Bipolar tri-state resistive switching characteristics in Ti/CeO _x /Pt memory device

Abstract

Highly repeatable multilevel bipolar resistive switching in Ti/CeO x /Pt nonvolatile memory device has been demonstrated. X-ray diffraction studies of CeO 2 films reveal the formation of weak polycrystalline structure. The observed good memory performance, including stable cycling endurance and long data retention times (> 10 4 s) with an acceptable resistance ratio (∼10 2 ), enables the device for its applications in future non-volatile resistive random access memories (RRAMs). Based on the unique distribution characteristics of oxygen vacancies in CeO x films, the possible mechanism of multilevel resistive switching in CeO x RRAM devices has been discussed. The conduction mechanism in low resistance state is found to be Ohmic due to conductive filamentary paths, while that in the high resistance state was identified as Ohmic for low applied voltages and a space-charge-limited conduction dominated by Schottky emission at high applied voltages.

Coexistence of bipolar and unipolar resistive switching in Al-doped ceria thin films for non-volatile memory applications

“…Resistive switching behavior in both modes was activated only after the device was electroformed at forming voltage of 5.5 V with a current compliance of 10 mA. Forming voltage in the Al-doped CeO 2 based devices was found to be smaller than those observed in our earlier CeO 2 based devices without Al-insertion [11]. Therefore, it can be said that Aldoping helps in decreasing the forming voltages and to reduce the electrical power requirements for preparing the device to exhibit reversible resistive switching.…”

Coexistence of unipolar and bipolar modes in Ag/ZnO/Pt resistive switching memory with oxygen-vacancy and metal-Ag filaments

“…The I-V curve shows an Ohmic conduction in low-voltage region, but shows a superlinear increase with a slope of ∼ 2 in highvoltage region, following Child's law, which is an indication of a trap-controlled space charge limited conduction. [14,16,29] Furthermore, to investigate the RS mechanisms of URS and BRS, the temperature dependences of LRS resistance are investigated in these two modes. As shown in Figs.…”

“…Resistive random access memory (RRAM) has received much attention as a promising candidate for next-generation high-speed, high-density nonvolatile storage technology. The resistive switching (RS) characteristics have been discovered in a variety of inorganic [1][2][3][4][5][6] and organic [7][8][9][10] media, especially in many transition metal oxides such as HfO 2 , [11][12][13] ZrO 2 , [14] WO x , [15] CeO 2 , [16] and ZnO. [17][18][19] The RS mode generally can be classified into unipolar RS (URS) and bipolar RS (BRS) based on whether the switching process depends on voltage polarity.…”

Improvement of the Parameter Distribution of TiN/HfO2/CeOx/TiN Memristors by Rapid Thermal Annealing

“…Ceria has been studied as a switching material for memristors [1,2,[16][17][18]. Its excellent oxygen storage/release capacity is because the two most common cation valence states, Ce 4+ and Ce 3+ , are prone to redox reactions [19][20][21].…”