Quantum Conductance in Silicon Oxide Resistive Memory Devices
Abstract
Resistive switching offers a promising route to universal electronic memory, potentially replacing current technologies that are approaching their fundamental limits. In many cases switching originates from the reversible formation and dissolution of nanometre-scale conductive filaments, which constrain the motion of electrons, leading to the quantisation of device conductance into multiples of the fundamental unit of conductance, G 0. Such quantum effects appear when the constriction diameter approaches the Fermi wavelength of the electron in the medium – typically several nanometres. Here we find that the conductance of silicon-rich silica (SiO x) resistive switches is quantised in half-integer multiples of G 0. In contrast to other resistive switching systems this quantisation is intrinsic to SiO x , and is not due to drift of metallic ions. Half-integer quantisation is explained in terms of the filament structure and formation mechanism, which allows us to distinguish between systems that exhibit integer and half-integer quantisation. D evices in which the electrical resistance can stably and repeatedly be switched between vastly different values hold great potential as future non-volatile memory elements. So-called Resistive Random Access Memories (RRAMs) exploiting such switching behaviour are actively being developed as alternatives to current technologies such as Flash, which are approaching their limits of scalability and power dissipation 1. We recently demonstrated switching in silicon oxide 2,3
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