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A controllable and reversible transition of volatile and non-volatile resistive switching is presented in Ag/indium-gallium-zinc oxide (IGZO)/manganese oxide (MnO)/Pt bilayer resistive memory devices. The coexistence of volatile and non-volatile switching characteristics was demonstrated by controlling the current compliance during the SET process. With lower current compliance (

The measurement of specific heat at low temperature for isotopically modified boron single crystals was performed between 0.5 and 100 K using a calorimetric technique known as the time-constant or relaxation method. The results indicate that the specific heat has obvious divergencies at 1.3 K

A pn junction consisting of n-type ZnO nanowires (NWs) on p-type Si substrate exhibits analog resistive switching dependent on the polarity of applied voltage before forming operation for the bipolar switching. The current-voltage curves of Ti/ZnO-NWs/ZnO-seed-layer/p+-Si substrate show diode characteristics with hysteresis in the reverse bias condition, presenting a gradually increasing and then saturated current with repeated voltage sweeps. The current is then further increased with sweeping –V and decreased during the subsequent +V sweep. This polarity-dependent analog switching remains the same during pulse measurement. The analog switching is thought to originate from gradual redistribution of oxygen vacancies, trapping and detrapping of charges in the ZnO NWs, which modulate the depletion width and space charge density. Consequently, the resistance of the pn junction is changed in an analog fashion. After the forming operation, bipolar switching is observed with a transition from high to low resistance states (SET) at +V and reverse transition (RESET) at –V, originating from the formation and rupture of filaments. These results demonstrate multiple features of the ZnO NWs based pn junction, including diode characteristics, analog-type resistive switching before forming operation, and digital-type bipolar switching after forming.

The bias-polarity dependent multimode threshold and bipolar resistive switching characteristics in bi-layered Pt-Fe2O3 core-shell and γ-Fe2O3 nanoparticles assembly were investigated. The Ti/Pt-Fe2O3-core-shell-nanoparticles (∼20 nm)/γ-Fe2O3-nanoparticles (∼40 nm)/Pt structure exhibited a threshold switching upon applying −V at Ti electrode. However, the filaments were formed at +V and subsequently ruptured at −V, featured to be bipolar switching. After rupturing filaments, it returned to threshold switching mode. The presence of core-shell nanoparticles facilitates the threshold switching either by temporary formation of filaments or enhanced charge transport. Also, the oxygen reservoir role of Ti electrode was essential to form stable filaments for bipolar switching.