Ionic conduction and unipolar resistance switching in δ -phase Bi2O3 thin films
Abstract
Fast-ion conductors are of broad interest in diverse fields such as electrochemical energy and non-volatile memory technologies. In this study, δ -phase Bi2O3 thin film was stabilized to room temperature via reactive magnetron sputter deposition and characterized by X-ray diffraction and Raman spectroscopy. The δ -phase Bi2O3 thin films were highly textured along (1 1 1) direction on various substrates and stable during annealing up to 400 °C in air and 200 °C in 5% H2 atmosphere. Electrochemical impedance measurements on δ -phase Bi2O3 thin films show an ionic conductivity of 0.001 S/cm at 400 °C and an activation energy of 0.98 eV. δ -phase Bi2O3 thin films based resistance switching cells (Ag/ δ -Bi2O3 /Pt or Ag/ δ -Bi2O3 /Au) show unipolar resistance switching phenomena. The voltage difference between the RESET and SET voltage is over 0.8 V and the resistance contrast between high resistance state (HRS) and low resistance state (LRS) is greater than 103 . The resistance switching parameters, like FORMING voltage, SET voltage and RESET voltage can be controlled by the thickness of δ -Bi2O3 . In the low resistance state, both the absence of superconductivity down to 2 K and magnetoresistance value indicates metallicity originates from non-stoichiometric bismuth oxide and not pure bismuth metal. The electric field required for SET and RESET operations are estimated to be 7 MV/m and 3.25 MV/m respectively.
- Publication:
-
Solid State Electronics
- Pub Date:
- August 2018
- DOI:
- 10.1016/j.sse.2018.04.009
- Bibcode:
- 2018SSEle.146...13J