing signal with high amplitude can stimulate the dielectric relaxation structure of the film with high concentration of oxygen vacancies and increase the dielectric constant. Compared the XRD results of the STO films on MgO and LAO, the films show tensile and compressive stress, respectively. The tunability of the parallel capacitor on films on MgO and LAO under the bias between –40V and 40V are 26.3% and 22.4%. While experiencing tensile stress, the tunability of the STO films on MgO could increase.