Bipolar Resistive Switching Characteristics of Thermally Evaporated V 2 O 5 Thin Films

Forming free bipolar resistive switching has been reported in ITO/V2O5/ITO structures. The sandwiched V2O5 film was synthesized by the sol-gel process, and it suffers from the issues of non-uniformity, low thermal stability, and short lifetime due to the presence of intercalated water molecules. In this work, thermal evaporation was employed for the deposition of amorphous V2O5 in ITO/V2O5/ITO structures. Bipolar resistive switching characteristics were preserved and insensitive to annealing temperature below 300 degrees C. Switching disappears when the annealing temperature exceeds 350 degrees C due to the re-crystallization of the amorphous film. Ab initio molecular dynamics method was utilized to simulate the melt-quench process and generate the amorphous V2O5 structure. Significantly, lowered formation energies were found at some oxygen vacancy sites in amorphous structure. The simulation was in agreement with the proposed switching mechanism that the generation of mobile oxygen ions in V2O5 film was essential for the occurrence of resistive switching. The lifetime and the compatibility with IC fabrication of the devices have also been greatly improved.