Resistance Change Effect In SrTiO₃/Si?001? Isotype Heterojunction By Pulsed Laser Deposition

Since the high-Tc superconduction and colossal magnetoresistance were observed in the perovskite oxide,much attention has been focused on the novel properties such as ferroelectric,dielectric,ferromagnetic,and superconduction in the perovskite oxides.Owing to these superior properties,the perovskite oxides have been used in many application fields.To combine these excellent properties in the monolithic configuration and to fabricate the oxide intelligent devices,the all-oxide magnetic tunnel junction,p-n junctions,field-effect transistors have been studied by many groups.Among them,the perovskite-silicon devices,which combine the novel properties of perovskite oxide with the traditional silicon based intelligence,are with great potential application for the next generation of oxide electronics.Compared to the conventional semiconductor devices,the ones of oxides could be expected to exhibit characteristics,such as magnetic behavior.Moreover,oxide p-n junctions are expected to work at high temperature where the conventional semiconductor p-n junctions may not be competent.As an important perovskite oxide,strontium titanate?SrTiO₃,STO?,which has a high dielectric constant at room temperature,has been expected to work as the dielectric capacitor in the next generation for resistive random access memory?RRAM?in very large scale integrated devices.For commensurate STO/Si?001?,the interface is structurally far more complex,connecting a diamond structure?Silicon?with a perovskite?STO?.The high reactivity of silicon with many elements and their oxides presents a formidable challenge to the integration of functional oxides with silicon,as does the tendency of a pristine silicon surface to rapidly form its own oxide.This presents a particular challenge for oxides,imposing severe demands on stoichiometry and impurity content,which in turn require suitable methods with concomitant sensitivity.The dominant native point defects in the close packed ABO₃ structure are expected to be vacancies.Point and extended defects in oxides often influence,and can control,both transport and the characteristic physical property,ferroelectricity,providing opportunities for nanoscale engineering.While the importance of oxygen nonstoichiometry in oxide epilayers has been established,the existence and nature of cation nonstoichiometry has received less attention.Investigations of STO application in semiconductor electronic devices can be done by growing STO film on silicon wafer.Several technique have been reported for growing STO thin film on Si substrate such as molecular beam epitaxy and pulsed laser deposition.Here we will discuss the deposition of STO film using PLD technique.PLD has been proved as a powerful deposition method for oxide materials thin film.The capability to grow thin film with target stoichiometry and the ease of controlling and adjusting the deposition parameter make it as a convenient tool in growing perovskite oxide thin film.To provide the nucleation site and activate the surface diffusion for oxide thin film deposition.Rectification and resistive switching behaviors in the n-n+STO/Si heterojunction were observed by a conductive atomic force microscopy,and the n-n+STO/Si heterojunction exhibits excellent endurance and retention characteristics.The possible mechanism was proposed based on the band structure of the n-n+STO/Si heterojunction,and the observed electrical behaviors could be attributed to the modulation effect of the electric field reversal on the width of accumulation and the depletion region,as well as the height of potential of the n-n+junction formed at the STO/SiO₂/Si interface.Moreover,oxygen vacancies are also indicated to play a crucial role in causing insulator to semiconductor transition.These results open the way to potential application in future microelectronic devices based on perovskite oxide layers on conventional semiconductors.