Investigation On Properties Of La_1-xSr_xCrO₃ Thin Films By Pulsed Laser Deposition

Strontium?Sr?doped lanthanum chromites?Lai-xSrXCrO3,LSCO?,belonging to the perovskite family,has been widely applied in many fields with stable structure,capacity of defects accommodated,excellent conductivity and certain optical transmittance,such as solid fuel cells,sensors,high temperature equipment and so on.With the limitation of conventional Si-based electronic devices,La_1-xSr_xCrO₃ as a p-type semiconductor oxides has great value in fabricating devices such as memory devices,p-n junctions,CMOS,junction field-effect transistors,switching circuit etc.Faced with the lack of p-type semiconductor oxide materials,it is meaningful and necessary to carry on the research of p-type La_1-xSr_xCrO₃ thin films.Pulsed Laser Deposition?PLD?is one of most promising techniques for the forming high quality thin films and widely used in the growth of numerous complex-oxide film materials.So the p-type La_1-xSr_xCrO₃ thin films were deposited using PLD.That have many advantages such as densification,growth rates and thickness can be controlled,less pollution at high vacuum environment etc which are very important to study the performance of the complex-oxide thin films.It is more challenging,for the reports about the growth of La_1-xSr_xCrO₃ thin films using PLD is relatively less at present.In this paper,La_1-xSr_xCrO₃ thin films were deposited on differently commercial substrates by PLD and its performance has been investigated.The main research contents include the following parts:1.In the first place,La_1-xSr_xCrO₃ phase-purity polycrystalline target was prepared by the conventional soled-state reaction method and the initial physical properties were carried out.A series of LaCrO3 samples was prepared by PLD at single crystal LaAlO3 substrate with different substrate temperature?T?and cavity oxygen partial pressure?P?.The results show that the optimal condition of thin films growth from P-T growth phase diagram of epitaxial LaCrO3 is 0.1 Pa-1.0 Pa and 600? which lays the foundation of the deposition and performance of La_1-xSr_xCrO₃ thin films.2.After that,polycrystalline LaCrO3 thin films were deposited on Pt/Ti/SiO2/Si substrates by pulsed laser deposition and used to fabricate the simple Au/LCO/Pt devices like a sandwich.It is found that the unipolar RS behavior in the Au/LCO/Pt devices exhibits the merits of a high resistance ratio,excellent endurance/retention characteristics.At the same time,we explained the RS mechanism with the Ohmic conduction and the Schottky emission and the rupture of conducting filaments with the redox reaction under the Joule heating effect.3.Finally,epitaxial La_1-xSr_xCrO₃?0.00?x?0.50?thin films were deposited on LaAlO3 and?La,Sr??Al,Ta?O3 substrates by pulsed laser deposition.By the study of electrical properties using a small polaron hopping?SPH?model,we obtained the activation energy from different thin film samples and the optimal condition of thin film growth with previously.At the same time,electrical properties of different Sr-doped also were studied.Whereafter,the epitaxial La_1-xSr_xCrO₃?0.25?thin films grown on Nb:SrTiO3 substrates using the same method and backward diodelike rectifying properties of the p-n heterojunctions was prepared and test.