Study On The Transparent Resistive Switching And Self-rectifying Properties Of The In-Ga-Zn-O Thin Film

Resistive switching random access memory(RRAM) has recently attracted extensive investigation due to its simple structure, low power consumption, high speed, etc. Especially,the transparent RRAM(TRRAM) has attracted much attention owing to its advantages of high transparency. The self-rectifying with RRAM can not only realized high-density, but also effectively alleviated the cross-talk effect. The In-Ga-Zn-O films, carrying the advantages of high mobility, low process temperature and high transparency, have attracted more attention from the public. In this study, we have fabricated the bipolar TRRAM withα-IGZO/STO/α-IGZO, highly transparent RRAM with α-IGZO/Ga2O3/α-IGZO, and the self-rectifying effect with Ag/In-Ga-Zn-O/Pt RRAM. The resistive switching properties and mechanisms of these devices have been analyzed. The main achievements are summarized as follow:We investigated the α-IGZO/STO/α-IGZO bipolar TRRAM based in quartz glass substrate have been fabricated by magnetron sputtering technique and pulsed laser deposition technique(PLD). The transmittance, current-voltage(I-V) characteristics curve,retention property, endurance property and conduction mechanism of the device were also discussed. The results of X-ray diffraction spectra(XRD) showed that the films are amorphous. The results of UV-VIS showed the TRRAM device with average transmittance of 75% in the visible region. The ratio of high resistance state(HRS) to low resistance state(LRS) was 6, and it can be kept 250 cycles. Meanwhile, the currents of HRS and LRS had no obvious fluctuations after 5×104s. The conduction mechanisms at HRS and LRS were attributed to the SCLC. The fact was due to trapping and releasing of electrons affected the conductive electron, thus changed the current of the device.The TRRAM based on α-IGZO/Ga2O3/α-IGZO structure was deposited by magnetron sputtering technique, and gallium oxide(Ga2O3) as dielectric layer had a great potential to transparent because of its wide bandgap. The device possessed high average transmittance of 91.7%(maxmum:98.3%, minmum: 81.3%) in the visible region, and the band gap of Ga2O3 was 5.1e V. Different polarity of electroforming voltage would impact the distribution of the oxygen vacancies and result into the different direction of switching. The result of conduction mechanism and temperature dependence was hopping conduction. The trapspacing of HRS and LRS were found to be 1.4nm and 0.7nm, the activation energy of HRS and LRS were 0.23 e V and 0.15 e V.The Ag/In-Ga-Zn-O/Pt structure RRAM devices was fabricated based in In-Ga-Zn-O films as dielectric layer. It can be found that the self-rectifying performance of the divices exist at LRS. The self-rectifying characteristics remained stable at tested temperature from303 K to 393 K. The devices with Cu, Ti and Ag as the top electrodes, respectively, and a more remarkable self-rectifying effect of the devices due to the higher metal work functions.The area size of the top electrodes impacted the resistance of the RRAM. The devices at HRS and LRS were fitted by the SCLC and Schottky at different temperatures, respectively.The Schottky barrier height was determined to be 0.32 e V, and the dynamic dielectric constant εr was extracted to be 7.9. We found that the Schottky barrier at the top electrode and In-Ga-Zn-O film interface was responsible for the self-rectifying characteristics.