Ionic conduction and unipolar resistance switching in δ-phase Bi2O3 thin films. (August 2018)

• Record Type: Journal Article
• Authors: Jiang, Jun; Lim, Daw Gen; Ramadoss, Koushik; Ramanathan, Shriram
• Is Part Of: Solid-state electronics. Volume 146(2018)
• Page Start: 13
• Page End: 20
• Publication Date: 2018-08
• Subjects: Semiconductors -- Periodicals; Semiconducteurs -- Périodiques; 621.38152
• DOI: 10.1016/j.sse.2018.04.009
• Languages: English
• ISSNs: 0038-1101

Abstract

Highlights: Switchable materials for memory is an active area of research in electronics. We present a comprehensive study on the physical and device-level properties of delta-Bi2 O3, an archetypal oxide-ion conductor that is also structurally metastable. We show in this work that it is possible to realize both electronic- and ionic- dominated conduction in the low resistance phase by electric-field driven state switching from a nominally ionic conducting high resistance state. We demonstrate this by combination of low temperature magnetotransport as well as impedance spectroscopy. The results presented in this study contributes original physical insights into use of oxide fast-ion conductors in emerging memory technologies. 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 Bi 2 O 3 thin film was stabilized to room temperature via reactive magnetron sputter deposition and characterized by X-ray diffraction and Raman spectroscopy. The δ -phase Bi 2 O 3 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 Bi 2 O 3 thin films show an ionic conductivity of 0.001 S/cm at 400 °C and an activation energy of 0.98 eV. δ -phase Bi 2 O 3 thin films based resistance switching cells (Ag/ δ - Bi 2 O 3 /Pt or Ag/ δ - Bi 2 O 3 /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 10 3 . The resistance switching parameters, like FORMING voltage, SET voltage and RESET voltage can be controlled by the thickness of δ - Bi 2 O 3 . 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.