Formation of Remote Quantum Point Contact Inside Dielectric Medium of an AlOx/SiOx ReRAM

Remote quantum point contact (QPC) far from the metal electrodes was observed in forming free aluminum oxide (AlOx)/silicon oxide (SiOx) resistive random access memory (ReRAM) cell, which was resolved at low bias. QPC behavior of the cell was attributed to confined oxygen vacancies across uncorrelated narrow grain boundaries of intermediate O3 treated thin AlOx layer of the stack, which was designed to restrict vacancy channeling between the two immediate reservoirs; i.e., from beneath SiOx to the top as-deposited AlOx layer. From time dependent dielectric breakdown (TDDB) characteristics of the cell while assessed under low stress biases, we found one to one correspondence between TDDB and its bias dependent QPC. Furthermore, we found that, under steady state and especially at low biases progressive breakdown (PBD) of the dielectric exhibited two-level random telegraph noise (RTN) like conductance fluctuations, which occurred in the magnitude of ${G}_{{0}}$ or in its multiples depending on applied bias to the cell, that demonstrated a correlation between electron trapping and maximum QPC instability during filament growth. Low voltage QPC-based switching under dc bias sweep, its correlation with TDDB and RTN under the steady state thus provided us a framework to analyze the evolution of QPC well before reaching the SET state in an AlOx/SiOx cell, which is different from the usual QPC evolution as found near contact regions in a conventional SiOx cell without accompanying engineered AlOx barrier.