CeRAM

For more than 12 years, the industry has been looking to Transition Metal Oxide (TMOs) to make resistive memories (RRAMs). In doing so, they used materials like NiO in which "filaments" are grown at higher "electroforming" voltages and currents.  The memory action is created by the connection and disconnection of these filaments between electrodes.  We call this the "filament paradigm," a paradigm that has captured the energies of industry and academia seeking to go beyond FLASH.

CeRAM, stands for "Correlated Electron RAM".   It is a resistive memory that uses TMOs WITHOUT filaments and electroforming.  TMOs have incomplete 3d or 4d atomic shells which go through a Metal-Insulator (phase) Transition (MIT).  These are quantum phase transitions that do not involve anything but a change of valence induced by field or voltage.  In the case of NiO, it is 0.6 V to write an insulating state and 1.2 Volts to write a conductive state - Without any Thermodynamic-like phase transition.  Once the state is written, it is a robust 400 C storage. The speed can be as high as 10s of femto seconds and the read voltage is 0.1-0.2 Volts.

Symetrix has the fundamental breakthrough and IP relating to making TMOs and other oxides work as they should - as "Mott Insulators."   TMOs at ultrathin thicknesses are designed to exploit their "Mottness" by controlling the oxygen "ligand" with the incorporation of another ligand that "cures" the lattice.  The cured lattice creates the MIT conditions for a robust bi-stable switch and memory device.  Clearly, the science to optimize the MIT conditions for CeRAM is different from growing the perfect filament.   We have included several documents on this page that describe and contrasts the science of CeRAM and provide empirical device results.