Mechanism of GeO₂ resistive switching based on the multi-phonon assisted tunneling between traps

Abstract

Model of evenly distributed traps in bulk dielectric is proposed for the resistive memory switching mechanism. Switching from high resistance to the low resistance state is explained by several-fold increase in trap concentration after the application of switching voltage. Both high and low resistance conductivities are governed by multi-phonon ionization and tunneling between neighboring traps. Thermal trap energy for oxygen vacancy and electron effective mass for crystal a-GeO 2 were calculated using density functional theory and used for the fitting of our charge transport model of resistive memory. The model was verified on the TaN-GeO 2-Ni structure with good semi-quantitative agreement with experiment. V

$\hbox{Ni/GeO}_{x}\hbox{/TiO}_{y}\hbox{/TaN}$ RRAM on Flexible Substrate With Excellent Resistance Distribution

“…The set and reset current densities (J reset and J set ) at 0.5-V read are 3 × 10 −3 and 9 × 10 −5 A/cm 2 for 11 300-μm 2 RRAM, which are close to the 4 × 10 −3 and 9 × 10 −5 A/cm 2 values for the 101 700-μm 2 device. This result suggests the bulk conduction effect that is well predicted by modeling [19]. We also studied the RRAM with different top electrodes.…”

“…Low set and reset power, large enough 85 • C retention window, and good electrical endurance are also reached. These much better performances are attributed to the bulk transport property of hopping conduction [19]- [22] and the less destructive low power switching in Ni/GeO x /TiO y /TaN RRAM.…”

“…The ultralow reset power of 3 μW (−1 μA at −3 V) is related to the break of the weakly linked phonon-assisted tunneling pass by injected electrons over electrode [6], [7], [19]. The low switching current is due resistance on the order of megaohms by hopping conduction [20] via phonon-assisted tunneling between traps [19]. A good HRS/LRS memory window of 30 is measured at 0.5-V read, with small changes between the 1st and 100th dc-cycled I-V curves.…”

Evolution of the conductivity type in germania by varying the stoichiometry

“…1 Germania films also show resistive switching effect, which is promising for the next generation of high performance non-volatile flash memory. 2,3 The energy diagram of the Ge/GeO 2 structure was calculated in Ref. 4, using quantum chemical simulation.…”

“…The same GeO x films are used in ReRAM devices. 2 The second "PDA5" and the third "PDA20" groups of samples were treated by applying PDA in an O 2 atmosphere at 300 C for 5 min and 20 min, respectively. The 300 C annealing is a very low temperature process for SiO 2 sublayer growing.…”